Ecology and Evolution in the Anthropocene Flashcards
(85 cards)
1
Q
What is the difference between a realized and fundamental niche?
A
A fundamental niche is the full range of environmental conditions that a viable population of species can occupy and use when not constrained by limiting factors.
A realized niche is the range of environmental conditions that a viable population of species can occupy and use when constrained by limiting factors.
2
Q
How did Hutchinson (1957) define a niche?
A
A region (n-dimensional hypervolume) in a multi-dimensional space of environmental factors that affect a species.
3
Q
Hutchinson’s definition of Why might we question Hutchinson’s definition of niche?
A
- measurement of niche volume is a subjective procedure,
- some important dimensions of the niche may be not known,
- niches change in the life-cycle,
- niches change from one geographical region to another.
4
Q
What concept did MacArthur’s Warbler observations introduce to niche theory?
A
Limiting similarity- there is a limit to the degree that niches occupied by coexisting species can overlap.
5
Q
What are key the problems inherent in studying niches observationally, like in the case of MacArthur’s Warblers?
A
- measurement of niche volume is a subjective procedure,
- some important dimensions of the niche may be not known,
- niches change in the life cycle,
- niches change from one geographical region to another
6
Q
What is a climate envelope model?
A
A type of model which uses climate variables to make spatial predictions of environmental suitability for a species by extrapolating an index of environmental suitability for a species from a map of environmental conditions.
7
Q
What are the limitations of climate envelope modeling?
A
- Knowledge- Necessary to incorporate traditional ecological knowledge (expert knowledge) into climate envelope forecasts.
- Physiology- Species distributions affected by processes of acclimatization and plasticity. So, predictions based on climate envelopes may be misleading if species physiologies are missed.
- Biotic effects- Species distributions are affected by the interactions with other species. So, predictions based on climate envelopes may be misleading if species interactions are altered by climate change
8
Q
What does this equation mean?
A
Number of individuals at time step t = e^((births-deaths)) x time) x number of individuals at time step 0
Simple exponential model of population growth which assumes population growth can be described purely based on births-deaths (intrinsic rate of increase, r).
9
Q
What do these equations mean?
A
Two alternative methods of introducing temperature dependence into simple exponential model of population growth. Simple models of fundamental niche, only one environmental factor influencing intrinsic rate of increase.
10
Q
What does this equation mean?
A
Logistic model of population growth, which introduces density dependence.
11
Q
For quantitive (determined by many genes) traits, how will the fitness of individuals be distributed around the optimum phenotype?
A
Fitness is normally distributed around the optimum.
Width of curve, ω= ecological tolerance.
12
Q
What does these equations mean?
A
Describe the response of a population to selection (new optimum phenotype), based on amount of genetic variation present in the population and strength of selection.
13
Q
Which form of genetic variation contributes to selection in quantitative traits?
A
Additive genetic variance- average effects of individual loci all contribute to the trait
14
Q
When the optimum phenotype of a quantitative trait changes, what conditions make a population more likely to survive?
A
- High additive genetic variance
- Shallow selection gradient
15
Q
How can covariance of traits influence a populations response to selection (assuming trait is quantitative
A
16
Q
What is covariance?
A
Some of the same genes influence variation in two or more separate traits.
17
Q
How can phenotypic plasticity impact genetic responses to selection?
A
- Plasticity can increase chance of surviving and give chance for genetic adaptation. i.e. Genetic assimilation – a plastic change becomes genetically based over time
- Can limit genetic response by weakening selection pressure on genetic changes.
18
Q
What does λ represent in demographic population modeling?
A
λ = the rate of change of a population over time
λ>1 population is growing
λ=1 population is stable
λ<1 population is shrinking
19
Q
How do matrix population models differ from integral projection models? (Both are discrete-time, structured population models.)
A
Matrix population models use discrete categories to classify individuals, whilst integral projection models use continuous data.
20
Q
How do Leslie and Lefkovitch matrix population models differ?
A
The Leslie model is age-based, and so linear, whilst the Lefkovitch is life-stage based meaning individuals can retrogress to previous stages under certain circumstances
21
Q
Explain the Leslie matrix population model
A
22
Q
Explain the Lefkovitch matrix population model
A
23
Q
How can a matrix population model be used to calculate the size of a population at Nt+1, based on the population at Nt?
