BIOL1997 Flashcards
Module 5 (217 cards)
1
Q
What are coping mechanisms to deal with the environment?
A
o Morphology
o Physiology
o Behaviour
2
Q
What is behaviour?
A
part of how organisms respond to the biotic and abiotic environment
3
Q
What does behaviour affect?
A
Fitness
4
Q
What is fitness?
A
An individual’s relative contribution to the next generation’s gene pool
5
Q
What is the experiment involving the small heath butterfly?
A
Experiment
• Provide food of different quality for butterfly larvae to feed on
o Fertiliser levels either low or high- unenhanced and enhanced nutrition grass
• Larvae can feed on either grass
• When they become adults, given different foods
o Low in amino acids or high with amino acids
• Larvae that were fed with highest quality food had the highest fitness
o Variables looked at for this conclusion were egg quantity and hatching mass
o However, not much difference between butterfly that were fed high quality and low quality food
6
Q
Why is behaviour ecologically significant?
A
Is a link between individuals and their environment
Affect demographics (population levels outcomes)
Affects interactions among species (community-level outcomes)
7
Q
Why is behaviour evolutionarily significant?
A
Has some genetic basis
Affects fitness
Can be selected
8
Q
How do lizards behave to cool themselves down in the desert? What is their interaction with the abiotic environment.
A
o E.g. lizard cooling feet on hot Namib desert sand to avoid overheating
Rhythmically lift up and put down its feet to maintain cool
Feet never stays on same for more than a few seconds
9
Q
How do ant lions interact with biotic environments (ambush)?
A
o Ant lions ambush
Buried with pincers below the sand surface
If ants walk by, will unbury itself and catch the ant
Cook prey before they eat it by putting it on sand surface
10
Q
What are the properties of active predators such as dingos?
A
• Active predators- Agile, fast
o Probability of prey encounter is increased by chasing it
11
Q
What are foraging strategies defined by?
A
- What they eat: frugivore, herbivore, nectivore, granivore, gramnivore, insectivore, carnivore, omnivore
- How they get it: ambush vs active
- Diet breadth: specialist (one kind of food) vs generalist (variety of foods)
12
Q
What are common features of all foraging strategies?
A
- Non-random, that is, individuals make foraging choices
- Make choices about what to eat
- Optimal foraging theory- Macarthur, Piancka , Krebs
- Marginal value theorem- Charnov
13
Q
What is the optimal foraging theory?
A
o Modelled which food items to eat in a non-depleting environment
o Predicts foragers should maximize net rate of food intake
14
Q
What is the marginal value theorem?
A
o Modelled when to leave a food patch in a depleting environment
o Predicts that foragers should leave food patches when capture/harvest rate at patch is smaller than average capture/harvest rate
15
Q
What are criticisms of the commonly known foraging strategies?
A
o Foraging will occur at cost of energy if a particular nutrient is needed
o Animals that are hungry vs animals that are not hungry would forage differently
16
Q
What is the net rate model?
A
foraging maximizes net rate of energy delivered (energy gain per unit time)
17
Q
What is the efficiency model?
A
maximize energy gain per unit energy spent
18
Q
To discriminate against the net rate and efficiency model what experiment was done with bees and what was concluded?
A
• Tested with individually marked worker bees and artificial flowers
• Hence, found that efficiency model was upheld
• Conclusion:
o Forage non-randomly
o Maximize a foraging variable
19
Q
What are predictions of the optimal foraging theory?
Try to draw the graph
A
• Focuses on efficiency of energy gain
• But most foragers are also prey
• Should expect
o Foraging strategies to be linked to predator avoidance strategies
o Trade-off between nutrient value of food and predator hunting grounds
o All prefer the lowest cost patch
20
Q
How can organisms avoid being food?
A
• Run-away • Group together – more chance of bluffing it out or repelling predator • Hide (stick insect crypsis) Act costly • Act dangerous, mimic toxic organisms Be costly • Be toxic, have spines Feed in safe places or times • Vegetation cover
21
Q
How do red-bellied pademelons avoid being eaten?
A
- Red-bellied pademelons more likely close to shelter
* Probability of pademelons being spotted are less likely the further away from cover they are
22
Q
What are costs of anti-predator strategies?
A
- Feeding near vegetation cover may miss opportunities to forage elsewhere
- Grouping would result in competition for food and social aggression
23
Q
What do you need for anti-predator strategies to evolve?
A
Benefits>costs
24
Q
Using the barnacle geese as an example, what are the benefits/costs of being in a large group?
A
Competition for food –> less grass to eat
More birds present –> more eyes to look for predators
Less chance of being eaten in group due to dilution factor
25
What do courtships and mating behaviours involve?
```
o Male-male competition
o Female choice
o Results in non-random mating and non-random offspring
o Sexual selection
Put forward by Darwin
```
26
What are the costs and benefits of the Peacock mating behaviour?
o Peacock tail heavy and impractical but needed for courting
o High costs of a tail
Energy in production and maintenance
Risk of predation
o Benefits:
Access to mates and females
o Peacock tail arises from natural selection, via selective pressure associated with sexual reproduction
o Tail can be affected by predators and parasites- marker for male fitness so an intact tail is important
27
What is intrasexual selection?
Competition between males
Sexual dimorphism between males and females
• Females are smaller than male
28
What is intersexual selection?
Mate choice (females often choose the males)
Sexual dimorphism
• Females are plain but males are flashy
29
What is sperm competition?
