Ecology and Evolution Flashcards

Question

What does the Energy Attenuation Hypothesis predict?

Answer 1

Communities with more efficient energy transfer should have longer food chains. Communities with higher primary productivity ought to have longer food chains.

Answer 2

Ectothermic food chains tend to be longer than endothermic food chains as less energy is expended regulating their temperature.

Answer 3

At low productivity, adding more energy equates to more trophic levels, but there's a limit. Only 3-4 trophic levels are found, typically.

Answer 4

MacArthur and Elton

Answer 5

Pimms and Lawton

Answer 6

Longer food chains are less stable. Chance variations in population size are amplified up the food chain leading to unpredictable dynamics for the top predator.

Answer 7

Environmental variability is correlated with food chain length. In more predictable environments, food chains will be longer.

Answer 8

Jennifer Dunne. Removing species with few connections tends to have little effect. There are critical thresholds whereby after a certain number of individuals of a species have been removed, there are marked effects on the food web. Robustness increases with connectance.

Answer 9

Secondary extinctions that followed simulated extinctions.

Answer 10

May, Lawton and Pimm extended the Lotka-volterra models to sets of interacting species.

Answer 11

Create artificial food webs. Manipulate the properties, and examine the stability. E.g., food webs with different numbers of trophic levels, but similar values for S and C.

Answer 12

Food chains would be short, and network complexity reduces stability. Both greater S and C decreased stability.

Answer 13

If β(SC)^1/2 < 1.

Answer 14

Randomly assembled food webs with different numbers of species, connectances and interaction strengths (β).

Answer 15

Interaction strength: the impact of the changing the abundance of a species on another species.

Answer 16

The food webs observable in nature are not a random subset of all food webs. They are the stable ones. May's model could be attributed to survivorship bias.

Answer 17

Labourious, but informative. Manipulations can be used to identify keystone species and indirect effects.

Answer 18

Excluding the starfish Pisaster from rocky shores reduced species diversity and shifted food web structure. Ethically challenging to manipulate real ecosystems.

Answer 19

Lab experiments with aquatic micro-ecosystems. Corroborated Bob May. Fine control over the composition and conditions of these micro-ecosystems. With 2 species, 2.5% of populations went extinct. With 8 species, 27.5% of populations went extinct.

Answer 20

Species are connected, but a change in the abundance of one species doesn't propagate to the other species. More important than complexity. A highly stabilising factor.

Answer 21

Populations of two different species are dynamically linked, but not through a feeding interaction.

Answer 22

the hare and the rabbit aren't directly competing, but they share a predator. If the abundance of the hare increases, the abundance of eagles increases, so predation on the rabbit increases.

Answer 23

Cats reduce the mice population, which increases the bee population. The plant population then increases also due to a mutualistic relationship with the bee pollinators.

Answer 24

Grey squirrels appeared to outcompete red squirrels, but actually they share a common pathogen (the squirrelpox virus) to which grey squirrels are more resistant. When they interact, red squirrels are less resistant, so suffer more from the virus.

Answer 25

A keystone species in the otter-urchin-kelp cascade.

Answer 26

A species whose impacts on the community or ecosystem are much larger than expected based on its abundance or biomass. Often predators, but not always. Key to conservation.

Answer 27

A keystone species that went extinct in the Yellowstone National Park, but were restored in the late 20th century.

Answer 28

Their prey (ungulates and elks) decreased, so herbivory and browsing also decreased. Aspen, cotton wood and willow increased in abundance, so beavers also increased.

Answer 29

Keystone species/ecosystem engineers whose dams provide a habitat.

Answer 30

Keystone species as all frugivores in rainforests depend on them. Fig trees, in turn, depend on specialised pollinators (fig wasps), thus fog wasps are arguable also keystone species.

Answer 31

Keystone herbivores (not a trophic cascade, however, as there are only 2 levels). By grazing, the tortoises reduce vegetation from trees to short grass on Aldabra island.

Answer 32

Create large openings in the vegetation that affect plant regeneration in neotropical rainforests.

Answer 33

Not all ecosystems have a keystone, and keystones can be more easily identified after extinction. As species are removed, the stability of the ecosystem decreases. Different species within the ecosystem can be differentially important.

Answer 34

Feeding Links

Answer 35

Feeding interactions in which one species benefits and the other doesn't.

Answer 36

Interactions where one species benefits from the other.

Answer 37

One species gains nutrition from another.

Answer 38

Parasites, predators, parasitoids and herbivores.

Answer 39

Nt+1 = Nt + Births - Deaths

Answer 40

When births = deaths.

Answer 41

Resources and competition for them (inter- & intra-specific) and natural enemies.

Answer 42

The host is always harmed by the parasite living in or on it, only part of the host is consumed, the parsite tends to be much smaller than the host and only 1 of very few hosts are consumed per parasite.

Answer 43

The host is always killed by the parasitoid which lives in or on it. The parasitoid kills one host in its lifetime. The parasitoid and the host are similar sizes.

Answer 44

A parasitoid wasp lays its eggs in aphids that then hatch and eat the aphid. Another parasitoid wasp larvae eats ladybirds then tunnels itself out to form a coccoon.

Answer 45

The resource individual is a producer. The herbivore consumes only part of each resource individual.

Answer 46

Lay their eggs in a seed. The larvae then eat the seed.

Answer 47

An ecosystem engineer that provides habitats for many marine organisms. A primary producer.

Answer 48

When the lionfish was introduced into the Caribbean sea, they were invasive and non-native, so reduced the populations and carrying capacities of native fish.

Answer 49

Over-hunting of sea otters in the Pacific increased the populations of urchins and decreased the populations of kelp as well as kelp-dependent marine organisms.

Answer 50

The Opuntia prickly pear was well adapted to arid conditions, so became overgrown and invasive in Australia. Cactoblastis cactorum moth was found in Mexico (the native habitat of Opuntia) to act as a biological control agent and reduce the carrying capacity of the Opuntia population.

Answer 51

Solve for dN/dt= 0 using the Lotka-Volterra equations.

Answer 52

Combinations of predator and prey that lead to an unchanging prey population. r/a.

Answer 53

Combinations of predator and prey that lead to an unchanging predator population. q/fa.

Answer 54

In more complex food webs, there are many predators for each prey and vice versa that act as a buffer.

Answer 55

The Arctic environment has a simple food web with the hare having few other predators and the lynx having few other prey.

Answer 56

The intake rate of a conusmer as a function of food density.

Answer 57

Type I functional response. Assumes there is a cobstant, linear relationship between the prey density and the number of prey consumed. The model can be adjusted to be more realistic by adding in functional response graphs.

Answer 58

Parasites, herbivores and pathogens can too.

Answer 59

Cliff swallows nest colonially. The number of parasites (usually ectoparasites) increases with the size of the colony.

Answer 60

Pest pressure from specialised herbivores or pathogens causes density-dependent survival of seeds and seedlings, promoting diversity via a negative feedback system. A relatively rare species can be released from the affects of natural enemies, and then increase in abundance.

Answer 61

More vulnerable to extinction.

Answer 62

Created by damming a river. This flooded a rainforest, creating islands. Such habitat fragmentation can affect trophic cascades.

Answer 63

Lack of predators of vertebrates as these predators are most vulnerable to extinction. Densities of rodents, howler monkeys, iguanas and leaf-cutting ants were 10-100x higher than on nearby mainland. Densities of seedlings and saplings reduced dramatically. Severe trophic cascade due to the lack of top-down regulation by predators.

Answer 64

Concerned with the distribution and abundance of organisms.

Answer 65

Bacterial growth curves. Wildebeest recovering from Rinderpest.

Answer 66

All groups of birds have declined from 1970-2016. Farmland birds have declined the most by 90%. From 2018-2023, they declined again by 90%.

Answer 67

Populations should be able to recover from low-density. Eventually, environmental limitations will halt population increase. Populations also flutuate apparently randomly.

Answer 68

Bacteria divide continuously, all are out of sync with each other= continuous time. Wildebeest have a single reproductive event each year, all calve within a week of each other; synchronised reproductiv events= discrete time. One is more useful for a given population.

Answer 69

A trait that influences demography (population dynamics).

Answer 70

Maximum per capita population growth rate. A life-history trait.

Answer 71

The typical number of offspring per clutch or brood, number of clutches/broods per year, mortality rate through reproductive life, age at first reproduction and reproductive lifespan.

Answer 72

The maximum number of individuals an environment can support-- carrying capacity. A property of the environment, not a life-history trait.

Answer 73

When N=K, where n is population size.

Answer 74

When r takes the same positive value regardless of population size, it's exponential growth. Logistic growth occurs when r decreases as the population increases towards the carrying capacity.

Answer 75

…this is an oversimplification. This affected fishing quotas as as it was assumed that fish stocks were at K, but really they were much lower, so fishing to K/2 almost drove certain fish to extinction.

Answer 76

The change in population size in a single growth step.

Answer 77

Environemntal stochasticity. The availability of acorns fluctuates due to the weather.

Answer 78

The tawny owls have a smaller value of r than mice.

Answer 79

You will mostly observe fluctuations in K, once equilibrium/carrying capacity is reached.

Answer 80

By varying K by pulling random numbers from a normal distribution.

Answer 81

There is a still a mean K, but K fluctuates. If one year is good, this indicates nothing about the next year.

Answer 82

… the less responsive the population is to changes in the environment.

Answer 83

The population is more responsive to changes in K.

Answer 84

Choose the simpler model when confronted by a simpler and a more complex model. However, simple models/toy models may be able to reproduce simple patterns, but are not entirely trustworthy.

Answer 85

Larger values of r mean the population recovers faster. Smaller values of r mean the population recovers more slowly, and it's seldom at its carrying capacity.

Answer 86

Humpbacks are still hit by ships. Humpback whales produce 1 calf every 2-3 years. It takes 5-10 years for a calf to reach sexual maturity. It has a low value of r.

Answer 87

The r/K continuum is difficult to estimate in real populations and only goes so far. r can evolve.

Answer 88

At K, there is lots of competition as resources are scarce. If the population is often at K, there's selection to produce few, larger offspring. Competition favours large body size, late maturation and having few, large offspring. E.g., humpback whales.