A
Nt+1 = A x Nt
24
Q
How does the sensitivity of a model element differ from its elasticity?
A
Sensitivity- degree to which perturbing different matrix elements of the model with a fixed intensity alters the outcome of the model
Elasticity- degree to which perturbing different matrix elements of the model with an intensity proportional to the value of the element alters the outcome of the model
25
How can density dependence be incorporated into a matrix population model?
Rather than assuming vital rates such as survival and fertility are fixed values, we can make them variables, and collect data on how these rates change depending on population size
26
How can environmental stochasticity be incorporated into a matrix population model?
We can project the environmental conditions at each time step, and therefore the associated growth rate.
There are many different ways to produce stochastic projections of future conditions
27
What value is used instead of λ in stochastic matrix population models?
a = the mean of log of λ values at each time step
28
In what three ways do organisms expend energy according to the kappa - rule model?
1. Assimilation budget - energy necessary to gather food
2. Somatic maintenance - energy necessary to maintain and develop body
3. Maturity maintenance - energy invested in maintaining reproductive organs and producing young.
29
What logical assumptions are made by a kappa - rule dynamic energy budget?
1. Energy uptake is a function of an organism's size
2. Bigger individuals in a species can uptake more energy
3. Bigger individuals use more energy
4.at some point organisms stop growing when maintenance = energy available for soma ( none left for growth )
30
What are the main criticisms of the dynamic energy budget models?
1. Assumption that kappa (proportion of energy allocated to youth) remains the same is often violated
2. Lots of parameters necessary in full model
3. Variables are very difficult to measure accurately
31
How does the approach used in life history based models differ from the approach used dynamic energy budget models?
Instead of focusing on resources, focus on statistical associations between body size and demography
32
What is the stress gradient hypothesis?
The frequency of facilitative and competitive interactions varies inversely across abiotic stress gradients. (organisms in more stressful environments are more facilitative)
33
What is the competitive exclusion principle?
No two species can coexist it hey share the exact same niche
34
Explain the Lotka-Volterra Predator-prey model
35
According to the Lotka-Volterra Predator-prey model when will two species study coexist?
36
What forms of species mismatch can be induced by climate change?
1. Temporal mismatch- species respond to climate change at different rates, leading to species becoming temporally isolated from eachother
2. Special mismatch- species differ in their sensitivity to temperature and their ability to change their range, resulting in spatial isolation
37
How do the Red Queen and Court Jester hypotheses differ?
The Red Queen hypothesis argues that biotic factors have been the most significant selection pressures for life on Earth. Meanwhile, the Court jester hypothesis argues that abiotic factors have been the most significant.
38
What is coevolution?
Coevolution: Change in the genetic composition of one species in response to genetic change in another (reciprocal evolutionary change in interacting species)
39
How could competition alter species' adaptation to climate change?
- Competition could inhibit evolution (already other species with suitable traits for new conditions)
+ Competition could amplify evolution (trait changes to adapt to new climate trigger co-evolution of niche traits)
40
What features are necessary in a simple model of a community facing global warming?
1. Set of coexisting species, with species initially adapted to conditions in each patch
2. Species traits that determine match to a specific environment
3. Traits can evolve
4. Environment changes.
41
What conclusions can be reached based on a simple theoretical model of species interactions in communities facing global warming?
1. How species respond depends on evolutionary rate versus dispersal.
2. Species diversity inhibits adaptation and diversification.
Experimental evidence suggests that diversity can stimulate evolution instead
42
Is the conclusion that species diversity inhibits evolution, as predicted by our simple theoretical model borne out by experiment data?
Experimental data suggests the opposite:
1. Bacterial communities isolated from beach tree-holes evolve more rapidly in communities than monoculture.
2. There was a trade-off between success in monoculture and success in community.
3. Strains which evolved in communities became more cooperative and there was enhanced partitioning of resources, entrancing overall ecosystem functioning.
43
What two evolutionary dynamics can emerge from parasitism?
1. Cyclical: current parasite is best at infecting current host and current lost is most resistantto current parasite
2. Escalation: future host most resistant to current parasite. Future parasite most infections to current host.
44
Why in an experiment on parasitism using bacteria and phages did the bacteria in the community with the most phages evolve resistance fastest?