Females mates with a lot of males
| When fertilization takes place, female will use fittest sperm to fertilize
30
What are the benefits and costs of parental care? Provide an example for benefits.
• Benefits: survival and growth of offspring
• Costs: missed opportunities to reproduce again
• In some species, offspring stay and help parents rear more offspring
• Example: superb fairy wren- 19 year study
o Offspring help parents rear more offspring
Collect more food for the next generation
o Increase of independent young with more helpers
31
Can beings without a central brain behave?
* Slime molds behave and aggregate together even though they don’t have a central brain
* While foraging they have to be aware of the risks such as being in the light or being in dry conditions
32
How do plants behave?
```
• Leaves and stems
o Grow towards light
o Respond to their environment by moving
• Roots
o Grow along chemical gradients towards nutrients
o Respond to their environment by moving
• Plants behave but
o In a different time frame
o A different way of moving
```
33
What is a group and what are properties of a group?
o Multiple organisms occupying a common space
o Can be ephemeral or consistent
Ephemeral- last for a very short time
o Can be social (positive or negative), indirect (sharing common resource) or accidental (random chance)
-Not structured
34
What is a population and what are properties of populations?
o A number of organisms of the same species in a define geographical area
o Properties of populations include:
Number of individuals or population size
Area they occupy
Age structure
Sex ratio
35
What is the composition and structure of a population influenced by?
life history, mobility and habitat
36
What are populations essential in the study of?
```
Ecology
• Distribution and abundance of individuals
• Density
Evolution
• Populations of organisms evolve, not individuals
• Gene flow
Conservation and management
• Invasive species
• Defining threat status of taxa
• Translocations and restoration
```
37
A population must be:
Cohesive
Aggregate
Structure
38
What is a unitary individual?
o Develop from zygote: genetically distinct
o Form is determinate
o Development and growth predictable
39
What is a modular individual?
o Grow by addition of modules (runners) and are genetically identical
o Individuals are highly variable in the number of modules
o Modular individuals often hard to count and define
40
What do populations have in terms of dynamic and distribution?
o Temporal dynamics
Lynx populations always peak after that of snowshoe hare
o Spatial distribution
-Affected by natural selection
41
How do you calculate population growth rate?
o Populations change in numbers over time
o Change can be positive or negative
o Rate(r) = change/unit time
o Geometric increase in growth represented by exponential growth
42
Do populations grow at the same rate?
No- at a different rate
43
What are the variables that drive changes in population size?
```
Birth
Death
Emigration (number leaving population)
Immigration (number entering population)
Growth (individual)
Age at maturity
Sex ratio
```
44
What is the population growth rate?
The change in numbers of individuals over time
45
What determines growth rates?
Addition and loss balance
46
When is a population closed?
When there is no emigration or immigration
47
Geometrically, how do you predict the number of individuals in the population at time t+1 when it is a closed population?
o Nt+1= Nt + Births-Deaths
48
What is discrete reproduction? Draw the graph and describe
o Discrete- reproduction occurs periodically (seasonally)
| Results in pulses- pulse of individuals that have entered population, population decreases, another pulse occurs
49
What is continuous reproduction? Draw the graph and describe
o Continuous- reproduction occurs year-round
| Smooth curve with no seasonality effect
50
How are birth rates estimated?
```
o Histology of reproductive organs
o Capture/counting of fertilized gametes
o Counting of newly born individuals
Eggs, fruits…
Marsupials- number of young developing in pouch
```
51
When does growth stop?
At carrying capacity
52
Is population growth limited? How?
Yes, it is limited by resources
53
How do you estimate death rates?
o Tagging
Following individuals (for sessile organisms)
Probability based ( for more motile organisms)
o Changes in size structure
Look at frequency vs age curve to look at mortality age
Estimate death rate from that
o Very challenging
54
Geometrically, how do you predict the number of individuals in the population at time t+1 when it is an open population?
• Nt+1= Nt + Births-Deaths + immigrants- emigrants
55
When is a population open?
If individuals immigrate and emmigrate
56
How do you estimate demographic rates in open populations?
o Tagging and recapture
Physical
GPS
Radio telemetry
Acoustic
o Genetics
Genetic similarity occurs with only very low levels of interbreeding between populations
Genetic differences- no movement between populations
Genetic analysis of microsatellites
Genetics measures the spatial and temporal aspect of different species
57
What are metapopulations and how are they formed? What do they depend on? Describe an example.
o Local populations, but individuals move
o Local populations in a big population
o Demographic rates vary spatially
o Large-scales dynamics dependent on local demographics and connectivity
```
• Mayfly
o Larval stages mature in local pools
o Adults disperse between pools
o Mortality variable from pool to pool
o Some pools are sources (low mortality) while others are sinks (high mortality)
```
58
How do you estimate population size?
- Counts
| - Mark-release-recapture
59
What are different types of counts?
o Visual
o Auditory
o Acoustic
60
Why is the mark-release recapture method done?
o The MRR method estimates the total population size from a sample proportion of a mobile species
61
What is the mark-release-recapture method?
Take a sample of organisms
Mark them
Release them into population
Sometime later, recapture samples
62
What are the assumptions of the mark-release-recapture method?
Close population (that is, no immigration, not emigrations)
All individuals are equally likely to be marked
Marked individuals do not lose their mark
Marked individuals move back into the population randomly
63
What is the mark-release-recapture formula?