Answer 89

r selected species are selected to have higher values of r as they live in more hazardous environments. They can recover easily from low density. Large litters, early sexual maturity, frequent broods, small body size and small offspring. E.g., rabbits.

Answer 90

Mean value of K.

Answer 91

This is due to harsh winters. If the water is frozen, herons can't reach any fish. This can be modelled as a discrete-time logistic with hazards that kill members of the population randomly.

Answer 92

1/r, hence species with higher r values recovery faster.

Answer 93

Litter size: 1-14. Can produce one litter per month at low density. 13 rabbits were introduced to Australia in 1859. In 1866, hunters shot 14,000 rabbits. In 1940, there were an estimated 60 million rabbits across Australia.

Answer 94

E.g., a hazardous environment might mean selection on r, leading to earlier maturation and smaller body size. This makes individuals more susceptible to hazards, which increases selection on r.

Answer 95

Always adds or subtracts the same number of individuals, but this isn't realistic. No stochasticity is factored in.

Answer 96

r is a real number, so in the model, fractional individuals are possible, which isn't the case in real life.

Answer 97

Truncate, or make the actual number of new individuals a random variable and use the Poisson distribution.

Answer 98

Randomness inherent to populations as a result of randomness in the birth and death processes. Only potent in small populations.

Answer 99

mean. Variance cannot be changed.

Answer 100

Due to environmental or demographic stochasticisty. You cannot tell which. For a small population, fluctuations due to stochasticity at equilibrium are greater.

Answer 101

The actual number that die or are born isn't constant. It includes a component of randomness.

Answer 102

The species can go extinct just by chance. For demographic stochasticity to cause extinction, K<50 roughly: the population size must be very small.

Answer 103

This puts a huge selection on r.

Answer 104

Once baundant in U.S. prairies, the population plummeted when the bubonic plague was introduced. In one population, only males were born in one year. This led to extinction due to stochasticity in the sex ratio.

Answer 105

… by genetic drift, especially if the population remains small for a long time.

Answer 106

Had undergone genetic erosion due to drift in tehir small population, so the subspecies couldn't be saved. Instead, panthers from Texas were introduced in 1955.

Answer 107

Weren't able to expand their range and were restricted to south Wales, until Swedish red kites were introduced.

Answer 108

The population growth rate decreases as populations get smaller.

Answer 109

Population growth rate becomes negative below a critical threshold in population size.

Answer 110

If the herd is too small, all the offspring are eaten as they can't defend themselves against wolves. They would suffer an Allee effect.

Answer 111

They hunt in packs, and their population shrank due to canine distemper and rabies.

Answer 112

There could be an Allee effect as a female is attracted to several males' calls.

Answer 113

4kg-- the heaviest parrot. Flightless and nocturnal with whiskers to feel its way in the dark. Breed slower than any other bird (every 2-7 years, when high-quality food is available). Can sometimes live for more than 100 years!. Low basal metabolic rate allows it to subsist on low-quality food. once hugely abundant, but cannot recover easily.

Answer 114

Any native mammals.

Answer 115

When the Maori arrived ~1200 years ago, they brought dogs, intrdouced Pacific rats and hunted kakapos. Europeans in the late 18th century brought more mammals-- mustelids that predate ground-nesting birds.

Answer 116

Stoats, ferrets and weasels.

Answer 117

This island had no mustelids, but did have cats and ongoing predation.

Answer 118

51 birds. There are more males than females.

Answer 119

An intensive kakpo recovery programme began.

Answer 120

Every kakapo bird is fitted with a smart transmitter and tracked.

Answer 121

Kakapo birds are caught annually and inspected.

Answer 122

Some kakpo nests are monitored remotely; others have a dedicated human.

Answer 123

Strict biosecurity protocols and traps.

Answer 124

Feeding stations are re-filled throughout the island.

Answer 125

69 have been incubated and hand-reared so far, including removing chicks when the food supply fails. This eliminated some of the demographic stochasticity.

Answer 126

21 cases. Twelve recovered after treatment. Two adult females and seven chicks/juveniles died. Birds were helicoptered to the mainland for intensive treatment. Associated with low immunity, likely due to genetic erosion.

Answer 127

4000 individuals.

Answer 128

Due to potential Allee effects.

Answer 129

Low r = smooth curve to equilibrium. Higher values of r= dampened oscillations followed by limit cycles. Very high values of r= chaos-- entirely unpredictable.

Answer 130

Population size just fluctuates below and above K by the same amount repeatedly in a stochasticity-free discrete-time logistic.

Answer 131

Not stochastic, but highly susceptible to initial conditions.

Answer 132

St. Kilda's wild soay sheep appeared chaotic due to tehir large fluctuations. In reality, many sheep give birth to twins at the same time. They have a high r value, so can recover post-winter.

Answer 133

High r values. In a single generation, the population can add a large number of recruits.

Answer 134

Associated with exceeding K. For high values of Nt, the population size of the next generation will actually be lower than the current population size.

Answer 135

this means once the population booms, it can crash back down again. The addition of a 1:1 line on a Nt against Nt+1 graph illustrates this clearly.

Answer 136

When Nt= K, but with chaotic dynamics, this will never be reached.

Answer 137

Intervention should be earlier, before the population has reached its minimum viable population size.

Answer 138

Taking pre-gathered data on one species to compare with another species.

Answer 139

Single male, multiple females.

Answer 140

Single female, multiple males.

Answer 141

Sexual selection. Why do male peacoacks have such tails?

Answer 142

Tend to have paired systems where both parents care for the offspring. In polygamous mtaing systems, the males leave, so females have to raise the offspring.

Answer 143

Red-headed weaver: monogamous with dispersed territories. Southern masked weaver: polygynous, and nests in colonies. Village weaver: polygamous and nests in colonies.

Answer 144

Correlation between monogamy and insect-eating, polygamy and seed-eating. Pairs can catch insects to feed their offspring, but it's easier to find lots of seeds to support a large colony.

Answer 145

Polygamous groups tend to be colonial. Monogamous birds tend to be solitary. Polygamy increases genetic diversity and variation.

Answer 146

Don't represent independent data points.

Answer 147

Comparative studies can't prove something is the result of something else-- correlation not causation. Crook didn't quantify his ecological variables. Closely-related species don't represent independent data points. Causalty could be in the other direction with sociality determining what birds eat.

Answer 148

Indri, macaque, baboons and mandrils.

Answer 149

Largest out of 80 different types of lemur. Males and females tend to be the same size.

Answer 150

Females are just slightly smaller than males.

Answer 151

Males are roughly double the size of females.

Answer 152

Quantified ecological variables: sexual dimorphism= difference in weights, plotted against sex ratio in the breeding groups.

Answer 153

When there's high sexual selection and competition between males, males may be larger to compete with one another. The higher the sexual dimorphism, the higher the number of females per male.

Answer 154

There may be more untested hypotheses. Are species independent? This hasn't been tested. Pan and gorillas are more closely related than indri and lemurs, so some data points rae more independent than others.

Answer 155

Statistical analyses assume data points are independent. Closely-related species tend to be similar because they share traits through common descent, rather than independent evolution.

Answer 156

Doing an experiment, but thinking you sample size is larger than it is.

Answer 157

Partitions out the effects of the shared relationship/the phylogeny. Finds the differences between datapoints. Accounts for the statistical non-independnece of the data.

Answer 158

The pollen-laden female wasp lays her eggs inside the fig. Pollinates the flowers on teh fig tree. Male wasps fertilise the females. Some females lose their wings, and spend the rest of tehir lives their. Others don't.

Answer 159

Both sexes are smaller than their non-pollinating counterparts. Some non-pollinators can lay their eggs without even entering the tree.

Answer 160

Non-pollinating males are armoured, often live their whole lives in fig trees and some can be violent.Pollinator males don't tend to be violent. This is just a correlation as they are closely-related species.

Answer 161

The higher the female density, the lower the level of male injury. Blending phylogeny with quantified data by plotting the contrasts between species instead of the species as datapoints themselves.

Answer 162

Solitary. Only a few times in spring does it emerge to find a mate.

Answer 163

They pack together on a cliff to rear their young, but the breeding pairs seldom interact.

Answer 164

They avoid predators in a group. Each individual benefits directly from being in a group. There is no cost.

Answer 165

They all produce a molecule to break down a food source, so they can take it up.

Answer 166

Any behaviour that impacts another organism.

Answer 167

Generally, slime moulds are single cells that break down wood. When the food source dries up, they aggregate together to form a fruiting body that produces spores. Spores disperse to find a new patch of food. Slime moulds are semisocial.

Answer 168

The stalk cells are sterile or may have died in some species. Their reproductive potential is over, but the cells in the fruiting body can still reproduce.

Answer 169

Made up of zooids with an air sac on top. As juveniles, they can live independently, but as adults they can no longer live alone and have specialised roles.

Answer 170

After the termite king and queen make a nuptial flight, they burrow, mate and the queen produces the first batch of eggs. The workers help her produce more eggs. The queen can live for 50-60 years! All the workers are sterile.

Answer 171

Signalling theory, game theory and major evolutionary transitions.

Answer 172

An interruption of evolution as a series of gradual changes. Instead of a continuum, it's a series of steps. Revolutions.

Answer 173

Major transition in how information is passed on.

Answer 174

Evolution of information transfer by DNA. Bits of genome have clustered together to form chromosomes that have come together to form a genome.

Answer 175

Endosymbiosis. All eukaryotes descend from an ancestor with an alpha-proteobacterial symbiont. Two individuals from different domains coming together.

Answer 176

Ancestors would have been asexual. Producing gametes relies on another individual to transfer information to the next generation.

Answer 177

Individual cells form groups then become a multicellular organism. A unicellular alga formed groups with reproductive division of labour. Some algae were soma cells, whilst others reproduced. The transition to multicellularity occurred multiple times.

Answer 178

Extreme form of a social group with total reproductive division of labour between different castes.

Answer 179

Most recent common ancestor of colonial termites.

Answer 180

Type of major evolutionary transition. When individuals come together to form a 'higher-level' individual, so that individuals can no longer reproduce separately, just as this new individual.

