Lecture 9 - Ecological Theory

Question 1

What was originally thought about the effect of ecological interactions on evolution?

Answer 1

They were thought to have been ‘too rapid’ to have any impact on evolution.

Question 2

Describe the work of Slobodkin, 1961.

Answer 2

Drew a distinction between ‘ecological time’ (10 generations) and ‘evolutionary time’ (half a million years).

Question 3

Describe the work of an evolutionary biologist that showed that ecology influenced evolution.

Answer 3

Kettlewell (1955).

Study of how peppered moth became black during Industrial Revolution.

Question 4

What was the name of the publication of Richard Levins, and the date published?

Answer 4

‘Evolution in Changing Environments’, 1968

Question 5

What were the beliefs of Richard Levins?

Answer 5

That organisms evolve in the context of their environments (environments are not static).

Question 6

Who introduced the theory of Adaptive landscape?

Answer 6

Sewall Wright (1932)

Question 7

What is the theory of adaptive landscape?

Answer 7

That natural selection moves populations to adaptive peaks/optima.

Question 8

When is the adaptive landscape said to be static?

Answer 8

If evolution occurs independently of the environment

Question 9

What are three major life history traits likely to influence reproductive success?

Answer 9

• Age at first reproductive event
• Reproductive lifespan
• Number and size of offspring

Question 10

Describe the life history of a Darwinian Demon.

Answer 10

• Produces many offspring
• Can reproduce soon after birth
• Reproduces every year
• Lives forever

Question 11

Why don’t organisms maximise the fitness of all life history traits simultaneously?

Answer 11

Energy resources are limiting, and evolution is constrained by trade-offs.

Question 12

Who described the Principle of Allocation?

Answer 12

Levins (1968)

Question 13

Describe the Principle of Allocation.

Answer 13

If an organism allocates energy to one function, it reduces the amount of energy available to other functions, such as reproduction.

Question 14

What is a trade-off?

Answer 14

A situation where a fitness-increasing change in one trait is linked to a fitness-decreasing change in a different trait.

Question 15

Give Levin’s equation for the expected number of offspring.

Answer 15

Expected no. offspring = rate of reproduction x expected life span

Question 16

In Levin’s theory, as rate of reproduction increases, what should happen?

Answer 16

Survivorship of the organism should go down.

Question 17

Describe Levin’s experiment o reproduction vs survivorship.

Answer 17

• 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.

Question 18

What is pleiotropy?

Answer 18

One allele influences two or more seemingly unrelated phenotypic traits.

Question 19

What is The Antagonistic Pleiotropy Hypothesis?

Answer 19

If an allele causes both increased reproduction in early life and ageing in later life, then senescence would be adaptive in evolution.

Question 20

Who proposed the Antagonistic Pleiotropy Hypothesis?

Answer 20

George C. Williams (1957)

Question 21

What can be said about Guillemots investing heavily in reproduction early in life?
What is this evidence of?

Answer 21

They had significantly reduced breeding success in the senescent years.

Evidence of antagonistic pleiotropy

Question 22

What was the original claim about the Methuselah gene?

Answer 22

A single mutation allowed flies to live 35% longer.

Question 23

What is the trade-off with Drosophila mutants with the Methuselah gene?

Answer 23

• Live longer
  BUT
• Laid fewer eggs earlier in life, and reduced reproductive success.

Question 24

How are effects of the Methuselah gene altered at decreased temperature?

Answer 24

Methuselah mutants at reduced temperature show higher reproductive success than wild type individuals.

Question 25

Describe the theory of Disposable Soma.

Answer 25

There is a trade-off between reproductive survival and maintenance of the somatic tissues.

Question 26

What is the Mutation Accumulation Theory?

Answer 26

Random, detrimental germline mutations show their effects only later on in life.

Question 27

what is the Rate of Living Theory?

Answer 27

The faster the metabolism, the shorter the lifespan.

Question 28

Who proposed the Mutation Accumulation Theory?

Answer 28

Medawar 1952

Question 29

Who proposed the Rate of Living Theory?

Answer 29

Rubner 1908