```
o Formula- M/N= R/n
N= population size
M= marked 1st time
R=recaps (marked)
n= sampled second time
```
64
How do you estimate growth and age in
- Trees
- Perennial plants
- Mammals
- Fish
o Trees-tree rings
o Perennial plants- rings in tap root
o Mammals- cementum rings in teeth
o Fish-otoliths
65
What do age and size structured population dynamics affect?
Fecundity
Survival
Population growth
66
What do life tables show?
o Life tables: show survivorship probability at each age
| Long term studies- key to understanding population dynamics
67
Can all members of a population be treated as identicals?
o Cannot treat all members of a population as identical as unrepresentative of natural population structure
68
Why is there growth rates in western countries?
o Changes in human population size-mostly due to behavioural changes
o Current trend in developed countries- ageing population
o Growth rate of many western countries
Below replacement rate-falling death rates
So population numbers will level out then fall
69
What can contribute to extinction events?
```
o Genetic stochasticity (small populations)
o Demographic stochasticity ( random nature of births and deaths)
o Environmental stochasticity (variability)
o Catastrophes (cyclones, epidemics, fire)
o Human impacts (habitat loss, fragmentation, over-exploitation, hunting, pollution, introduction of new pest species, other environmental changes)
```
70
What is population viability analysis and why is it useful?
Tool to model population dynamics over time
• Uses basic population data
• Includes environmental variation in these values
• Can change values to reflect human impact
-Finds minimum viable population size
71
What information is needed for population viability analysis (PVA)?
* Carrying capacity
* Annual variation
* Maximum age
* Adult and juvenile mortality
* Mean litter size
* Chance of predator arrival
72
How can robustness of conclusions be tested?
• Test the robustness of conclusions using sensitivity analysis of the parameters based on known or hypothesized variance in the data used to estimate the parameters
73
What is a species?
• A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring
74
What is the biological species concept?
o Mayr’s definition of a species
Groups of actually or potentially interbreeding natural populations, which are reproductively isolated from other such groups
Can breed one variety with another
75
What are limitations of the biological species concept?
o This concept may not be relevant to organisms that are capable of asexual reproduction
o If the definition of a species requires that two individuals are capable of interbreeding, then an organism that does not interbreed is outside of that definition
o Does not apply to: as interbreeding cannot be observed
Fossils
Clonal species
Asexual species
o Organisms may also breed beyond the notional definition of species
Interspecific hybrids
• Fertility depends on which way the cross is going (what species the male and female are)
o Such as lomatia hybrids that have a lot of intermediate forms in overall size of the plants, partial amounts of divided leaf, stem…
Ring species
76
What is a ring species?
• A ring species arises when a parental population expands around an area of unsuitable habitat in such a way that when the two fronts meet they behave as distinct species while still being connected through a series of intergrading populations
• Geography can change when the species can breed and when they can’t
-ensatina high vs low elevations can't breed
77
What are other species concepts?
```
o Ecological species
How do they live, where do they live
Classified by geography
o Biological/Isolation species
o Genetic species
Cryptic species defined by their genotype
o Cohesion species
o Evolutionarily significant unit (ESU)
o Phenetic species
Classified through phenotype
o Microspecies
o Recognition species
o Mate-recognition species
```
78
How does hybridization occur?
• Breakdown of reproductive isolating barriers which usually prevent gene flow between closely related species
• Potential causes include
o Habitat disturbance (species in closer proximity)
o Secondary contact (increased migration distances- pollinator change or dispersal)
o Altered phenology (leading to overlap in flowering times and pollen transfer)
o Altered genetics (not proven for Lomatia species)
79
What are the potential evolutionary outcomes of hybridization?
o Sterile first generation
o Speciation
o Enhanced variation
80
Why do we have a species problem?
• Because:
o Differing measures are often used, such as similarity of DNA, morphology and ecological niche
o Presence of specific locally adapted traits may further subdivide species into “infraspecific taxa” such as subspecies
o Many organisms do not conform to the reproductively isolated criteria
o Not possible to test this for fossil taxa
81
What is the species problem?
The difficulty of defining species
82
In different domains of study, what under-species classifications are used?
• Groups within a species can be defined as being of a taxon hierarchically lower than a species
• In zoology only the subspecies is used
• In botany, the variety, subvariety and form are used
• In conservation biology, the concept of evolutionary significant units is used, which may be define either species or smaller distinct population segments
• In horticulture there are cultivares
o Same species but slightly different genetics
• There are also breeds of domesticated animals such as dogs
• Variation between males and females
83
What are estimates of the number of species on Earth?
1.8 to 160 million
84
What is the range of the current species count?
1.5-1.8 million
85
How many named and unnamed species are there in Australia?
19200 named species
| 420000 unnamed species
86
Is the number of possible/named species accurate?
No- sources say different things
87
What is biological diversity?
* Biological diversity is the variety of life on earth
| * Number, relative abundance and genetic diversity of organisms on earth
88
What are the components of biodiversity?
o Genetic diversity
o Species diversity
o Community diversity
o Landscape diversity
89
What is species richness?
Number of species
90
What is species turnover?
Difference between samples from different plots
91
What is evenness?
equitability of individual abundance among species
92
To encounter rare species, how many samples need to be collected?
Many
93
What does species composition respond to?
Environmental conditions
94
What are rank abundance curves used for and how are they interpreted?