Answer 181

Replicating molecules becoming populations of molecules, prokaryotes to eukaryotes, protists to animals, plants and fungi and solitary individuals to colonies.

Answer 182

Independent replicators to chromosomes, RNA to DNA, asexual clones to sexual populations and primate societies to human societies, incl. language.

Answer 183

A cooperative group.

Answer 184

High relatedness is important. Low promiscuity means an individual is 0.5 to its offspring and its siblings. Cooperation can evolve, then be lost again, if promiscuity increases.

Answer 185

No selection or conflict within the group.

Answer 186

Aligning genetic interest by increasing relatedness through monogamy (in sexual organisms) or clonality. Repression of competition.

Answer 187

Workers don't mate, but can produce male eggs. Males arise from unfertilised eggs. Worker policing: workers eat the eggs laid by other workers.

Answer 188

No competition between cells as they are all the same. There's a division of labour: some cells reproduce whilst others don't. If cells with one genotype becom ethe germline and cells with another genotype become the soma, there would be conflict as soma cells do all the work. This is avoided in a clonal system, but where cells ahve different genomes, this is an example of conflict, e.g., chimeric genomes.

Answer 189

They are dependent on each other to reproduce.

Answer 190

r(offspring) = r(siblings). When the queen has mated only once, relatedness to the siblings and offspring is the same. High relatedness in the group.

Answer 191

r(nephews and nieces) < r(offspring). Multiple queens in a colony. Relatedness to potential offspring is greater than the offspring they help to rear, because they'll be your nephews and nieces instead of siblings.

Answer 192

Monogamy was ancestral to all the independent origins of multicellularity. Polygamy has only evolved after eusociality evolved. Major evolutionary transitions are irreversible.

Answer 193

Only evolves from ancestors with clonal group formation (discovered by Bertie Fisher).

Answer 194

Cells aggregate together, but haven't undergone a transition as they can still separate. Can evolve when groups are non-clonal.

Answer 195

Subsocial: where a single cell produces many clones that stay with the parent, r=1. Semisocial: cells aggregate together; they're not clonal.

Answer 196

A subsocial route with a single cell stage. Organisms begin from a single-celled egg-- a single cell bottleneck. This removes competition as all cells are clonal.

Answer 197

Egalitarian, e.g., mitochondria and host cells. Competition is removed as genes are transmitted together.

Answer 198

Fraternal.

Answer 199

In monocultures, the density of altruistic helpers and reproducing bacteria is greater than that of cheats. In a mixed culture, the cell density of cheats increases.

Answer 200

Thus, their evolutionary lineages are not completely matched to their hosts', and a transition will not occur.

Answer 201

Often small, extinction-prone and patchily distributed in space.

Answer 202

… density dependence kicks in, and the population size approaches carrying capacity.

Answer 203

… extinction.

Answer 204

Variation in population size due to variation in births, deaths and sex ratio around the mean. Works alongside environmental stochasticity.

Answer 205

Often have small, extinction-prone populations within them. Anthropoengenic activities can lead to patchy and fragmented landscapes.

Answer 206

Stochastic events can cause local population sizes to fall to zero.

Answer 207

The tendency for population growth rate to become very small or even negative when the population size is very small.

Answer 208

Populations can become trapped in small patches of habitat that tend to lack the resources to support them long-term. These populations are extinction-prone.

Answer 209

E.g., insects in clusters of acacia trees in Kenya, or populations in ponds (like inverse islands).

Answer 210

Demographic and environemntal stochasticity, genetic effects and Allee effects.

Answer 211

They may be re-colonised by immigrants from other populations.

Answer 212

The dispersal ability of a species relative to the level of habitat fragmnetation will determine how its population is structured and whether it can persist in fragmented landscapes.

Answer 213

Population of populations. Species can persist as a balance between extinction and colonisation events.

Answer 214

The number of patches occupied at any one time depends on the balance between rates of colonisation and rates of extinction.

Answer 215

Areas of meadow (suitable habitat for the butterfly) surrounded by sea and forest (unsuitable habitat) in part of Finland. Local extinction will be balanced by butterflies colonising previously uncolonised areas.

Answer 216

First determined by Richard Levins in the 1960s. Rate of change of occupied patches= colonisation (c ) - extinction (e).

Answer 217

…the greater the proportion of patches occupied.

Answer 218

When there's an intermediate number of patches occupied. There are lots of empty patches available to be colonised, as well as lots of occupied patches to generate colonists.

Answer 219

As the patches are saturated.

Answer 220

This gives the average proportion of patches occupied in a given landscape in a given time.

Answer 221

Patches are isolated from each other in a landscape, so it's harder for individuals to disperse to colonise other patches.

Answer 222

When patches are far apart, and when populations are small in the metapopulation. High extinction rate, and low rate of colonisation.

Answer 223

Across different populations in a metapopulation. Increases the chance of landscape-wide extinction.

Answer 224

Across different populations in a metapopulation. Decreases the probability that all local patches will go extinct simultaneously. Dispersal events allow patches where local populations have gone extinct to be re-colonised. However, lots of drivers of environmental stochasticity, e.g., weather, tend to affect populations in that environment similarly.

Answer 225

Minimising extinction rates, and maximising colonisation rates. Conserving empty habitat patches. Reducing population synchrony. Most of this can be achieved through habitat mangament, e.g., ensuring some populations do better in wet years and others do better in dry years, or by ensuring patches are well-connected.

Answer 226

Metapopulations, patchy populations, mainland-island dynamics and source-sink dynamics.

Answer 227

Monitored change in occupancy of holly leaf miners in these patches (holly trees in a woodland over time). Every holly plant has leaf miners on it every year. The populations appears patchy, but the flies that lay the leaf-mining larvae are mobile enough that it is effectively one habitat. best treated as one population.

Answer 228

The mainland, core population is large enough that it effectively never goes extinct. It should be protected. The satellite populations are small, so extinction prone, and are reliant on re-colonisation from the mainalnd population.

Answer 229

The source is a large, high-quality habitat-- a next exporter of individuals. The sink only persists due to immigration from the source, otherwise it would become extinct. Without high immigration, the right hand side of the equation (Nt+1= Nt + births - deaths + immigrants - emigrants) would be negative, and teh population would decline nnntowards extinction.

Answer 230

A group of species that occur together in space and/or time, and compete for limiting resources. Inherently competitive.

Answer 231

Something that is consumed, and used up for growth.

Answer 232

E.g., CO2 cannot be limiting for plants because it's so availble; whereas nitrates in the soil can be depleted, so can be limiting.

Answer 233

Species in the same trophic guild have similar feeding roles in an ecosystem.

Answer 234

In one hectare of the the tropical rainforest in Brazil, there are 400 different species. Other examples include tropical coral reefs.

Answer 235

Low diversity. E.g., Coco de mer is one species that dominates the palm forests in the Seychelles.

Answer 236

Two species cannot exist on one limiting resource, if other ecological factors remain constant.

Answer 237

If there's only one limiting resource and no other meaningful ecological variation, we only expect to observe one species, because it will be better adapted, and outcompete the other species.

Answer 238

Cthamalus is completely excluded from the lower shore by Balanus, but persist in the upper shore because it is more tolerant of desiccation. Balanus was less well-adapted to the upper shore, so were killed there. Cthamalus larvae were still found on the lower shore when dispersed, but as adults they were killed due to increased predation. As Cthamalus is less aggressive, it was outcompeted by Balanus.

Answer 239

The planktonic larvae swims around, then fixes to the rock by secreting CaCO3. The barancales open their paltes to feed-- filter feeders. They clsoe their plates to prevent desiccation.

Answer 240

Has symbiotic alage termed chlorella.

Answer 241

Both P. bursaria and P. aurelia eat bacteria. P. aurelia outcompetes P. bursaria in aerobic conditions, but P. bursaria can persist in anoxic conditions where P. aurelia cannot.

Answer 242

P. aurelia outcompetes P. bursaria.

Answer 243

Both species persist, but P. bursaria is mostly confined to the bottom of the beaker. This is because anoxia occurs at the bottom of the beaker, but P. bursaria can geneerate O2 internally via its photosynthetic symbiont.

Answer 244

The 2 species didn't occur together, even though the distribution of their food (algae) was the same, and they were almost indistinguishable.

Answer 245

There was character dispalcement: H. ulvae fed on larger food particles and became significantly larger than H. ventrosa.

Answer 246

Photosynthetic, planktonic organisms. Diatoms are contained within a unique silica-frustule cell wall. Can be grown in culture such that silica is the limiting factor.

Answer 247

The level to which the concentration of a limiting resource is reduced by an equilibrial monoculture of a species.

Answer 248

When the concentration of silica is high, the population of the diatoms increases. Their growth depletes the silica, hence their population growth rate slows. R* value: concentration of silica at equilibrium.

Answer 249

Different species have different R* values, but each R* value is unique and constant for that species.

Answer 250

Highly mobile.

Answer 251

1. Species compete for a single, limiting resource. 2. The resource is labile, and the mixture is well-mixed.

Answer 252

The minimum resource concentration a species requires for positive population growth. E.g., the diatoms cannot take up silica from the water when silica concentration is below the R* value for that species.

Answer 253

The species with the lowest R* for the limiting resource is predicted to be the best competitor.

Answer 254

Often C4. Compete for limiting nitrogen.

Answer 255

Nitrates are labile. NH3 is not.

Answer 256

Assumptions of the R* theory were met. 4 species. After 5 years, they measured the biomass and R* values of species in monocultures. It wasn't the species ebst able to accrue biomass that were most abundant. It was the species with the lowest R* values.

Answer 257

Agropyron outcompeted Agrostis. R* theory predicts this, but monoculture biomass doesn't.

Answer 258

Two species persist together forever.

Answer 259

Species 1 outcompetes and excludes species 2, or vice versa. Stable coexistence. Sometimes the dominant species cannot be predicted because this depends on the initial conditions: there are two alternative equilibria, e.g., the species that arrives first may dominate.

Answer 260

Competition coefficients by which interspecific competitors are weighted.

Answer 261

… adding an individual of species 2 depletes the resources less than adding an individual of species 1, and vice versa, if alpha is greater than 1.

