Other questions

Question 1

What are indirect effects in a food web?

Answer 1

The impact of one organism or species on another that is mediated or transmitted by a third

Question 2

What is a species interaction?

Answer 2

The outcome of two individuals coming in to contact

Question 3

What is interaction strength?

Answer 3

The degree to which a species location in a food web structure is dependent on a given interaction with another species.

Or, the strength of an interaction is the relative change caused by severing that interaction.

Question 4

What is a classic example of indirect effects in a food web?

Answer 4

The removal of otters from the kelp forest community lead to a loss of kelp through an overabundance of sea urchins.

Question 5

How has research on trophic cascades advanced our knowledge of community ecology?

Answer 5

Trophic cascades help model the combined direct and indirect effects of a community, as well as the transition between community states.

Question 6

What is top down forcing? Give a strong piece of evidence for it.

Answer 6

Predators shape community structure. E.g. otters

Question 7

What is bottom up forcing? Give a strong piece of evidence for it.

Answer 7

Resources can limit the abundances of species at higher trophic levels. E.g. seagrasses

Question 8

Imagine you have a long time series of monitoring data from the same transect on primary producer, herbivore, and predator abundance. Explain how you might infer if the system was under top-down or bottom-up control.

Answer 8

You could track the relative abundances of each and look for time lags in response to stochastic events that affect the primary producers and predators.

Question 9

What is the functional response in consumer-prey relationships?

Answer 9

Can be Type I, II or III.

Type I: Linear density of prey: prey consumed

Type II: Decelerating intake rate, which follows from the assumption that the consumer is limited by its capacity to process food (rectangular hyperbola)

Type III: Accelerating intake rate

Question 10

Why is ocean acidification worse in colder waters?

Answer 10

CO2 is more soluble in cold water,

Question 11

Describe the Lotka Volterra model.

Answer 11

A pair of first-order, nonlinear, differential equations frequently used to describe the dynamics of biological systems in which two species interact, one as a predator and the other as prey.

Question 12

What is the difference between a fundamental and realized niche?

Answer 12

Fundamental niches represent all the environmental conditions where a species is able to live, and the realized niche is where the species actually lives. Other names for these niches are precompetitive and postcompetitive, respectively.

Question 13

Describe the three survivorship curves.

Answer 13

Type I or convex curves are characterized by high age-specific survival probability in early and middle life, followed by a rapid decline in survival in later life. They are typical of species that produce few offspring but care for them well, including humans and many other large mammals.

Type II or diagonal curves are an intermediate between Types I and III, where roughly constant mortality rate/survival probability is experienced regardless of age. Some birds and some lizards follow this pattern.

Type III or concave curves have the greatest mortality (lowest age-specific survival) early in life, with relatively low rates of death (high probability of survival) for those surviving this bottleneck. This type of curve is characteristic of species that produce a large number of offspring (see r/K selection theory). This includes most marine invertebrates. For example, oysters produce millions of eggs, but most larvae die from predation or other causes; those that survive long enough to produce a hard shell live relatively long.

Question 14

What is life table analysis?

Answer 14

A table which shows, for each age, what the probability is that a person of that age will die before his or her next birthday.

Question 15

What is the source-sink model?

Answer 15

In this model, organisms occupy two patches of habitat. One patch, the source, is a high quality habitat that on average allows the population to increase. The second patch, the sink, is very low quality habitat that, on its own, would not be able to support a population. However, if the excess of individuals produced in the source frequently moves to the sink, the sink population can persist indefinitely.

Question 16

What is Leibig’s law of the minimum?

Answer 16

Growth is dictated not by total resources available, but by the scarcest resource (limiting factor)

Question 17

What is an optimal foraging or migration model?

Answer 17

Method of obtaining food or migrating that maximizes the benefit for energy/time expendature

Question 18

What are the costs and benefits of social groups?

Answer 18

Benefits: foraging efficiency, reduced predation, access to mates, help from kin

Costs: competition for food, increased disease transmission, attracting predators

Question 19

How does behavioral ecology fit into natural selection?

Answer 19

Survival and fitness depends on behaviors

Question 20

Shelford’s Law of Tolerance

Answer 20

geographical distribution of a species is controlled by the environmental factor for which the organism has the narrowest range of tolerance.

Question 21

What kind of experiments help discern a species range?

Answer 21

Transplant

Question 22

What two forms do competition take?

Answer 22

Direct/Indirect or Resource/Interference

Direct if trying to use a common resource in short supply
Indirect if one organism seeking a resource is harmed by another in the process, even if not in short supply.

Question 23

What are the major abiotic limitations to the distribution of plants and animals on land?

Answer 23

Temperature and moisture

Question 24

What is Rapoport’s Rule?

Answer 24

Polar species tend to have larger ranges

Question 25

What is generally true of the relationship between distribution and abundance?

Answer 25

They are positively correlated - widespread species also tend to be more abundant. Hanski’s rule.

Question 26

When modeling populations, its important to distinguish between ______ and _______ fertility/longevity

Answer 26

realized and potential.

Question 27

What is the competitive exclusion principle?

Answer 27

complete competitors cannot coexist

Question 28

What is a functional response?

Answer 28

The change in predator consumption in relation to the density of prey species

Question 29

What is a limiting factor in population regulation? What is a regulating factor in population regulation?

Answer 29

If a change in the factor produces a change in average or equilibrium density. E.g. a disease is a limiting factor in deer if more deer are present when disease is absent

If the percentage mortality caused by the factor increases with population density. E.g. disease is a regulating factor if it causes a higher fraction of losses as deer density increases

Question 30

What is the allee effect?