• Rank abundance curves can be used to compare community composition
o For more diverse, rank more shallow (on the right)
o For not diverse, rank is deep (on the left)- abundance are more even
95
What are the 3 types of community diversity?
* Alpha diversity is the number of species within a chosen area or community (local diversity) (species richness)
* Beta diversity is the difference in species between areas or communities (species turnover)
* Gamma diversity is the diversity of a landscape or all areas combined (regional diversity)
96
What is a community?
• Communities- two or usually more species that occur together in space and time
o In addition to co-occurring, community members interact with each other as an ecological unit
o Combination of all the organisms that interact at a particular place at a particular time
97
What is quantified with diversity indices?
• Diversity within communities, alpha diversity is quantified with diversity indices
98
What do species diversity indices do?
• Combines number of species and relative abundance of individuals within species
99
What are two different types of commonly used indices?
o Simpson’s index
Emphasises common species
o Shannon-Weiner index
Emphasises rare species
100
What is the formula for the simpson diversity index?
= 1 - Ʃ 𝑛(𝑛-1)/N(N-1)
where 𝑛 is the number of individuals displaying one trait (e.g. the number of individuals of one species)
𝑁 = the total number of all individuals
101
What is the formula for the Shannon-Weiner index?
```
H = -SUM[(pi) * ln(pi)]
E=H/Hmax
Where,
SUM = Summation
pi= Number of individuals of species i/total number of samples(N)
S = Number of species or species richness
Hmax = Maximum diversity possible
E= Eveness=H/Hmax
```
102
When are index values high?
• Index values are high if there are many species or if evenness(equitability) is high
103
What are other ways to describe or quantify species diversity?
• There are many ways to describe and quantify species diversity. Common approaches include species richness, species turnover (beta diversity), rank abundance curves and species indices
104
Describe where autotrophs get their energy, where they are in the food chain and examples of them
Producers
Synthesize organic from inorganic compounds
-Gets energy from the sun through photosynthesis
E.g. green plants , phytoplankton, algae, chemosynthetic bacteria (that reduce dioxide to organic carbon and gain energy from reducing inorganic substrates)
99.9% energy from the sun, otherwise from 0.1% deep sea vents
Bottom of food chains and food webs
105
Describe where heterotrophs get their energy, where they are in the food chain and examples of them
Consumers, degraders, decomposers
Depend on autotrophs and other heterotrophs as sources of foods
Animals
At the top of the food web
106
What are different trophic levels?
* Autotrophs
* Primary consumers
* Secondary consumers
* Tertiary consumers
107
Do trophic levels have to follow in succession?
No, but autotrophs are always at the base of the food chain
108
What is a top down forcer?
• Top down forcer- suppress activity of numbers of the trophic level below them
o Depress the trophic level on which they feed, and this indirectly increases the next lower trophic
109
What is bottom up control?
• Bottom up control
| o Increased production results in greater productivity at all trophic levels
110
What are food chains balanced by?
• Most of the time, food chain balanced by top down and bottom up systems
111
How does energy and inorganic carbon flow in ecosystems?
• Energy flows throughout an ecosystem up trophic levels
o Transfer of energy from lower levels to high level consumers
• There is a loss of energy as you move between levels (only 10% of energy moves from levels above, 90% is lost as metabolic heats and is lost)
• As levels go up, initial energy largely decreases
• Transfer of inorganic material in the ecosystem
112
Why don't food chains have many levels?
Hypothesis-
1. The energy hypothesis (Elton)
2. The dynamic stability/constraint hypohesis
113
What is the energy hypothesis?
Insufficient energy coming in
Run out of energy before long chains can be formed
Energy loss between trophic levels
Hence, high productivity ecosystems should have longer chains
114
What is evidence for the energy hypothesis?
o Tree hollow (leaf litter Microbes Mosquito larvae Chironomid larvae (carnivorus))
o Experiment-
Leaf litters manipulated to alter productivity (large, medium, small)
15 replicates per level
48-week trial
• Went in at different number of times to count species…
Quantified number of species, number of trophic links, maximum food chain length
Stats analysis- ANOVA, Model DV
o Results supported the energy hypothesis
115
What does the dynamic stability/constraint hypothesis postulate?
Longer food chains less stable because
• Fluctuations at low trophic levels magnify at high trophic levels
• Small disturbances are magnified at top levels
• Top predators more likely to go extinct
Predicts stable environments should have longer chains
116
What is evidence for the dynamic stability/constraint hypothesis?
Experimental evidence:
• Tree hollows experiment (same as energy one)
• Week 24- stopped raining but microbes and mosquito larvae need water (external disturbance)
• Following this disturbance, there was a bigger drop in the long (large leaf litter) food chain tree hollows than the medium and low ones.
• Supports hypothesis
117
Are observations between ecosystems useful in determining why food chain length is so short?
No
o Observations among ecosystems useful but may confound factors
Not just differences in productivity
Producers have very different life forms
E.g comparing tropical to grassland for trophic links would be bad
118
Are the energy hypothesis and dynamic hypothesis mutually exclusive?
No
119
Along which gradient is there species loss?