Answer 262

Both competition coefficients must be less than 1. the worst kind of competitor should be a member of the same species.

Answer 263

K1 > K2α12 AND K2 > K1α21.

Answer 264

When each species has its own ecological niche.

Answer 265

If the environment is more complex than one ecological condition being limiting.

Answer 266

… they cannot coexist.

Answer 267

Observed five different species of warblers in coniferous forests.

Answer 268

Each warbler fed on a different part of the tree. E.g., Cape May warblers fed only on the tops of trees. If any one of these species' populations increased in size, intensified intraspecific competition would mean the species whose population had just increased would suffer the most. Population rescue also occurs as when a species is rare, competition is released, so the species' population increases.

Answer 269

If one of the species went extinct, the other species' populations would still increase, but there may be a delay as the other species are not as sensitive.

Answer 270

… conspecifics.

Answer 271

If species have different niches, then competition is concentrated within a species, and species have a greater impact on themsleves than they do on others.

Answer 272

When the population density of a given species is high, there are high levels of competition that tend to cause the population growth rate to decline. Vice versa when population density of a given species is low.

Answer 273

Constrain species, so they cannot be good at everything. Competition between species through evolutionary time forces them to specialise.

Answer 274

Cacti have spines and photosynthetic stems, but they grow slowly. Whereas, bamboo is defenceless and fast-growing because it grows in montane forests here resources are abundant, so bamboo must grow fast enough to reach the light. Plants with hairy leaves represent a middle-ground as they do have some defence, but the hairs do affect light penetration and, thus, growth rate. The Darwinian demon would be a hairy-leaved bamboo, but this is impossible as resources are limiting.

Answer 275

The resulting trade-offs offer potential niche axes along which species can be differentiated.

Answer 276

Trees that grow quickly in the gaps due to fallen trees, but not well in the shade. Cast a light shade.

Answer 277

At the other end of the growth-survival trade-off to pioneer trees. Can't grow quickly in the gaps, but can survive well in the shade. Cast a dense shade.

Answer 278

Reaches the forest floor.

Answer 279

Pioneer trees. Cannot regenerate in the shade. Produce lots of small seeds. Short-lived.

Answer 280

Shade-tolerant. Larger than birch. Grows slower than birch because the wood is higher density.

Answer 281

When a shade-tolerant tree dies, a large gaps facilitates lots of light. The pioneer tree produces lots of seeds, so it's likely that the pioneer tree will fill the gap. When a pioneer tree dies, the gap is smaller, but shade-tolerant saplings were already growing underneath it in the less dense shade. Though pioneer trees will attempt to outgrow them, the shade-tolerant trees were already there, so will fill the gap.

Answer 282

Tend to have a greater proportion of pioneer trees.

Answer 283

Shade-tolerant trees live longer.

Answer 284

1. When a shade-tolerant tree dies, it creates a gap, which is captured by a pioneer tree. 2. When a pioneer dies, its place is atken by a shade-tolerant tree.

Answer 285

This allows the different species to specialise, so they can co-exist. Other forms of heterogeneity, e.g., different soil types, can also promote the co-existence of plant species.

Answer 286

… there are lots of gaps available, so the pioneer population increases.

Answer 287

… there are lots of pioneer trees, which creates the ideal environment for shade-tolerant trees to grow, increasing their population.

Answer 288

Colonised the Greater Antilles from mainland South America.

Answer 289

E.g., in Cuba, there are 6 main ecomorphs that feed on different parts of the habitat, e.g., crown-giant, grass-bush etc.. The larger islands support more ecotypes. Classified by Losos based on habitat.

Answer 290

The order each morph evolved on each island differs. Their evolution is repeatable.

Answer 291

Competition between species.

Answer 292

Convergent evolution of similar ecological strategies.

Answer 293

Due to E. coli.

Answer 294

7 million.

Answer 295

1.5 million at least as there is a lack of data on low-income countries.

Answer 296

50-60 million.

Answer 297

Sub-Saharan Africa. It is also prevalent in South Asia. Particularly in low-income countries.

Answer 298

One of the biggest killers in low-income countries as it causes neonatal sepsis. It absorbs DNA easily.

Answer 299

When an antibiotic is given that not only selects for a resistance mechanis against that antibiotic itself, but also selects for a resistance mechanism against another antibiotic (or resiatnce to multiple antibiotics).

Answer 300

Genes are clustered together, and move in those clusters. Thus, using antibiotic A also selects for resistance to antibiotics B, C and D due to the cluster.

Answer 301

The bacteria would be unaffected by the switch. This may result in clinical failure.

Answer 302

Biocides, such as those used to clean surfaces in hospitals, and the use of nutrients such as copper and zinc in the farming sector also select for anti-microbial resistance.

Answer 303

… the more foreign DNA it can acquire by homologous recombination. This means the more resistance genes a bacterium has, the more it can acquire.

Answer 304

The cost of antibiotics in Nigeria has risen fourfold since last June.

Answer 305

5-6 newborn babies were sharing a cot and an incubator. The supply chain across many African countries for antibiotics was so poor that there were no available antibiotics to treat Klebsiella pneumoniae in the hospital. Mothers of newborns bought the drug meropenem, and sahred it around the unit to treat sepsis. Neither the mothers nor the hospital could afford it long-term.

Answer 306

WHO, FAO (Food and Agriculture Organisation) and WHO for animals.

Answer 307

10^14 bacteria.

Answer 308

In Bo in Sierra Leone, there is no running water or soap in birthing suites, so infection is high and can spread quickly. There are no hospitals with running water in Ethiopia.

Answer 309

He views hospitals as the battle-ground for infections because bacteria are on and in humans.

Answer 310

Successful at moving large quantities of DNA at no cost to the bacterium.

Answer 311

Can cause DNA to be moved, e.g., plastics.

Answer 312

Genes on the plasmid that hold the bacterium hostage.

Answer 313

Exceeds 200,000 tons per year. Usage is projected to increase by 8-11% by 2030.

Answer 314

$7 billion. Projected to reach $11 billion by 2033.

Answer 315

Barely $1 billion is used to tcakle anti-microbial resistance each year, whereas $2.4 trillion is spent on international arms, even though less than 1 million people have died in conflict since 1985.

Answer 316

Access, Watch and Reserve.

Answer 317

Antibiotics you should be able to get relativley freely.

Answer 318

Antibiotics you should be able to get, but the use of which should be monitored.

Answer 319

Antibiotics that should only be used for life-threatening infections.

Answer 320

Used as a growth promoter in animals, but confers resistance to the antibiotic group carbapenems, which is used in humans to treat serious infections.

Answer 321

Contains colistin, which is used to treat serious infections in humans.

Answer 322

1 in 10^3-10^4.

Answer 323

Plasmid (120-250 kb) have resistance genes arranged in clusters. There's a transfer integron, which contains a cluster of genes, incl. aadA1 (confers resistance to aminoglycosides) and VIM-1 (Confers resistance to carbepenems). If this cluster is transferred, be it onto the chromosome or another plasmid in another bacterium, not just one gene is received, but a series of genes.If treating a patient with carbapenems, VIM-1 confers resistance to it, and aadA1 is transferred as well.

Answer 324

Have an integrase (a recombinase)-encoding gene, a recombination site and a promoter, as well as a gene casette, which may contain anti-microbial resistanec genes.

Answer 325

New Delhi Metallo β-Lactamase. Discovered in 2010. Confers resistance to carbapenems.

Answer 326

In E. coli in eastern China, this plasmid was associated with the resistance gene NDM5. NDM5 confers resistance to carbapenems, but China doesn't use carbapenems. The NDM5 genes were being transferred due to the use of ampicillin in chicken and pigs.

Answer 327

The IncX3 plasmid with NDM5 genes appeared in gram positive bacteria fter mating with plasmid-containing gram negative bacteria. This method was culture-independent, so allowed factors affecting the transfer of plasmids between bacteria and the environment to be observed.

Answer 328

Plotted concentration of plastics (x-axis) against transfer frequency (y-axis). The presence of plastics increases the transfer frequency of plasmids. This links environmental degradation with anti-microbial resistance.

Answer 329

In the gut of chickens, IncX3 with NDM-5 is transferred between bacteria without the antibiotic being applied.

Answer 330

The low-grade antibiotic tetracycline (used in fish, chickens and pigs) is driving resistance to tigecycline via the tetX4 resistance gene carried on a plasmid. ISCRs are resposnisble for the dissemination of tigecycline resistance in E. coli in China.

Answer 331

Mobile Colistin Resistance. Modifies the lipid A portion of the membrane in E. coli and other bacteria.

Answer 332

Colistin was used in farms.

Answer 333

The strains were sick. MCR genes massively affect bacteria by modifying their outer membranes, which is toxic to bacteria.

Answer 334

E.g., Klebsiella pneumoniae can survive with 10% of its genome being foreign DNA.

Answer 335

The toxicity of the MCR genes was tested by using a promoter to over-express the mcr-1 gene, which caused E. coli to burst, and become non-functional.

Answer 336

In April 2017 in China. The European Medicine Agency and America later followed suit.

Answer 337

This wouldn't have worked so effectively with any other antibiotic. This drop was due to the fitness costs of MCR genes.

Answer 338

Index case. MCR genes are present in many plasmids.

Answer 339

It would be full of antibiotic resistance genes and jumping genes. Any bacterium in possession of it would be resistant to all antibiotics on the planet, except the experimental ones.

Answer 340

An organism that does everything well. It lives forever, reproduces frequently and successfully and develops into an adult quickly. If it existed, it would have outcompeted all other species.

Answer 341

Survival, reproduction and development.

Answer 342

close to being a Darwinian Demon, but it doesn't live long.

Answer 343

By optimising trade-offs.

Answer 344

Study of how an organism's traits influence fitness at different stages of its life, from birth to death. Founded by George Williams et al..

Answer 345

Size at birth, growth pattern, age at maturity, number and size of offspring, life span and sex of offspring.

Answer 346

Joeys live in their mother's pouch for months-- tiny and defneceless. Altricial species. Whereas, the Ugandan Kob produces offspring that are abel to run, graze and socialise-- almost independent of each other. Precocial.