Strongest selection gradient.
45
What is a native species?
Native species: species which become part of an ecosystem through natural processes (without human interference )
46
What three criteria must a species fulfill to be considered invasive?
1. Introduced: arrival can be attributed to human activity
2. Naturalised: can reproduce in new ecosystem
3. Invasive: spread from introduction site and have a negative impact
47
What is the 10s rule?
Of all species that are introduced to a new location 10% escape, 10% of those reproduce and 10% of those spread.
48
What is the enemy release hypothesis?
Introduced species experience a decrease in regulation by herbivores and other natural enemies, resulting in a rapid increase in distribution and/or abundance.
49
What is the novel weapons hypothesis?
Invasive species can have a competitive advantage against native species because they possess a novel weapon, i.e. a trait that is new to the resident community of native species and therefore affects them negatively
50
How can invasive species potentially interact with native ones?
Direct links
To be successful, invaders must consume resources in the recipient ecosystem. Many are omnivores, feeding across multiple trophic levels, invaders can also become a resource to native consumers often creating novel trophic pathways
Indirect links: trophic cascades
When an invasive species acts as a resource for a native species, it can cause a cascade where the newly more abundant native species is consumed by upper trophic levels.
Alternatively, a new invader at the top of the food chain will not only affect its direct prey but also lower trophic levels because of a release from predation or herbivory pressure.
Indirect links: competition
An invader may compete with a native consumer for the same resource due to limited resource availability (apparent competition) or antagonistic interactions (interference competition).
Indirect non-trophic effects
Some invasive species alter the avoidance behaviour of native prey, and therefore its interaction with a native predator. In addition, can alter community structure or habitat complexity with implications for native species foraging behaviour.
51
What is the island susceptibility hypothesis?
Invasive species are more likely to become established and have major ecological impacts on islands than on continents. This is also known as ‘biotic resistance’ since continents typically have higher biodiversity than islands, mainly due to geographic and thus evolutionary isolation
52
What are the requirements for stability within an ecosystem?
1. Something limits each population in the network (food, predation etc.)
- Keeps population within bounds
2. Stabilizing, negative frequency-dependent, or no selection
- Means no one allele (or genotype) grows to fixation. Alleles fluctuate in frequency with time
2. Antagonistic interactions result in coexistence mechanisms
- Stabilizing mechanisms (niche differentiation), equalizing mechanisms (different relative performances on different parts of shared niche), storage effect, relative non-linearity (different relative performances as environment fluctuates)
53
What two features typify an ecosystem at equilibrium?
1. No temporal trend in population dynamics of any species in the network
2. No long-term trend in mean values of phenotypic traits (or underlying alleles) with time in any species in the network
54
What is a trophic cascade?
Perturbation of an ecosystem due to increase or decrease in population of a top predator, resulting in a range of direct and indirect effects throughout the ecosystem.
55
What types of direct and indirect effects can result from a trophic cascade?
1. Density-mediated direct effect: variation in population size of one species -> change in population size of directly interacting species
2. Trait-mediated direct effect: variation in population size of one species alters phenotypic trait expression in a directly interacting species (e.g. landscape of fear)
3. Density-mediated indirect effect: Presence / absence of a predator
-> change in number of prey -> influence on resources of the prey
4. Trait-mediated indirect effect: Presence / absence of a predator -> phenotypic trait expression of prey -> influences the resources of the prey
56
What are the two main types of ecosystem regulation, and how does the type of regulation in an ecosystem influence its susceptibility to trophic cascades?
Top-down regulation: consumers are predator-regulated
Bottom-up regulation: consumers are food-regulated
Types of dynamics depend on balance between top down and bottom up regulation. Most extreme trophic cascades occur when initial state is top down, and predator loss results in bottom-up regulation. Highly bottom-up regulated ecosystems, such as the Serengeti, can be very resilient to trophic cascades.
57
What are three approaches to selecting protected areas?
1. Hotspots- Select areas with highest species richness.
2. Threatened species hotspots- Select places where threatened species occur.
3. Gap Analysis- Priorities areas which have unique sets of species not protected elsewhere.
58
Outline the Systematic Conservation Planning approach to selecting protected areas for a region
1. Compile data on the biodiversity of the region § particularly for rare / threatened species
2. Set conservation targets for the region
- e.g. aim to protect at least 3 sites where each species occurs
3. Review existing conservation areas
- Are targets already met?
