Eco-evo 3: Feedback Flashcards
Importance of Eco-evo feedback
Insights into
- Community composition
- Divergence and speciation
- Ecosystem functioning and nutrients cycling
- Disease dynamics
- Population dynamics
Eco-evo/ Eco-eco change vs eco-evo feedback
Eco-evo change: an ecological change (change in environment or species interaction) which impacts the evolution of a species.
Example: Linchen tree vs no linched due to pollution effecting the colour of moths
Example: hunting causing genetic drift
Example: stone camouflage with Coral. Bleaching leads to selective pressure potentially causing to change colour.
Evo-Eco change: An evolutionary change leading to an ecological change for itself or another species.
Example: The evolution of pesticide resistance changes the ecology of primary producers due to higher levels of herbivory.
Example: invasive species alter evolution of native species -> niche differentiation
Eco-evo feedbacks: reciprocal interactions between ecology and evolution with a system
Example: climate change make larval insects emerge later in spring, causing mismatch between arrival of songbirds and and availability of food resource. Selection on song birds to arrive earlier.
Ecological change, change in selection pressure, genetic change, new ecological change, new selection pressure.
What is required for eco-evo feedback?
1) Strong effect of phenotype on the environment.
The evolved phenotype must change the environment
-> keystone species (e.g. apex predator like wolf)
-> Ecosystem engineers (e.g. beavers and fungi)
-> niche constructors
This leads to:
- habitat modifcation
- Alter interactions
- Changeing nutrient cycling
- Consumption of resources
Ecological context is important as the same phenotype in different environments can lead to different ecological effects.
2) Strong effect of environment on phenotype
- The environment must create a strong selection pressure
- phenotype needs to have low ecological tolerance/ not be plastic
- There must be enough genetic variation that is heritable
Example: clonal/ multi clone algae vs rotifer predators
Example: disease creates selective pressure on host but if not enough genetic diversity in host, resistance cannot evolve-> chance of novel mutations
3) There must be congruent timescales
Example: Alewives
Anadromous alewives
- They live in the sea and move to freshwater to breed
- In the freshwater they eat zooplankton causing the biomass and length to reduce
- When they return to the sea the zooplankton populations recovers.
- Timescale of niche construction is out of step with timescale of evolution
Freshwater alewives
- Dambs can trap alewives in the freshwater all year round
- They reduce the biomass and length of the zooplankton year round and the populations do not have time to recover leading to evolution
- This evolutionary change, changed the ecology for the alewives leading to eco-evo feedback and the alewives evolving to be smaller.
Opportunities for anthropogenically driven eco-evo feedback
Human modification can lead to very strong selection pressures
- Herbicide/ pesticide use
- Wildlife and fisheries extraction
- Invasive species
- Pollution
- Climate change
- Re-introduction of species
Predator prey also lead to eco eco feedback
Example of feedback: herbicide use
Herbicide use can lead to eco-evo feedback use as they have strong direct and indirect effects on phenotypes and community composition.
Herbicides cause eco-evo feedback:
- Non-target above-ground species (e.g. pollinators death or reduction in resources for pollinators -> pollinators evolve physiological tolerance, evolve to avoid fields following spraying
- Target plants (e.g. herbicide resistance)
- Non-target below-ground plants (e.g. shifts in soil microbe)
Herbicide resistance changes ecological interactions (evo-eco feedback):
- Resistance genes can directly affect interaction (e.g. increased susceptibility to herbivorous insects, weaker competitor) -> change in metabolic function
- e.g. may change reproductive timing leading to phenological mismatches
This example shows many different eco-evo/ eco-eco dynamics but it does not show how the system feedback/ links up
How do we study Eco-evo feedback
Characterise the focal organisms
- Ages
- Important phenotypes
- Life history parameters
- Population attributes
- Demographic processes
What is the evolutionary response of this species to change?
- Is there strong selection?
- Are the traits heritable?
What is the ecological response to the evolution of this species?
Community attributes
- interacting species
- abiotic factors
Why might we not see feedback loops?
Lack of genetic variation
Incongruent timescales
Communities in their steady state- eco-evo feedbacks may have played out – need to perturb a system and see how it returns to equilibrium
Where per capita interactions are weak, or a species is rare – less likely to produce eco-evo feedbacks
Where effect size is weak e.g. short duration
Eco- evo feedback example: Trinidadian guppy
Is there eco-evo feedback due to the different levels of predation in guppies?
Useful features
- Short generation time and small
- Competent, live young
- Replicate natural streams in different environments: low predation above waterfalls and high predation below waterfalls
They studied the natural populations in the streams, they studied the guppies in labs and they studied them in mesocosms where they could manipulate the environment.
Do gullies effect their ecosystem?
Guppie’s introduction affected the ecosystem.
- They depleted vertebrate abundance
- They declined and reduced mean size of Killifish populations
Eco-evo:
They evolved into high-predation and low-predation forms in the two environments due to predation. - mark- recapture experiments
High predation: small, large number of offspring, faster swimming
Low predation: large, small number of offspring, slower swimming
Able to show phenotypic differences were heritable
Eco-evo:
Predation impacts the density of guppies and causes them to evolve different way to exploit resources (due to density and not predation).
1) HP: Selectively deplete high-quality vertebrates (Adapted to low density/ low competition)
2) LP: they consume all benthos and are generalist (adapted to high density/ high competition)
Evo- Eco
- This change in exploitation of resources impacts of the ecology of the streams as different compositions of organisms are preyed on by the guppies.
- More excretion in HP guppies
Evo- eco
Guppies evolve in response to their impact on the ecosystem.
- There are evolutionary changes in response to the effect that density regulation has on the ecosystem.
- Example: Male guppies become more colourful in Low Predation environments.
Lecture summary
The study of eco-evo feedback has become important since ecology and evolution and can be viewed on congruent time scales.
There are different factors required for feedback
1) Environments has a strong effect on phenotype
- Congruent time scales
- Heritable genetic variation
2) Phenotype has a strong effect on the environment
- Keystone species/ ecosystem engineers leading to habitat modification/ nutrient cycling modification.
Key examples of eco-evo feedback:
- Herbicide use
- Guppies’ in Trinidad.
- species re introduction
- climate change
- isolation on islands
Eco eco feedback: species introduction
Beavers
Eco change
- reintroduction of breakers leads to habitats modification
- fell trees, dig burrows and lodges, build dam be
- formation go beaver ponds, heterogenous habitat formation, habitat destruction, water quality, water regulation
Eco change
- fish evolve to changed water patterns - altered migration routes
- plants evolve traits to withstand flooding
- reduced predation in juvenile salmon in protected ponds leads to evolution of larger size and growth rates