Answer 347

Produce ready-to-go offspring. Opposite of altricial. Altricial to precocial is a continuum.

Answer 348

Determinate and indeterminate growth patterns. The sit-and-wait growth pattern. Some species even have a growth pattern of climbing to grow as tall as possible, e.g., Lianas.

Answer 349

Determinate growers finish development and growth at maturity.

Answer 350

Indeterminate growers don't stop growing at maturity, e.g., corals.

Answer 351

Seedling-looking plants can be 50 years old as they are opportunits waiting for a tree to fall, so light becomes available.

Answer 352

Aphids give brith to pregnant daughters, so the age at maturity is in utero. Wheras, the agave century cactus (not a real cactus) can wait 100 years before it reproduces.

Answer 353

The strategy in which organisms only reproduce once, then they die.

Answer 354

Orchids are the plant equivalents of clams with many offspring. Whereas, kiwis produce 1 large offspring in a clutch.

Answer 355

In Crocodilians, this follows a normal distribution, which can be male- or female-biased.

Answer 356

The seven figure pygmy goby that lives for just 3 weeks.

Answer 357

One in the U.S. is 5000 years old. Dated using tree rings.

Answer 358

Has the longest lifespan, if counting from when the propagule (here, the seed) was set. Seeds obtained from the last glacial 32,000 years ago germinated to produce viable plants.

Answer 359

An organism that always returns to breed in the same place.

Answer 360

Can be used to calculate fitness. Individual life history strategies determine population growth rates.

Answer 361

Sum of lxmx across age classes, i.e., the sum of the R column in a life history table is net reproductive success.

Answer 362

The average contribution to the ancestry of future generations made per individual for each age class.

Answer 363

Offspring per capita.

Answer 364

Sx for a particular year/ Sx in year 0. Survival to a particular age.

Answer 365

Like with Covid-19, the contribution of an organism to a population throughout its lifetime. How amny daughters a female has in her lifetime.

Answer 366

The population is stable.

Answer 367

The population is decreasing.

Answer 368

The population is increasing.

Answer 369

Traits of individuals can be used to predict the contribution of individuals to a population in terms of reproduction. These ideas were misused in eugenics.

Answer 370

Age groups where the fish have a low Rv.

Answer 371

The genetic value of males and females is equal because the sex ratio is equal.

Answer 372

When Rv (reproductive value) is maximised. A balance between egg size and egg number.

Answer 373

Rv (reproductive value).

Answer 374

Parent birds tend to sleectively feed the older offspring in tough conditions as they have a higher Rv than the younger offspring.

Answer 375

… parental care.

Answer 376

Much lower than for humans, so an individual offspring is less valuable to its parents.

Answer 377

The structure is 'preyed upon' by fish, so the clam larvae becomes trapped in the fish gills.

Answer 378

Deleterious mutations that are expressed at this age are more likely to be selected out as this is when Rv is highest.

Answer 379

Human females continue to live beyond the point at which Rv drops to 0.

Answer 380

Whenever the grandmother lived in the same area as the mother, the mother's fecundity and the number of grandchildren increased.

Answer 381

The fitness of an individual increases, if the number of its grandchildren increases. Also applies to cooperative breeding, e.g., in wasps.

Answer 382

Stochastic changes in allele frequency (due to chance). Faster in smaller populations.

Answer 383

Causes alleles that confer a beneficial phenotype to increase in frequency, e.g., selection for low body armour in freshwater sticklebacks.

Answer 384

Causes deleterious alleles to decrease in frequency.

Answer 385

Deterministic loss of low-fitness alleles.

Answer 386

… decrease genetic diversity. Mutation increases genetic diversity.

Answer 387

Most mutations were found to eb deleterious, low levels of genetic diversity in populations and occasional rapid selective sweeps by beneficial mutations.

Answer 388

A molecular phenotype of a protein as aminoa cid variation causes proteins to migrate at different speeds.

Answer 389

First used to examine mutations in natural populations, but used proteins instead of DNA. Different charges of proteins affect the distance they move.

Answer 390

Have two bands in allozyme electrophoresis.

Answer 391

Not all mutations change the charge of the protein.

Answer 392

High levels of genetic diversity in populations, e.g., the alcohol dehydrogenase F allele.

Answer 393

Conserved sequences of amino acids indicate descent from a common ancestor. Proteins exhibit a clock-like divergence over time due to mutation. There's a strong correlation between molecular divergence time and fossil divergence time.

Answer 394

Indicate the similarity of a protein from another species to the human version.

Answer 395

The divergence between species, and the polymorphisms within species.

Answer 396

Variation within species and divergence between species is chiefly the result of neutral mutations. Genetic drift drives molecular evolution. Selection at a molecular level is principally a purifying force removing deleterious alleles. Beneficial mutations exist, but they are so rare that they can be ignored.

Answer 397

µ/allele/generation.

Answer 398

Every allele either goes extinct (0) or to fixation (1) due to genetic drift over time.

Answer 399

Allele frequency.

Answer 400

A new mutation starts out as a single copy. Population size= 2N (2 because it's diploid). Frequency of the new mutation= 1/2N. Popbability of fixation by drift = 1/2N. Hence, almost all new mutations are lost.

Answer 401

Slower drift.

Answer 402

Rate of evolution due to drift = rate of appearance of mutations x probability of fixation = 2N*µ * 1/2N= µ

Answer 403

Neutral mutation rate x time (in generations).

Answer 404

Deleterious mutations are removed before they cn contribute to the diversity of the population.

Answer 405

Fixed differences and polymorphisms reflect positive sleection for beneficial mutations.

Answer 406

The vast majority of polymorphisms and fixed differences reflect genetic drift of neutral mutations.

Answer 407

Allozyme electrophoresis (demonstrated high diversity in populations) and clock-like divergence between species.

Answer 408

Indicate mutations in the hemagglutinin gene sweeping to fixation because these mutations allow the virus to escape human antibodies.

Answer 409

Enables the identification of beneficial mutations.

Answer 410

The SARS-CoV-2 genome was modified to have this mutation, then grown on plates to measure replication in the mutated strain compared to a non-mutant. An example of functional characterisation of mutations.

Answer 411

The same mutation is fixed in different populations. More parallel evolution than expected by chance alone (as genetic drift fixes mutations and is stochastic) is indicative of positive selection.

Answer 412

A single clone of E. coli was grown in a tube deficient in nutrients for 24 hours. The some of the E.c oli is trasnferred to the next tube. This process repeats. There have been 12 separate repeats of this whole experiment since 1988. Some of the E. coli was cryogenically frozen, so could be sequneced later.

Answer 413

The same genes with different utations had similar consequences. E.g., the ribose gene was knocked out due to different mutations in each population as there was no ribose in the medium for E. coli to catabolise.

Answer 414

The exact same mutation in the monarch butterfly, red milkweed beetle, large milkweed beetle and Oleander aphid that affects the Na+/K+ pump confers resistance to the milkweed toxins. It's not just the same gene; it's the same nucleotide substitution across the 4 different species.

Answer 415

Requires a statistically null hypothesis-- how much is due to random genetic drift? It's good at picking up genes that are under strong selection, but doesn't capture a lot of adaptation.

Answer 416

Typically in the 3rd position in the codon. Don't change the amino acid. Likely to be neutral. Indicate the effects of random genetic drift.

Answer 417

Change the amino acid and protein. May be neutral, deleterious or beneficial. Indicate the effects of selection.

Answer 418

Rate of non-synonymous substitutions.

Answer 419

Rate of synonymous substitutions.

Answer 420

6 million years of divergence. 45% of non-synonymous differences are due to positive selection. 270,000 selected differences with one selective sweep every 45 years.

Answer 421

30-1% of non-synonymous differences are due to positive selection.

Answer 422

Over time, as the less closely-related species have diverged longer ago, the dN will be swamped by the dS as there have been so many synonymous mutations.

Answer 423

It only picks up genes under recurrent selection.

Answer 424

What would genetic variation look like without selection?

Answer 425

New traits that allow organisms to exploit their environment in new ways. Important in the context of major transitions and individuality.

Answer 426

Proteins are dynamic with conformational flexibility. Enzymes have a primary reaction that they catalyse, as well as another ligand that can bind to it in a less-preferred conformation.

Answer 427

A mutation can mean that the enzyme switches, so that its less-favoured reaction becomes the primary reaction that it catalyses.

Answer 428

Mutagenic PCR of a gene. Artificially select for E. coli that best produce the protein encoded by the gene of interest. Repeat the PCR amplification.

Answer 429

A gene (FleQ) was deleted. This meant the FleQ regulator wasn't produced, so the flagellar operon wasn't transcribed. Within 1 week, they had re-evolved the ability to grow a flagellum. Mutations switched the NtrC binding, so the Tf could bind to and regulate both the flagellar structural genes and the nitrogen assimilation genes. Eventually, it evolved only to regulate flagellar structural genes.

Answer 430

They couldn't swim, so used up their resources.

Answer 431

HGT. Plasmids are semi-autonomous DNA molecules that are replicated and transferred across the conjugation pilus. Plasmid genes can be incorporated into the bacterial chromosome.

Answer 432

Up to 90% of some bacterial genomes come from HGT. the lac operon genes were inly recently acquired by E. coli via HGT.

Answer 433

Plasmids carry antibiotic resistance genes from environemntal bacteria into gut bacteria in the gut microbiome.

Answer 434

Have acquired genes for protection against fungal pathogens.

Answer 435

Acquired from bacteria, liekly very early in eukaryotic history.

Answer 436

Hypoxia-induced. Enables adaptation to low-oxygen on the Tibetan plateau. This allele was acquired from the Denisovans via hybridisation.

Answer 437

The origin of new genes is thought to be gene duplication. Duplications occur just as frequently as mutations at a single site do.

Answer 438

Duplication relieves the selective pressure on the gene. There is amutation in one of the duplicated genes. Duplication means the fucntion of the original gene is retained, and a new function is acquired.

Answer 439

Duplication and divergence.

Answer 440

… determining the distribution and cahracteristics of ecological communities at the global scale.