- Are current PAs and potential future PAs secure?
4. Select additional conservation areas
- Identify sets of new conservation areas for consideration
59
What are the two main goals of when developing a theoretical approach to protected area/reserve design?
1. maximise diversity
2. minimise extinction in the reserves
60
The principles laid out in MacArthur and Wilson’s 'The Theory of Island Biogeography' can be applied to protected areas, with protected areas being analogous to islands. What are the recommendations of the island analogy in for maximizing diversity and minimizing extinctions in protected areas.
The equilibrium number of species depends on area and isolation:
- Area should be as large as possible
- Reserves should be close together
61
A single big protected area is better than a single small one, but shout we have a Single Large reserve or Several Small reserves with the same total area?
FOR SINGLE LARGE:
- Lower extinction risks
- Large-bodied species need large home ranges
AGAINST SINGLE LARGE:
- Stochastic events
- Disease
- May have lower total species richness
62
What are the arguments for round reserves vs. for long, thin reserves?
Round reserves:
- reduces edge effects
- makes dispersal within the reserve easier and reduces ‘accidental’ emigration
Long, thin reserves:
- are likely to contain more species than rounded ones of the same area (beta diversity is greater).
63
Habitat corridors serve to link protected areas together, which is particularly important for maintaining migration routes. What are some of the issues with habitat corridors?
*Do species use them?
*Spread of diseases
*Synchronizes population dynamics
- Environmental stochasticity can affect all reserves simultaneously
*Can act as a ‘sink’ habitat
*Can be very expensive
- Instead, increase the area of existing reserves, buy new reserves, or manage existing reserves better
64
What are some of the issues with theoretical 'rules' for reserve design
1. The theory and the rules are concerned with maximising diversity
- in practice, reserves are more likely to be designed with particular threatened species in mind
2. Conservation in the real world is opportunistic – difficult to apply many of the rules in practice
3. Reserves aren’t the only way of conserving species – Reconciling economic activity and conservation
4. People need to be integrated into reserve designs
65
What is a biosphere reserve?
Reserve characterized by zonation of land uses- interior fully protected, surrounding area is managed with some human economic activity:
66
What are some of the issues that make protected areas less effective?
1. Many Protected Areas are ‘paper parks’- exist in theory but are not enforced.
2. It can be difficult to monitor the effectiveness of PAs
- PAs often in inaccessible areas where forest threats are low
- Deforestation can be displaced: ‘leakage’
67
Humid rainforests cover 6% of land surface, yet support >50% of plant and animal species. What are three models which can explain the high diversity in tropical rainforests, and which is supported by phylogenetic analysis?
1. Ancient cradle: decrease in diversification since origin with early radiation
2. Museum model- Constant diversification rate & old lineages persist through time
3. Recent cradle: increase in diversification rate since origin with recent radiation
Phylogenies, e.g. of tropical forest palms, suggests constant gradual diversification, consistent with museum model.
68
What are secondary forests, and how will increasing urbanization impact them?
Secondary forests- forests which grow in an area of previous clearance/disturbance.
UN data and projections suggest that urban populations of developing nations will soon exceed their rural populations. Increasing urbanisation will cause secondary forest to expand, cushioning the effects of deforestation
69
What are some of the options available when making rainforest conservation economically viable for local communities, and what are some of their issues?
1. Sustainable exploitation- e.g. non timber forest products.
Issues: unforeseen impacts, for example intensive collection of Brazil nuts results in lower juvenile recruitment, producing an increasingly aging tree population .
2. Bioprospecting
Issues: High profile deals such as the 1991 Merck-INBio agreement have yet to yield any major discovery.
3. Ecotourism
Issues:
- Benefits tend to accrue to a minority (often outsiders)
- Can have detrimental effects
- Vulnerable to political and financial instability
70
Which approach to rainforest agriculture is more effective as a conservation strategy, Land sparing (intensity + protected areas) or Land Sharing (“Wildlife-friendly” farming)?
Data from Sabah, Borneo suggest that ”land sparing” may be a better strategy for conservation than “land sharing”
Changes in species abundance under different logging scenarios. Bars show the numbers of species that have significantly higher abundance under one scenario relative to the other, as well as species that show non-significant differences between scenarios
71
What are eco-evolutionary feedbacks?
