Lecture 9 - Ecological Theory Flashcards
What was originally thought about the effect of ecological interactions on evolution?
They were thought to have been ‘too rapid’ to have any impact on evolution.
Describe the work of Slobodkin, 1961.
Drew a distinction between ‘ecological time’ (10 generations) and ‘evolutionary time’ (half a million years).
Describe the work of an evolutionary biologist that showed that ecology influenced evolution.
Kettlewell (1955).
Study of how peppered moth became black during Industrial Revolution.
What was the name of the publication of Richard Levins, and the date published?
‘Evolution in Changing Environments’, 1968
What were the beliefs of Richard Levins?
That organisms evolve in the context of their environments (environments are not static).
Who introduced the theory of Adaptive landscape?
Sewall Wright (1932)
What is the theory of adaptive landscape?
That natural selection moves populations to adaptive peaks/optima.
When is the adaptive landscape said to be static?
If evolution occurs independently of the environment
What are three major life history traits likely to influence reproductive success?
- Age at first reproductive event
- Reproductive lifespan
- Number and size of offspring
Describe the life history of a Darwinian Demon.
- Produces many offspring
- Can reproduce soon after birth
- Reproduces every year
- Lives forever
Why don’t organisms maximise the fitness of all life history traits simultaneously?
Energy resources are limiting, and evolution is constrained by trade-offs.
Who described the Principle of Allocation?
Levins (1968)
Describe the Principle of Allocation.
If an organism allocates energy to one function, it reduces the amount of energy available to other functions, such as reproduction.
What is a trade-off?
A situation where a fitness-increasing change in one trait is linked to a fitness-decreasing change in a different trait.
Give Levin’s equation for the expected number of offspring.
Expected no. offspring = rate of reproduction x expected life span
In Levin’s theory, as rate of reproduction increases, what should happen?
Survivorship of the organism should go down.
Describe Levin’s experiment o reproduction vs survivorship.
- Red deer on Rhum island
- Studied milk hinds (deer that produced and successfully reared a calf) against held hinds (those that didn’t)
- Showed that investment in reproduction had a detrimental effect on survivorship.
What is pleiotropy?
One allele influences two or more seemingly unrelated phenotypic traits.
What is The Antagonistic Pleiotropy Hypothesis?
If an allele causes both increased reproduction in early life and ageing in later life, then senescence would be adaptive in evolution.
Who proposed the Antagonistic Pleiotropy Hypothesis?
George C. Williams (1957)
What can be said about Guillemots investing heavily in reproduction early in life?
What is this evidence of?
They had significantly reduced breeding success in the senescent years.
Evidence of antagonistic pleiotropy
What was the original claim about the Methuselah gene?
A single mutation allowed flies to live 35% longer.
What is the trade-off with Drosophila mutants with the Methuselah gene?
- Live longer
BUT - Laid fewer eggs earlier in life, and reduced reproductive success.
How are effects of the Methuselah gene altered at decreased temperature?
Methuselah mutants at reduced temperature show higher reproductive success than wild type individuals.