Answer 441

Higher at the equator. Lower near the poles. Variation within a latitudinal band due to topology and elevation.

Answer 442

The wettest areas on Earth areWest africa, tropical rainforests in South America and Southeast Asia.

Answer 443

Temperature and precipitation.

Answer 444

Zones dominated by plants with characteristic shapes, forms and physiological processes.

Answer 445

The U.S. west coast, the tip of South Africa and parts of Australia due to similar cliamte with high light levels and propensity to drought. E.g., Garrigue in southern France, Chapparal in California and Fynbos in South Africa.

Answer 446

Plots different biomes, e.g., tundra, on a graph with annual precipitation (y-axis) against average annual temperature (x-axis).

Answer 447

Low shrub vegetation at high latitudes. Relatively species poor.

Answer 448

At the equator in Tanzania. From the lowest to the highest elevation: civilisation, rainforest, moorland, alpine desert and eternal ice.

Answer 449

Rate of energy production per unit area. Can also be measured as mass of carbon, or dry organic matter.

Answer 450

The biomass produced by consumers.

Answer 451

The total fixation of energy by consumers. Some of the GPP will be lost as heat due to respiration by the autotroph, but that which isn't lost is Net Primary Productivity (NPP).

Answer 452

The ocean.

Answer 453

Almost 20%.

Answer 454

Have higher annual NPP than tropical rainforests, but cover a smaller surface area.

Answer 455

Tropical rainforests and surrounding Savannah. It’s also quite high in temperate zones, too.

Answer 456

The intensity of solar radiation received, the availability of water, tempearture and the availability of nutrients.

Answer 457

23.8%, of which 53% is from harvesting (this includes plats for feeding livestock, as well as harvesting crops and timber), 40% is from land-use-induced productivity changes and 7% by human-induced fires.

Answer 458

Earth's tilting. Seasonal variation.

Answer 459

Coniferous forests. Higher than in deciduous forests or deserts. Plants in different regions have different degrees of efficiency in using this solar radiation.

Answer 460

Away from the equator.

Answer 461

Water is inaccessible as it's locked up in snow and ice. There's also less light in winter. Productivity is only possible when plants can photosynthesise.

Answer 462

Phosphorous and nitrogen.

Answer 463

The soil has been weathered, and iron-oxide in the soil tends to bind to phosphorous, limiting its availability.

Answer 464

Nitrogen is limiting, or both nitrogen and phoshporous are co-limiting, except for in tropical regions and/or rainforests where phosphorous is limiting.

Answer 465

Have shallow gradients and high productivity. Impacted greatly by humans.

Answer 466

4-5 km down. Little is known about it.

Answer 467

Seafloor spreading at a constructive plate boundary. Volcanically active areas. Can include depp-sea vents.

Answer 468

Driven by the heat and chemical gradients of Earth instead of by sunlight. Source of critical minerals.

Answer 469

When the plume of magma is separated from the vent, it sinks to form a seamount.

Answer 470

Form islands.

Answer 471

Transition layer between the warmer surface waters and the coller waters below. Sharp reduction in temperature down to 1000m deep. It then remains that temperature until the abyss. Established in the tropics (permanent feature here) and in summer at temperate latitudes. Less-dense warm water prevents vertical mixing, leading to nutrient depletion in surface waters.

Answer 472

40x less. It also diffuses ~1,000x slower.

Answer 473

~200m -1,500m. Respiration exceeds photosynthesis and diffusion of O2 from the air. O2 is less oluble in water than CO2.

Answer 474

Due to waves that can mix the entire water as the water is shallower.

Answer 475

Sea level-200m deep. Only zone in which photosynthesis occurs, and most of it in the top 50m, as sunlight seldom penetrates beyond this zone. Home to tuna.

Answer 476

200m-1000m deep. Sunlight decreases rapidly with depth. Photosynthesis is not possible here. Home to shrimp, hatchet fish and swordfish.

Answer 477

Below 1000m deep. No light penetration at all. Home to giant squid, angler fish and tripod fish.

Answer 478

Blue-green.

Answer 479

More turbidity due to river mouths.

Answer 480

~1/3. It is estimated that ~1/2 of current emissions continue to be absorbed.

Answer 481

Seawater reacts with water to produce carbonic acid that dissociates into bicarbonate ions and H+ ions. These additional H+ ions react with existing carbonate ions in the water forming further bicarbonate.

Answer 482

They rely on saturating concentrations of carbonate ions. At a pH below 7.5, this becomes critical.

Answer 483

Temperature gradients and wind.

Answer 484

Carries warmer water from the Caribbean to the UK.

Answer 485

Creates dense, hypersaline water as the ice is pure, salt-free water.

Answer 486

Redistributes nutrients. Slow-moving currents. As deep water flows, it picks up nutrients from the bottom of the ocean, bringing them to the surface. This fuels hotspots of productivity.

Answer 487

Virtual deserts. Lack of primary productivity due to the permanent thermocline under the constant sun.

Answer 488

50 billion tonnes of crabon are fixed every year.

Answer 489

1. Bacterioplankton (30-50%): cyanobacteria. 2. Phytoplankton. 3 major groups: the diatoms, the dinoflagellates and the coccolithophores.

Answer 490

Bacteria and archaea.

Answer 491

… 5x the biomass of producers.

Answer 492

2 Gt of protists, 2 Gt of animals, 0.5 Gt of plants and 1.5 Gt of bacteria.

Answer 493

Typically longer than terrestrial food chains due to more efficient energy transfer. Food chain length can vary hugely, e.g., upwelling that support large phyotoplankton communities enable lots of grazing by fish etc..

Answer 494

The coast/continental shelves, and the Arctic. Hence why lots of animals migrate to the Arctic.

Answer 495

Recycles dissolved organic matter (DOM) in the surface waters.

Answer 496

The prevalence of viruses in seawater-- up to 10 million per ml of sewater.

Answer 497

1000m every 24 hours. They transfer carbon from the surface to the bottom of the ocean by moving up to eat and down to defecate. This is part of why human-emitted CO2 is dissolved in the oceans. The zooplankton excrete tiny faecal pellets that form particuklate organic matter (POM) that sinks, but nutrients are rapidly returned by heterotrophic bacteria.

Answer 498

Absence of a thermocline in winter. Strong vertical mixing.

Answer 499

A major peaks occurs in spring, often followed by a second smaller peak in autumn.

Answer 500

Rarely CO2. Often light in temperate and polar regions.

Answer 501

Most heavily exploited fish worldwide.

Answer 502

Longshore winds on the western edges of continents draw up the cold, nutrient-rich water from the deep.

Answer 503

Upwellings of nutrient-rich water. Common along the west coasts of continents, e.g., on the west coasts of California, Chile and Peru.

Answer 504

~ 60% of the human population, i.e., 4 billion people.

Answer 505

El Niño bringing warm water.

Answer 506

Lie above the continental shelf, highly productive due to strong vertical mixing, heavily exploited and heavily polluted, e.g, agricultural runoff creates dead zones that expand each year, and oil spills are a constant threat.

Answer 507

At mid-latitudes. They are ecologically unstable, and sensitive to harvesting of key animals.

Answer 508

It is harvested directly, and supports important fish, such as rockfish in the U.S. and shellfish such as European lobsters.

Answer 509

Not true plants.

Answer 510

True plants.

Answer 511

A multicellular, brown algae with no true vascular system. Often annual.

Answer 512

Laminaria and Macrocystis.

Answer 513

A holdfast, stipe and baldes.

Answer 514

Macrocystis can grow up to 30cm per day to a height of 30m, forming a dense underwater forest.

Answer 515

Supports epiphytes, e.g., red algae.

Answer 516

40-180 species around the UK. Supports many invertebrate species such as brittle stars, anemones, crabs and jellyfish.

Answer 517

It has very high C:N ratio, and conatins compounds that deter grazers.

Answer 518

Specialist grazer of kelp. Found at low tide in the UK.

Answer 519

Grazers of kelp that specialise on eating their holdfasts. If present in large enough numbers, they can prevent kelp from regnerating after a disturbance.

Answer 520

Macrocystis pyrifera: supports important crab, lobster, abalone, snail fisheries and kelp harvesting.

Answer 521

A major, largely temperate coastal ecosystem.

Answer 522

Constructed a food web based on 10 years of monitoring of 40 different functional groups. Bottom-heavy biomass pyramid. Estimated throughput: 5477.6 t.km^-2. year^-1.

Answer 523

High population density of urchins converts a kelp forest into an urchin barren.

Answer 524

They have very high reproductive rates, so can increase in population density quickly. Often top-down controlled.

Answer 525

Enhydra lutris. Feed on shellfish and echinoderms. Hunted fo fur until 1911, when hunting of sea otters was banned,a nd their population had plummeted to just 2000 individuals.

Answer 526

As their population recovered and their range expanded, sea otters controlled the urchin population, allowing kelp forests to recover.

Answer 527

Warmer waters, strong El Niño events that blocked coastal upwellings (this was an issue as kelp requires a constant supply of nutrients from deep water-- bottom-up control) and a disease of the sunflower sea star.

Answer 528

Target medium-sized urchins. Even when the seastar population collapsed, otters helped to control the urchin population.

Answer 529

Mangroves, seagrass meadows and coral reefs.

Answer 530

They are both dominated by angiosperms. Both have high biomass of primary producers, but not many producer species, and actively sequester huge amounts of carbon.

Answer 531

They have both bottom-up and top-down controls on their productivity.

Answer 532

Overfishing, coastal pollution and rising sea temperatures.

Answer 533

Coral reefs have a much higher number of producer species.

Answer 534

Angiosperms that grow in coastal brackish or saline habitats.

Answer 535

Rhizophora.

Answer 536

They have lenticels (pores for gas exchange) or pneumatophores (act as conduits to provide O2 to the roots).

Answer 537

Salt is mostly excluded by the roots. Some species have the ability to excrete salt via specialised glands in their leaves.

Answer 538

In both temperate and tropical regions. Temperate bed are typically species-poor, and often dominated by eelgrass (Zostera marina). Tropical beds are more species-rich.

Answer 539

72 species.