• There is also species loss along the latitudinal gradient- if you move from the tropics to north/south poles, there is a species loss
120
What are different kinds of interactions amongst species?
o Mutualism: 2 organisms in close association, both benefit [+,+]
Can include obligatory mutualism or facultative (not necessary but still beneficial)
o Competition: [-,-]
Mutual depreciation of evolutionary fitness
o Predation: e.g. herbivory, carnivory, parasitism [+,-]
o Commensalism: [+,0]
One organism benefits, the other one doesn’t care
o Amensalism [0,-]
When we walk on ants
o No interaction [0,0]
121
Why is herbivory important?
o Herbivory is the biggest interaction on the planet
o Important for individuals
o Can affect populations and communities
o Can affect ecosystem processes
122
What is an experiment that was made on the effects of lead selection on population dynamics of an insect herbivore?
o Eat plant material digest convert to insect material insect performance and survival population growth
Experiment-
• Plants: aspen, birch, maple
• Herbivore: tussock moth
• Environment: high and low carbon dioxide, high and low light
• Tussock moth larval survival depends on growth conditions of the plants
o Aspen: best under high carbon dioxide + low light, worst under high carbon dioxide + high light, survival on aspen changes: 80% 20%
• Population dynamics change
123
What are the community effects of herbivory?
o Some herbivores can affect number of plant material for other herbivores, which can affect the consumers preying on those herbivores, hence making a ripple effect in the whole community
• Preferences for some plants increases abundance of not preferred plants
124
Is herbivory good for plants?
No
o Tissue loss by herbivores= Annual allocation to reproduction in plants
Lose tissue that could have been allocated to reproduction, so lose fitness by being chewed on
o Herbivores eat the high quality plant tissue
o Plants have defenses against herbivores (herbivores exert selective pressure)
125
What is an assemblage?
a group of species that live together with no assumptions made about how or whether they interact with each other
126
What are ecotones and what can they be?
• Ecotones-a region of transition between two biological communities
o Gradual transitions the norm rather than abrupt hard edges
o Demarkation line- can be broad and soft, or hard
127
How do communities change over time?
o Local colonisations and extinctions
o Classic models driven by succession
o Predictable patterns of change in response to a disturbance
o New communities are being assembled by human activity
o New communities often homogeneous in many parts of the world
128
What is biotic homogenization?
Biotic homogenization- fauna and flora around the world end up being the same due to transport by human activity
129
What are different types of succession?
```
o Primary succession
Bare area without soil- everything starts from 0
Can be driven by human activity
o Secondary succession
In a habitat modified by other species
• When there are later arriving species
```
130
What are the 3 models of succession?
```
o Facilitation
Early arriving species make environment more favourable for later species
• Fixing the soil
• Increase moisture level
• Might fix nitrogen…
```
o Tolerance
Neither negative nor positive interactions between early and late species
Not well supported- as no interactions= no communities
Would be more random then it is
o Inhibition
Early species inhibit later species
Only when early arrivals die that other new species can move
131
What are pioneer plant species and what do they do?
```
Get into disturbed areas quickly
Grow in sun
Fix nitrogen
Good dispersal
Small seeds
Rapid growth
Short generation time
Poor competitors
• Not a lot of energy yet after suiting themselves to the environment
E.g. weeds
```
132
What do climax plant species do during succession?
```
Shade tolerant
Slow growth
Long-lived
Good competitors
• Can allocate more energy to competing with other species
The final community in a successional series
Self-perpetuating, no replacement
Keep getting reset by disturbances-
• Natural
• Anthropogenic
```
133
How does competition for limited resources occur?
• One organism deprives another organism of resource through:
o Exploitation
Better at exploiting resources, using them more efficiently and quickly than other organism
o Interference
Direct fighting between individuals
• Plants can produce chemicals to inhibit growth of another `
134
What is intraspecific competition?
Intraspecific competition
• Within species
• Density dependence
• Population regulation
135
What is interspecific competition?
• Between species
• Competitive exclusion
• Niche differentiation
o Evolve differences in resources them
136
Why are barnacles often studied for competition?
o Barnacles- studied a lot for competition because they are so many
137
What was Connell's barnacle experiment? What conclusions did he get from it?
Not overlap between two species
• Competition or different species preference?
• Transplantation experiments (switch both populations)
• Remove one species and see if the other moves in
Chthalamus- top of rocky shore
Balanus- bottom of rocky shore
Chthalamus- able to extend its range down in the absence of Balanus: therefore mortality not caused by submergence but by interspecific competition
Balanus not affected by presence/absence of Chthalamus
Balanus distribution affected by intraspecific competition
Direct observations showed that Balanus competes directly by smothering, undercutting or crushing
138
Is disturbance important for succession?
Yes
139
What kind of disturbance is the best for high diversity?
• Intermediate disturbance
o Patchy mosaic of disturbance creates highest diversity --> intermediate disturbance hypothesis
o Connell- observations of storms on tropical rainforests and coral reefs
140
What does resilience mean?
the time it takes for a community to come back, on the assumption that they can
141
What are problems with restoration criteria?
• How long before a community returns to an equilibrium after disturbance? Are there equilibria?
• What objective and non-arbitrary criteria for determining pre- and post-disturbance conditions do we have?
• Australia often uses the ‘before 1788’ criterion to define pre-disturbance conditions. But there are problems with this:
o Not sure what 1788 looked like
o Australia had been occupied beforehand
142
What is an ecosystem?