Answer 30

small populations can suffer reduced population growth> produces instabilities that can lead to local extinctions.

mechanisms: not enough mates

Question 31

Losses due to harvesting of an organism must be compensated by three things…

Answer 31

increased growth, increased reproduction, decreased natural mortality

Question 32

What do yield models assume and when does this break down?

Answer 32

Equilibrium, they fail when there are changes in conditions, weather, predators, disease, etc.

Question 33

What are three stochastic forms of variation that contribute to extinction risk?

Answer 33

demographic, genetic, environmental

Question 34

What effects does reduced connectivity have on population dynamics?

Answer 34

Affects rates of dispersal and immigration

Question 35

What is the neutral theory of biodiversity? What are its assumptions?

Answer 35

The differences between members of an ecological community of trophically similar species are “neutral”, or irrelevant to their success. This implies that biodiversity arises at random, as each species follows a random walk.

: that species are ecologically equivalent
: communities are saturated with species and in equilibrium

Question 36

What is the gradient of diversity? What are some explanatory mechanisms?

Answer 36

The increase in species richness or biodiversity that occurs from the poles to the tropics.

A combination of energy/climate and area processes likely contribute to the latitudinal species gradient.

Question 37

What are six factors that affect biodiversity?

Answer 37

: evolutionary speed : rapid evolution of new spp
: productivity : richness limited by production partitioning among spp
: disturbance : moderate disturbance slows competitive exclusion
: geographic area : larger/more complex areas make more niches
: interspecific interactions : competition affects niche partitioning and predations slows competitive exclusion
: ambient energy : fewer species can tolerate unfavorable conditions

Question 38

What is another core community structure pattern?

Answer 38

That most communities have few common species and many rare ones.

Question 39

What is a keystone species

Answer 39

species that occupies a role of critical importance to a community

Question 40

What is a dominant species?

Answer 40

One that controls the occurrence of other species

Question 41

What is fishing down the food web?

Answer 41

Fisheries being depleted of apex predators so catches become increasingly dominated by lower trophic level species

Question 42

What is the difference between local and global stability?

Answer 42

Local refers to system returning after small disturbance, global refers to system returning after large disturbance.

Question 43

What is the green world hypothesis?

Answer 43

Hairston, Smith and Slobodkin argued that predators reduce the abundance of herbivores, allowing plants to flourish. The green world hypothesis is credited with bringing attention to the role of top-down forces (e.g. predation) and indirect effects in shaping ecological communities.

Question 44

What is a trophic cascade?

Answer 44

Impacts flow down the food chain as a series of positive and negative impacts on successive trophic levels

Question 45

What is island biogeography theory?

Answer 45

Predict species richness based on island size (area) and isolation (distance). This theory does not try to predict species composition or abundance. It also considers species richness to be in dynamic equilibrium between immigration and extinction. Extinction and colonization rates are affected by island size and distance. Larger islands have more species and closer islands have more species. Species richness depends on size and distance. The theory also explains that more species means lower colonization rates and higher extinction rates.

Question 46

What is an example of a system with multiple stable states?

Answer 46

Coral reefs in the Caribbean can phase shift to algal dominance, both are stable.

Question 47

What is the species-area curve?

Answer 47

Shows the relationship between species and area, often used to refer to biodiversity increase with island size.

Question 48

What is the primary limiting factor on productivity in marine environments?

Answer 48

Nutrients, nitrogen then phosphorous.

Question 49

What is the metabolic theory of ecology?

Answer 49

Posits that the metabolic rate of organisms is the fundamental biological rate that governs most observed patterns in ecology. In MTE, this relationship is considered to be the single constraint that defines biological processes at all levels of organization (from individual up to ecosystem level), and is a macroecological theory that aims to be universal in scope and application.

Question 50

What does metabolic rate scale to the power of? What is this called?

Answer 50

3/4, a power law

Question 51

What are the implications of MTE on population growth?

Answer 51

The optimal population growth rate for a species is therefore thought to be determined by the allometric constraints outlined by the MTE, rather than strictly as a life history trait that is selected for based on environmental conditions.

Question 52

What are the implications of MTE on ecosystems?

Answer 52

The average production to biomass ratio of organisms is higher in small organisms than large ones. This relationship is further regulated by temperature, and the rate of production increases with temperature. As production consistently scales with body mass, MTE provides a framework to assess the relative importance of organismal size, temperature, functional traits, soil and climate on variation in rates of production within and across ecosystems.

Question 53

What are ecosystem services of coral reefs?

Answer 53

coastal protection, fisheries nurseries, aesthetic beauty

Question 54

What are weak effects?

Answer 54

When an interaction is not critical to the survival or fitness of another species, but they do interact.

More technical: When the removal or addition of a species
failed to cause a statistically discernible mean change in the abundance of a target species

Communities are structured by primarily weak interactions and some strong ones but weak effects, counterintuitively play a critical role in maintaining food web structure to their role in stabilizing.

Question 55

Describe what would you might believe would happen to species interactions (interaction strengths) if nutrients and light weren’t limited in an environment and the temperature increased. In and out of an equilibrium?
What happens to the carrying capacity in each situation

Answer 55

.

Question 56

Are positive interaction predictable features of natural communities?

Answer 56

We expect to see more positive species interactions in high stress environments that have higher consumer pressures, and less where the physical environment is benign and consumer pressure is less.

There are probably many exceptions to this.