Answer 540

Alage have a holdfast to attach to a surface, whereas seagrass have roots and a vascular system, so can take up nutrinets from the sediment.

Answer 541

Rhizomes enable asexual reproduction.

Answer 542

No stomata, but athin cuticle. They can produce pollen and seeds, and they can flower. Flowers are pollinated by Crustaceans.

Answer 543

Sirenians (dugongs and manatees) and green sea turtles, which have green flesh as all they eat is seagrass.

Answer 544

Up to 50m deep, but mostly < 30m.

Answer 545

Have a guerilla strategy: they can colonise new areas as they are fast-growing, and have a seed bank to disperse seeds.

Answer 546

Phalanx strategy. Fewer, larger seeds. Grow more slowly, and have larger leaves, so they're better competitors, and better at holding down space.

Answer 547

High biomass systems with high productivity. Important nursery grounds for commercially crucial fish species. Grow in coastal areas, incl. the intertidal zone. Can cope with brackish water and some water turbidity.

Answer 548

They protect the reefs by trapping sediment, and gain protection from wave action as reefs absorb the energy from the waves.

Answer 549

Mangroves filter and trap sediment, so light can reach coral reefs.

Answer 550

The water column stays free.

Answer 551

If they respond to addition of nutrients.

Answer 552

If herbivores affect the seagrass biomass.

Answer 553

Bottom-up: if only seagrass was present, then seagrass biomass increased with nutrient addition. Top-down: if there were no predators, so only seagrass and herbivores, then the response to nutrient addition was dramatically reduced. If all three were present (full food web), predators controlled teh herbivores, allowing seagrass to mop up excess nutrients.

Answer 554

Caging can be sued to kepe predators or herbivores out of the seagrass ecosystem.

Answer 555

Successional sequence: 1. Bare areas with a coarse, sandy substrate, often brought by an estuary. 2. The seagrass starts to colonsie the bare area, and traps silt and sediment. 3. After >40 years, established areas of seagrass with 90cm-thick silt and pools created by burrowing crabs. Climax community: seagrass and crabs.

Answer 556

Primary Habitat Modifier: seagrass. Secondary Habitat Modifier: the burrowing crabs. Removing habitat modifiers impacted species richness at differents tages of the successional sequence.

Answer 557

Mangroves and seagrass meadows.

Answer 558

50-90%, depending on vegetation type.

Answer 559

Tidal inundation keeps the soil wet or submerged, inhibiting microbial action and slowing decomposition. The roots penetrate deep into the substrate, trapping carbon such as in the form of decaying matter. The fine particles of silt create an anoxic environment in which organic matter doesn't decompose. Destroying coastal wetlands would release lots of CO2 into the atmosphere.

Answer 560

Can't store carbon as long-term as coastal wetlands.

Answer 561

Different to tropical coral reefs. Found in cooler waters.

Answer 562

Coral is sensitive to feshwater and silt.

Answer 563

The Indo-Pacific and tropical west Atlantic. The Indo-pacific has ~10x the biodiversity of the west Atlantic.

Answer 564

high light intensity, so low turbidity and oligotrophic waters. Clear waters, temperatures 18-30°C and no sudden changes in salinity.

Answer 565

Coral reef that starts growing on the shore of a high volcanic island in shallow water.

Answer 566

Forms from a fringing reef that is pushed upwards and outwards by tehd eposition of sediment, as the island begins to erode and shrink.

Answer 567

As the volcanic island continues to erode, the lagoon between the barrier reef and the volcanic island becomes wider and deeper. The peak ultimatley sinks below the water, leaving only the encircling reef behind.

Answer 568

Scleractinian corals within the class Anthozoa within the phylum Cnidaria. The ectoderm contains cnidocytes (stinging cells), the endoderm often contains photosyntehtic algae and in-between is the mesoglea.

Answer 569

Photosynthesis may aid the calcification process.

Answer 570

Corals compete for space, so corals attcak each other with their stinging tendrils at night.

Answer 571

Protective CaCO3 skeleton.

Answer 572

Tissue that connects a coral colony. Coral colonies can grow for years, or even decades. Coral can also exist as polyps.

Answer 573

Photosynthetic dinoflagellate algae belonging to the genus Symbiodinium.

Answer 574

Specialised membranous structures that separate the symbiont celsl from the host cytoplasm.

Answer 575

Up to 30%. Can slo be found free-living at low density in tropical waters.

Answer 576

Protection and CO2 from respiration.

Answer 577

Much of its carbon and nitrogen (when not enough is obtained from heterotrophy). It also aids the calcification process.

Answer 578

The symbiont produces amino acids from dissolved inorganic nitrogen (DIN) form the water column and nitrogenous waste produced by the coral.

Answer 579

More than 80%.

Answer 580

Nitrogen-fixing bacteria involved with coral. Its role is unknown as yet.

Answer 581

Many different types of algae are found on reefs such as coralline red algae, fleshy green algae and brown algae. Graizng fish are herbivorous, e.g., sturgeonfish, which, in turn, support predatory fish.

Answer 582

Despite taking up only 1% of the ocean floor, they support 25% of marine life.

Answer 583

Starts by targeting top predators, such as groupers and sharks, but these are easily overfished. Then fishing down the food chain begins: smaller, herbivorous fish such as parrotfish are targeted.

Answer 584

Chronic overfishing, sea urchin boom, hurricane damage and sea urchin die-off.

Answer 585

Began by targeting predatory fish, then moved in to herbivorous fish, incl. parrotfish. Parrotfish tend to feed on fleshy algae that grows in-between the coral. The algae and coral compete for space, so if the algae grow tall, they will block the light from the coral.

Answer 586

Massive numbers of long-spined urchins, Diadema antillarum, kept the fleshy alage in check, depsite the loss of herbivorous fish.

Answer 587

Destroyed much of the Acropora cervicornis species in 1980. There was a short-lived coral recovery afterwards.

Answer 588

1982-84. A pathogen caused the death of 995 of urchins. No herbivorous fish or sea urchins to keep the algae in check. Huge nutrient run-off as well. The benthic algae grew out of control, so the coral couldn't recover.

Answer 589

The reaction of coral to sudden but prolonged high temperatures. Corals expel their symbionts. UV also contributes. Corals don't always die due to bleaching, but if the warming is prolonged, they cannot recover. Some algae grows on the surafce of the bleached coral.

Answer 590

Unclear as yet. It could be because the symbionts become selfish by stopping exchanging nutrients with the coral, or could be due to oxidative stress as the Symbiodium produces reactive oxygen and nitrogen species.

Answer 591

Reefs can exist in one of two stable states (e.g., reef-building coral or fleshy algae, hard coral or macroalgae).

Answer 592

Stronger management of fisheries, and reduced nutrient run-off. Caribbean reefs have still not recovered.

Answer 593

Destroyed reefs around the inner islands. They have not recovered.

Answer 594

Part of a large-scale climate phenomenon that occurs every 3-8 years, and takes months to spread across oceans. In addition, ocean temperatures are rising.

Answer 595

Half of the Great Barrier Reef has been bleached to death since 1995. the average interavl between bleaching events has halved between 1980 and 2016. There were bleaching events in 2017 and 2020.

Answer 596

UNESCO World Heritage Site. Zero commercial fishing. Some corals are adapted to warming and are resistant to bleaching as it's already a thermally intense environment. Reduced coral bleaching, and faster recovery. Some coral that have experinced bleaching appaear to be more resistant to subsequent bleaching.

Answer 597

Trends in the distribution of species across Earth's surface. Macroecology: species curves and latutudinal gradients.

Answer 598

How the number of species recorded increases as the area studied increases.

Answer 599

The trend towards increasing diversity as you move from the poles towards the tropics.

Answer 600

It tends to follow a power function.

Answer 601

… leads to a doubling in the number of species recorded.

Answer 602

Species area curves (log S= z log A + log c) is one of the few genuine laws of ecology.

Answer 603

On islands of different sizes within an archipelago, for pieces within a single biome, e.g., states within the U.S. and for interprovincial areas, e.g., continents.

Answer 604

H. C. Watson in 1859.

Answer 605

1. The habitat diversity hypothesis. 2. The passive sampling hypothesis. 3. The equilibrium hypothesis. These are not mutually exclusive, but they do emphasise different processes.

Answer 606

If there is a wider range of habitat types, more species can live in the area. Larger areas have more habitats, and species idversity increases with habitat diversity.

Answer 607

Keep habitat constant, and vary the area within sampling sites, or keep area constant, and vary habitat within sampling sites.

Answer 608

Larger mangrive islands still have more species than smaller mangrove islands, even though habitat diversity is the same. Thus, habitat diversity doesn't always explain this pattern.

Answer 609

Often used as a 'null model'. Assumes the probability a species is present on a island is proprtional to the island's area, and that islands sample individuals randomly and independently.

Answer 610

Fails to explain the diversity on small islands. Nothing limits diversity: given time all species should be present on an island. Doesn't predict the turnover of species over time.

Answer 611

Some species go extinct, some species arrive, hence the composition of species changes over time, even if still in equilibrium.

Answer 612

Closer islands will have more species than more isolated islands. Larger islands will have more species than smaller islands. MacArthur and wilson (1963, 1967). The number of species on an island would be a fucntion of its isolation and area.

Answer 613

Evolution doesn't influence species richness. Isolated islands are less likely to be colonsied. Large islands have large populations. Large populations are less likely to become extinct. Colonisation and extinction are independent of the species composition of the island.

Answer 614

On a very isoalted oceanic island, e.g., the Galapagos where independent radiations within the archipelago have occurred, divergence leading to speciation may occur.

Answer 615

1. There should be substantial turnover in species composition, but species number should remain relatively constant over time. 2. All else being equal, the number of species on an island should decrease with increasing isolation.

Answer 616

As per the Equilibrium Hypothesis, species richness was stable, but there was significant turnover in species composition.

Answer 617

Defaunation: they killed off the invertebrates living in mangroves. Invertebrate species tehn recolonised from other islands. ~2 years later, the number of species reached the pre-defaunation number. This demonstrates hoe the number of species reaches a plateau.

Answer 618

Used to predict how many extinctions will occur following area reduction, and to suggest the best way to slow the loss of spceis by reserve design.