The community of living organisms considered in conjuction with the abiotic components of their environment, interacting as a system
o Living and non-living
o Looked at by productivity
Tropical forests- most productive, oceans- least productive
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How is ecosystem productivity controlled?
o Ecosystem productivity is controlled by efficiency of recycling as well as by energy available
144
What is a global ecosystem cycle?
materials transported in the atmosphere all over the world (water, carbon, nitrogen, Sulphur)
145
What is a local ecosystem cycle?
o Local ecosystem cycles --> Phosphorus, potassium, calcium, and magnesium move through soil
146
Can productivity in ecosystems change through time?
Yes
147
What is the difference between young and old ecosystems?
o Young ecosystems have more actively growing tissue, but older systems have more biomass
148
When can regeneration of the original ecosystem be impossible
If resources are limited
149
What can upwelling of the ocean do to its ecosystem?
o Marine systems relatively unproductive
o Nutrients (especially nitrogen and phosphorus) tend to accumulate at great depths and are unavailable to phytoplankton
o But with action of strong offshore winds, nutrients can be brought up from the depths
o Major fishing grounds in upwelling zones where nutrients are forced up
Brings bigger predators
150
Describe the water cycle
o 97% of water on earth is in the oceans
o Global cycle
o Water will evaporate --> get to atmosphere --> cools down --> falls on distal land or oceans
o Processes of convection, precipitation, transpiration and respiration move water around the cycle
151
Where is water stored in the water cycle?
o 3% of total water is relatively inaccessible, in icecaps, glaciers and deep groundwater
152
What is the water cycle in Australia, and what must be done by consumers as a result?
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2/3 mainland Australia is desert
Rainfall highly variable
Desert ecosystems productive in pulses when rain falls, or from utilization of reserves (seeds, lignotubers) at other times
Consumers must:
• Adopt a pulse and reserve pattern
• Eat reserves of other organisms
• Adopt opportunistic feeding habits
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153
Describe the carbon cycle
o Local ecosystem cycle
o Most carbon is locked up in earth’s rocks as carbonate (and also fossil fuels)
o The most active pool is carbon dioxide, 0.04% of the atmosphere
o Carbon dioxide is withdrawn by photosynthesis and replaced during respiration
o Large amounts of carbon dioxide are dissolved in the ocean
o Burning of fossil fuels returns carbon dioxide to the atmosphere faster than it can be cycled
This contributes to global warming
154
Describe the nitrogen cycle
o Global cycle
o Abundant in atmosphere, 78%
o Plants cannot absorb atmospheric nitrogen
o Absorbed as ammonium or nitrate after fixation of nitrogen by symbiotic bacteria, or in soil solution
o Denitrifying bacteria convert nitrate back to gaseous nitrogen
o Electrical storms also fix nitrogen
o Nitrogen becomes limiting if microbial activity is inhibited
155
Describe the rural dieback effect
o Tree dieback results from long or repeated periods of sublethal stress
o Effects of increased stocking rates, growing exotic pasture species, adding fertilisers and land-clearing combine to cause rural dieback
o Insect damage to leaves is worse where the soil fertility is high
o Stock congregate under few remaining shade trees, both damaging saplings and enriching the soil
156
Describe the phosphorus cycle
o Local cycle
o Esseential to all life, in ATP
o Not common in Earth’s crust or in atmosphere
o Taken up by plants as phosphate from sparingly soluble soil storage pool
o Australian flora are well adapted to low P, and efficient at recycling phosphorus
o Symbiosis between plant roots and mycorrhizal fungi enhances the phosphorus supply
157
What is the effect of sea otters on the carbon cycle?
o Eat sea urchins, which eat kelps
o Sea otter keeps kelp populations up
o Kelps provide habitat and food for fish, which are food for bigger fish
o Sea otters help indirectly increase carbon dioxide sequestration through regulation of sea urchins
o Kelp increases diversity of fish and birds
158
What is the anthropocene?
The current era
159
What is the anthropocene characterised by?
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o Show there is a big change in species composition and strata geologically
o Mass extinction going on
o Might see a thin stream of plastic and concrete in strata
o Characterized by climate shift
o Habitat fragmentation
o Pollution globally
Air pollution in big cities
Contaminants
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160
What are the different aspects of the human footprint?
- Pollution
- Oil
- Habitat loss and fragmentation
- Climate change
161
What are examples of toxic inputs that we put in the environment?
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Pesticides
Manufacturing
Industrial accidents
Chemical spills
Atmospheric pollution
Plastics
Nanoparticles
• Plastic breakdowns
• Put into common products
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162
What is the effect of toxic inputs?
-Effects very pertinent in predators at top of the food chain
• Effects particularly apparent in raptors (birds of prey), although people and other organisms were also affected
o Chemicals consumed, taken up in tissues, and building up via bioaccumulation
o E.g. the bald eagles
Stopped calcium metabolism crucial for eggshell production
• Reproduction was curtailed
• When these pesticides were banned many populations recovered
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What is bioaccumulation?
Occurs when an organism absorbs a toxic substance at a rate greater than that at which the substance is lost accumulation
Persistent and mobile
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In what tissues does bioaccumulation often occur?
Fat and liver
165
In which trophic level does bioaccumulation occur the most and why?
Particularly in higher predators at the top of food chains and webs
• Predators eat prey with the toxins in their tissues
• Don’t initially see effects of toxin quickly
166
What are PCBs?
o Chlorinated organic compounds used as insulation in electrical equipment
167
What was the surprising finding of PCB levels?