Reciprocal interactions between the ecology of populations communities and ecosystems, and the evolution of organismal traits
72
What two components are necessary for an eco-evolutionary feedback to arise?
1. Eco-evolutionary change: A species evolving in response to change in ecology
2. Evo-ecological change: Evolution of a species generates ecological change for itself or other species
Eco-evolutionary feedbacks arise when eco-evo change and evo-eco change both occur.
73
What features of a community can prevent eco-evolutionary feedbacks from forming?
1. Lack of genetic variation
2. Incongruent timescales (e.g. if species interactions are intermittent and do not persist long enough for evolution to occur)
3. Communities in their steady state i.e. eco-evo feedbacks may have played out – need to perturb a system and see how it returns to equilibrium
4. Where per capita interactions are weak, or a species is rare – less likely to produce eco-evo feedbacks
5. Where effect size is weak e.g. short duration
74
What are niche construction and ecosystem engineering?
Where an organism alters the environment such that it changes the form and strength of selection on itself (niche construction) or other species (ecosystem engineering)
75
How can eco-evo feedbacks be researched using the Trinidadian Guppy??
1.Natural populations – replicated streams with and without predators
2. Experimental introductions in natural systems
3. Wild guppy demography: capture-mark-recapture
4. Mesocosm experiments – semi- natural, situated in field conditions, but manipulations possible
5. Lab experiments – remove environmental variation
76
What are three ways in which Island communities differ from continental ones?
1. Depauperate: lower number of species overall. Function of area (and limits on habitat heterogeneity) & isolation.
2.Disharmonic: Some functional groups particularly under- or unrepresented e.g. Predators & parasites
3. Density-inflated: Higher population densities than similar sized area of mainland In some cases, total densities of multiple species on islands within a guild may exceed that of many more species on mainland – density compensation
77
How does the dominant form of biotic interaction on islands differ from those on the mainland?
Mainland: interspecific competition; predation; parasitism
Island: intraspecific competition
78
What are the features of Island syndrome?
79
What is the Island Rule? Why is it controversial?
1. Tendency to display evolution towards medium body size in insular settings.
2. Controversy- Not ubiquitous, upheld for some taxa more than others, e.g.
- Birds- depends on size of island
-Mammals- not present in carnivores
80
What are 4 key ways in which the selective pressures facing island populations differ from those on the mainland, and what traits are traditionally associated with these differences?
1. Reduced interspecific competition: wider niche; higher densities.
2. Reduced suite of parasites and predators: graviportal phenotypes, behavioral naïveté;
2. Increased intraspecific competition: reduced territoriality & aggression.
3. Reduced need/advantage for dispersal: rounded wings; flightlessness.
81
Low-gear locomotion amongst island mammals was traditionally assumed to be due to a lack of predators removing the need for maneuverability. What did an analysis by Rozzi et al. (2020) find to be the primary driver instead?
Number of competitors (not predators) was the primary driver, with island topography also featuring.
82
The island rule traditionally stated that a lack of competition results in individuals converging on a large-bodied, generalist phenotype, as large individuals can access a broader range of resources. What are the issues with this assumption?
When viewed at a population level, it is impossible to distinguish between individual generalists, and individual specialists all occupying different niches.
In some island populations, e.g. Heron island Silvereyes, the latter appears to be the case
83
What evidence is there for Island syndrome being an evolutionary trap?
Island species are over- represented in extinctions:
* 95% of terrestrial bird and mammal extinctions since 1500 have been island species (Loehle & Eschenback 2012)
* Predators (incl humans) and disease are a major cause (+ habitat loss and modification)
84
What life history traits are predicted to be most successful in a purely stochastic environment?
1. Short lifespan
2. Fast senescence
3. Body size small or fluctuating
4. Reproduction early:
-As an individual gets older, it produces more offsprings but its probability of survival decreases. This tradeoff can be modelled to predict an evolutionary stable strategy.
5. Many offspring with little parental care.
85
What are the iteroparity and semelparity?
Iteroparity- reproductive strategy characterised by many reproductive episodes
Semelparity- reproductive strategy characterised by a single reproductive episode