Answer 619

Species richness is the main object of conservation, and that varaition in area is the main cause of species richness.

Answer 620

The gardient of the line for a species area curve on log axes. The steeper the slope, the more rpaid the cahneg in species richness. For a given reduction in area, the graph indicates the corresponding change in species richness.

Answer 621

52% of forest in eastern North America have been cleared in the past 200 years. Species-area relationships predicted a loss of 4.8 endemic species. 4 have gone extinct with a fifth species close to extinction.

Answer 622

Size matters: larger areas have more species. The SLOSS controversy: should you have a single large reserve or several smaller reserves with a similar area?

Answer 623

The number of species on an individual island.

Answer 624

The number of species across the whole archipelago.

Answer 625

Gamma diversity / alpha diversity. The turnover of species in space (previously, it was turnover over time). A measure of the differentiation of communities.

Answer 626

The degree to which species overalp between different areas. Many smaller islands or reserves can collectively have more sepcies than a larger, equivalent area.

Answer 627

At the equator.

Answer 628

At the North Pole and -90 is the South Pole.

Answer 629

… are tropical.

Answer 630

Cover 7% of the Earth's surface. Account for >50% of Earth's biodiversity.

Answer 631

… different levels of the taxonomic hierarchy, e.g., genera, family etc..

Answer 632

Penguins (have higher species richness at the poles) and ichneumoid wasps.

Answer 633

Biotic explanations, e.g., productivity, competition and predation. Abiotic explanations, e.g., time and stability.

Answer 634

A greater arnge of possible resources. Each species is more specilaised. More overlap in reosurce use. Resources are more fully exploited.

Answer 635

Many of the explanations are circular, many explanations make similar, qualitative predictions, the data is often messy (from many sources), our sample size is small (1 planet) and doing experiments is difficult.

Answer 636

Productivity or Species Energy Hypothesis. The hottest, most humid places have the greatest net primary productivity. More resoucrsx can support more posisble species.

Answer 637

Tropical seas have low productivity, but high richness. Eutrophic lakes have high productivity, but low richness. High productivity doesn't always lead to high abundance or biomass.

Answer 638

Similar resources, but each species is more specialised. If niches are narrower, more species can be packed into an environment. Constant climate and intense competition in the tropics leads to niche narrowing. Most species grow towards tehir carrying capacity.

Answer 639

Comparative analysis of strength of competition and niche breadth are difficult.

Answer 640

Due to less intense interspecific competition. More intense mortality in the tropics due to natural enemies, instead of predators. Predator-mediated co-existence: population sizes of tehir prey are kept low, which reduces competition. This allows overlap in resource use, prevents any one species becoming locally dominant. Thus, many species can co-exist.

Answer 641

Communities diversify over time, and temperate regions are younger due to glaciation. Tropics have been relatively unchanged for at least 1.5 x 10^8, and display low seasonality. There are empty niches outside the tropics, but there has been no ecological time for species to re-invade, or evolutionary time for species to evolve to fill them.

Answer 642

Many exceptions where stable habitats have low diversity, e.g., tropical mountain tops. The deep ocean is a constant ocean with a low number of species. Many tropical environments have seasonal fluctuating environments.

Answer 643

At this scale, the number of species is a balance between speciation rates and extinction rates. Species present = species evolving - species going extinct.

Answer 644

Lower extinction rates due to their larger populations and refuges they provide agianst environmental change. Increased speciation rates as geographic barriers facilitate allopatric speciation, and the greater chance of a rare mutation leads to more rapid evolution.

Answer 645

Only 0.8% of Earth's water is a suitable freshwater habitat. Only 2% of the Earth's surface is freshwater, but much of that is locked up in permafrost and glaciers.

Answer 646

Lake Baikal in Russi is the deepest freshwater lake, and is home for the only species of freshwater seal. By contrast, hot springs, e.g., Hengill in Iceland are small and can be up to 100°C.

Answer 647

Incl. microbes such as diatoms. Freshwater habitats are home to 25% of described mollusc species. 55% of fish species reside in freshwater for at least part of their lifecycle.

Answer 648

Native: 38. Introduced: 12.

Answer 649

Up to 1,000.

Answer 650

For animals, the number of species per km^2 in freshwater habitats is more than double that of terrestrial habitats. Phylogenetic diversity of terrestrial species also exceeds terrestrial species.

Answer 651

Since 1970, the population decline of freshwater vertebrates is 84% compared to 30-40% in marine and terrestrial ecosystems.

Answer 652

Benefits to humans from the natural environment. Freshwater habitats provide drinking water, fish protein and flood protection.

Answer 653

Thousands of insect and bird species. 6 orders of mammals.

Answer 654

Sirenia: manatees, the freshwater manatee is the smallest species of manatee and lives in the Amazon. Cetartiodactyla: dolphins and hippos. Carnivora: otters, minks and seals. Rodentia: beavers, capybara and voles. Eulipotyphyla: shrews. Monotremata: platypus.

Answer 655

These orders are spread out across the phylogenetic tree.

Answer 656

Bacteria, viruses and fungi. Live in hot springs. E.g., Hydrogenobaculum and brine flies.

Answer 657

Such as those in Yellowstone that are more acidic than a car battery.

Answer 658

Darkness, little food and low oxygen.

Answer 659

No scales, for efficient swimming, and no eyes in cave morphs, unlike the surface-dwelling morphs.

Answer 660

Cave dwellers have lower metabolism and increased red blood cell development.

Answer 661

4 Ds: dormancy, diapause, die young (live fast) and dispersal.

Answer 662

Adult rotifers can have an inert body form with almost no body water. When rehydrated, they resume activity within a few hours.

Answer 663

In crustacean zooplankton (e.g., cyclopoid copepods), they can produce a different kind of eggs that can undergo diapause when they sense a stress. The eggs can survive for up to 200 years in this state. When rehydrated, the eggs hatch.

Answer 664

Many species have aquatic larval and terrestrial adult stages. E.g., mayflies and dragonflies. The insects use the temporary pools for their larvae, which then emerge as flying adults.

Answer 665

The Turquoise killifish is the fastest-living fish. Lives in the Zimbabwean Savannah. Adults live for 3-9 months and reach sexual maturity as quickly as two weeks-- the fastest of any vertebrate.

Answer 666

Once maturity is reached, females lay 20-120 eggs per day, which are then fertilised by a male. When the pool dries up, adults die, but the dormant embryos are left behind. When the rainy season begins, they rapidly hatch, growing from 5 to 30-50mm in a few weeks.

Answer 667

Present an issue for migratory fish.

Answer 668

Uses a sucker mouth to climb waterfalls.

Answer 669

Freshwater habitats occupy the lowest point in the environment. Thus, whatever occurs in the surrounding catchment accumulates in the freshwater environment.

Answer 670

they can have ripple effects on food chains, and result in biomagnification as toxins are concentrated in tissues when travelling up the food chain. Biocides incl. insecticides, herbicides, pesticides and fungicides as well as antibiotics often end up in freshwater, especially in the lowland catchments and floodplain's of the world's major rivers, which are often densely-populated.

Answer 671

Also poisonous to fish.

Answer 672

Because it's spread out across fields then enters the river at multiple points.

Answer 673

Heatwaves and raw sewage combined to increase the spread of cholera.

Answer 674

Pollution from nutrients. Two main sources: sewage and fertiliser.

Answer 675

Elevated nutreients due to organic pollution promote algal growth. As the alage decompose, microbes deplete the O2 in the water. Invertebrates and fish perish, or leave the affected area.

Answer 676

They also impair sediment transfera nd migratory fish.

Answer 677

37%. Uninterrupted rivers are restricted to the Arctic, the Amazon and Congo basins.

Answer 678

If demand exceeds supply. The combined effect of climate change and increased demand leads to dry rivers.

Answer 679

By water usage and fisheries.

Answer 680

… globalisation.

Answer 681

Leaf litter that falls into streams is an important food source for aquatic invertebrates. Leaves from innvasive plants may be less palatable. E.g. rhododendrons don't provide sufficient food for native species.

Answer 682

Are outcompeting native crayfish by bringing disease. In the UK, there's 1 native and 6 invasive species of crayfish.

Answer 683

Some sites are no longer suitable for species with a narrow thermal niche. Fragmented habitats mean individuals often cannot move.

Answer 684

Flooding changes nutrient dynamics, availability of seasonal resources and habitat availability.

Answer 685

Some evidence suggest fish activity decreases with warming.

Answer 686

Mitigate, amplify or additive effects.

Answer 687

The sum of the mortality of each of the stressors.

Answer 688

Antagonistic interaction between stressors mean the overal effect is less than the sum of its parts.

Answer 689

Synergistic interaction between stressors. The overall effect is more than the sum of its parts.

Answer 690

Non-additive effects are common.

Answer 691

Fishing pressure, invasions and pollution. Nutrient pollution has promoted the spread of invasibe floating hyacinth. Native fish have lower fitness from pollution, which means they are more likely to get caught in the growing fishery.

Answer 692

Warming can increase the potentcy of some pollutants, but can aso decrease the effects of pollutants by breaking them down faster.

Answer 693

… of a species to subsequent stressors.

Answer 694

One species will only be lost in instances of plant invasions. The other species will only be lost when fish invade. Different parts of the food web are affected, so the effect of the stressors can be summed. This si because stressors are quite different.

Answer 695

One species isn't sensitive to either invasion (both invasions are by fish, but different species). The other species is senitive to both invasions. Antagonistic effects: its' non-additive. Less than the sum of its parts. For the affected spcies, it doesn't matter if it;s one spcies of both invading.

Answer 696

Stressor similarity. Stressor similarity can be used to predict whether the effects of the interacting stressors will be additive or non-additive.

Answer 697

They could be insecticide and an invasive insectivorous fish, for example.

Answer 698

Altered interactions between species, e.g., competition, parasitism and predation. Perch has restructured the Lake Victoria food web by causing extinctions. After the effects of the null perch, stressors are starting from a different baseline.

Answer 699

~90% of all lowland rivers in the study area were imapcted bya combination of all 4 pressures.

Ecology and Evolution Flashcards

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