PCBs found in the breast milk of mothers in southern Quebec in the mid 1980s
Obtained milk from Inuit mothers as a control but found that inuit milk had 5 times the PCB levels
Another study found that more than 2/3 of children had unacceptably high levels of PCBs
Older people had higher levels
Children born to women who ate PCB-contaminated fish, narwhals and whales, in which they eat a lot of fats or other body parts where the PCB accumulates
168
When there is PCB in the womb, what is the effect on children?
```
• 11-year olds exposed to PCBs in womb had
o Lower IQ
o Poor memory
o Shortened attention span
o Learning difficulties
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169
How are PCBs carried from topics to other parts of the world?
Evaporate from soils, carried on winds (fractionation) and then condense out in the cold as toxic snow and rain (distillation)
Systematic transfer from warm to cold
• Very slow breakdown in cold climates
170
What are examples of heavy metals and what effect did it have on the california condor?
• Heavy metals (mercury, lead, cadmium)
o Carcinogenic
o California condor and lead poisoning
Condors ingest lead after feeding on the carcasses of animals that hunters have shot, leading to chronic lead poisoning
• Many have dangerous lead levels in their bodies
• Can damage nervous system and impair liver and kidney function
Lead bullets banned, but feather and blood samples from trapped birds found no discernible difference in lead levels before and after the ban
Intensive captive breeding and medical intervention- requires perpetual, intensive support
Modest recovery of the California condor now
171
What are types of human pollution?
Toxins
| Heavy metals
172
What is the problem with oil spills?
o Clean up attempts can be as damaging as the oil itself, with impacts recurring as long as clean-up continues
o Strong pervasive biological interactions in rocky intertidal and kelp forest communities contribute to cascades of delayed, indirect impacts and expands the scope of damages well beyond the initial direct losses and thereby also delays recovery
173
What is one of the major contributers to biodiversity loss?
Habitat loss
174
What are primary drivers of diversity?
o Fragment size and isolation are primary drivers of diversity
The more isolated, the less diverse it will be
Especially in terms of top predators
175
What happens to edge effects during habitat loss and fragmentation?
o Edge effects are prevalent
Microclimatic factors strongly affected on edges
• Wind
• Hydrology
Increase in woody vines near edges doesn’t compensate for loss of trees
176
What are effects of habitat fragmentation?
- Biomass collapse
| - Irreversible shifts (ecological meltdown)
177
What was done in the amazonian forest to model biomass collapse?
• Amazonian fragments
• Experimentally fragmented landscape made in the 1980s
• Patches of 1,10 and 100 ha isolated by clearing/burning to create pasture
• Control plots
• Found that:
o Rate of biomass loss greater near forest edges (small patches)
o Decline in above ground biomass before and after fragmentation
High tree mortality
No recruitment of new trees
• Results could be due to edge effects
178
What is an example of an ecological meltdown in Venezuala after dam construction?
• Construction of dam in Venezuela
o Formed islands
• Small and medium islands do not support 75% of vertebrates from mainland and control sites- mostly predators lost
• Remaining vertebrates are invert predators, seed predators or herbivores
o Tend to be hyper abundant
• Due to the fact that top predator numbers dwindled in islands due to lack of prey and space, herbivore numbers climbed
• This led to a decline in forest and plants
• Hence leading to a decline in herbivores as plant numbers dwindled
• Evidence of a trophic cascade unleashed in the absence of top-down regulation
179
What is climate change?
o Carbon dioxide dramatic increases over centuries heat trapped by greenhouse gas warmer environments
180
What are climate changes predicted and expected effects on ecology?
Animals and plants
• Range shifts (latitudinal or altitudinal)
• Abundance changes
• Change in growing season length
• Earlier flowering, emergence of insects, migration and egg-laying in birds
• Morphology shifts (e.g. body and egg sizes)
Hydrology and glaciers
• Glacier shrinkage
• Permafrost thawing
• Later freeze and earlier break up of river and lake ice
o Species favoring ice-dominated systems with shallow benthic communities will diminish, and be replaced by systems dominated by pelagic fish
• Loss of habitat for many species
• Opportunities for new fisheries
181
How many species are on the IUCN red list?
• IUCN red list has 20,000 species at risk of extinction
| o Now 25% of mammals, 41 % of amphibians
182
How much higher is the current rate of extinction than background rates?
• Rate of extinction 10-100000 times higher than background rates
o Should be only 1 species every few years
o 75% of taxa in multiple groups reach the 75% line, have a mass extinction on the hands
183
How many Australian species have been lost in the last 200 years?
• Australia has lost ~33 species in the last 200 years
184
What animals have suffered most?
• Non-flying mammals in the “Critical Weight Range” (CWR) have suffered most
o CWR 35g to 5.5 kg- arid zone species suffered most
o One forest species has become extinct (pipistrelle)
o Overall: >30% of nation’s mammals are extinct or threatened
185
What are the losses in Western NSW?
o Faunal losses
41% of marsupials
65% of rodents
• No native rodents
o Biggest regional loss of mammals in the world
o Droughts would be less terrible as these species have good effects on soil
o Numbat migrated, by 1980, from NSW to Western Australia
186
Who was the father of conservation biology?
Soule
187
What are the aims of conservation biology?
o To describe problems and understand processes
o To predict impacts of threats
o To develop solutions
o Ultimately: to stop more species/communities/ecological processes going extinct
188
What are the two different paradigms of conservation biology?
- Small population
| - Declining population
189
What is the small population paradigm?
The effect of small numbers on a population’s persistence
That is, stochastic influences (demographic and environmental, genetic drift, inbreeding depression)
How or why not an issue
190
What is the declining population paradigm and what are some examples?
Why the population has declined to low numbers, what might be causing it and how to reverse the decline
Diagnose the causes of declines and treat them
Have to be more concerned about them
Koala- big distribution but declining in Victoria (vulnerable)
Brushtail possums- inland population went extinct two years ago
191
What are Diamond's extinction forces?
Alien species
Overhunting
Habitat loss
Co-extinction
192
What are Wilson's extinction forces?
```
Habitat destruction
Invasive species
Pollution
Human over-Population
• The key difference that underpins everything else
Over-harvesting
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193
How many introduced species of vertebrates does Australia have?
56
194
What are the annual economic costs of alien species management in Australia?
o 800 million-1 billion managing pest animals
o 4 billion managing weeds (direct control and lost production)
New Zealand has more alien plant species than native ones
195
Who brought the new megafauna into Australia?
New invaders (europeans)
196
What does naturalised mean?
when native species have no recognition of alien species: they recognize them to be part of the predator fauna
197
How do alien species get into foreign countries?
Via delibarate introduction due to:
```
• Acclimatisation societies
o Ornamentals
o Agricultural
o Domestics
o Biological control
```
• Human traffic
o Trade routes
o Ease of global travel
o Poor quarantine
198
What is the tens rule?
o 1 in 10 of the plant and animals species brought into a region will escape to appear in the wild
o 1 in 10 of hose escaped species will become naturalized
o 1 in 10 of these will become invasive
199
What are the common characteristics of introduced invasive species?
* Maximize or enable high reproduction
* Enable great ecological dispersal
* Enable species to be greatly ecologically flexible
* Traits of pioneer species in succession
200
What is the impact of the fox on Australian fauna and flaura?
Competes with carnivorous marsupials
Preys on everything
Linked to 12 extinctions and a huge threat to mammals, birds, reptiles and amphibians
Native species aren’t aware of the red fox
Fox distributions limited by and facilitated by rabbit distribution
• Introduced in Victoria
Fox distributions suppressed by dingo over large areas
201
What is a strategy against introduced flora and fauna and how is it maintained?
Pest proof enclosures
• Very costly to maintain
• Pest mammals constantly try to reinvade the enclosure
o Looked at how many animals tried going in the artificial holes
202
Why does overhunting occur?
```
• Humans over-exploiting wildlife
• Historically was an enormous problem
• Because of:
o Potential competitors
Bounties paid on brush-tailed rock-wallabies in NSW: species is now endangered
o As food/resources
Shark for shark fin soup
o Overseas as bushmeat, wild meat
o Overexploitation risks higher in data-deficient systems
```
203
What is the major cause of species extinction?
Habitat loss
204
What does the island biogeographic theory suggest?
• Island biogeographic theory suggests that:
o Reducing habitat area to 10% of its former extent will eventually cause about 50% of species dependent on natural habitat to disappear
o Predictions not always matched by observations, but on average works
205
What is the concept of extinction debt?
• Extinction debt reflects the future ecological cost of current habitat destruction- extinctions occur generations after fragmentation due to reduced habitat area and edge effects
206
What is moderate habitat destruction predicted to do?
• Moderate habitat destruction is predicted to cause time-delayed but inevitable, deterministic extinctions
207
What is co-extinction and an example of this?
• Critical ecosystem functions lost when species are lost
• When one partner goes extinct, the other partner may go extinct to (specific prey-predator interactions)
• Passenger pigeon- once most numerous bird on planet: hunted to extinction in USA
• Specific louse (C.Extinctus and C.Defectus) which only inhabited passenger pigeon also became extinct
o But C.extinctus was rediscovered on the extant band-tailed pigeon
o C. Defectus may have been a case of misidentification of the existing lous, C.Flavus
208
What are engineer species?
o Provide organic material pits for plants
| o Maintain top soil
209
What are solutions for conservation?
- Experiments
- Modelling
- Legislation
- Smart ecological solutions
- Integrated pest management
- Restoration ecology
210
What are examples of an experiment that made a huge impact on conservation in western australia?
Examples- meta analyses
Fox control and native mammal conservation
Endangered black-footed rock-wallaby in WA wheatbelt- Kinnear
• 1080 poison baits for foxes
• The wallabies were protected
Western Shield Program- successful mammal conservation program
• Dumps 1080 by air to poison foxes twice a year to allow prey to recover
• Brought back from brink loads of native mammals
211
Why are experiments useful in conservation?
o Key to identifying processes driving extinction and allowing management of future predictions to be made
212
Why is modelling useful in conservation?
o Modelling population dynamics to predict impacts and identify management options
213
What listing does legislation need?
```
o Australia- federal listing
o Listing in NSW
Look at management plans
o List species, populations, communities
o Identify critical habitat
o List threatening process
Threat abatement plans
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214
What do smart ecological solutions do?
Adress causal factors rather than patterns
215
What does integrated pest management do?
o Interrelationships between pests means we can’t just control one or others will benefit
216
What is ecological restoration?
o Ecological restoration is the process of repairing damage caused by humans to the diversity and dynamics of indigenous ecosystems
o Restores ecosystems to some pre-impact or reference state (but what is reference state)
217
How can ecological restoration be done?
o Enhancing habitat quality
| o Restoring ecosystem functions via reintroductions
