Ecological theory of evolution 2

Question 1

Describe the study of yoshida

Answer 1

Mathematical prediction of ecological dynamics.
Found: cycle length is longer than predicted. Predator and prey densities are out of phase.

Question 2

What did Levins say?

Answer 2

Organisms evolve in the context of their environments

Question 3

What is Levins’ classical theory of evolutionary ecology

Answer 3

Evolution proceeds as to realise an optimum strategy - some quantity is maximised during the course of evolution.
How do we choose this quantity? Often assumed that evolution maximises the basic reproductive ratio R0

Question 4

What is R0?

Answer 4

The expected number of infectious contacts made by a singe infected individual introduced into a suseptible population

Non disease: the expected number of offspring per individual

Question 5

How to calculate R0?

Answer 5

R0 = rate of reproduction x expected lifespan

Expected lifespan = 1/rate of death

so, R0 = the rate of reproduction/the rate of death

Question 6

How to calculate R0 for a virus?

Answer 6

R0 = the rate at which an infected individual makes an infectious contact x the expected length of time that the infective individual remains infectious

expected length of time = 1/rate of death (or recovery)

R0 = the rate at which an infected individual makes an infectious contact/ / the rate of death or recovery

> 1, epidemic occurs

Question 7

What is Levins theory regarding R0

Answer 7

Evolution maximises R0

Strong evidence a virus cannot improve both components

Question 8

Give an example of reproduction suvivial

Answer 8

E.coli viruses

As multiplication rate increases, so does mortality rate

Question 9

Describe the graphical method for finding an optimal strategy

Answer 9

Evolution proceeds as to realise an optimum. The shape of the trade-off matters

Trade-off curve describing the relationship between the reproductive capabilities in the two environments.
Counters of the fitness landscape; all the points in trait space that yield equal fitness

Question 10

What is the optimal phenotype?

Answer 10

The strategy that lies on the intersection of the boundary space and the highest contour

Question 11

What are the conclusions from graphical method?

Answer 11

Concave trade-off: intermediate strategy is optimal

Convex: one of the two boundary strategies is optima

Question 12

Describe estimating trade-off shape

Answer 12

Trade-off between competitive ability and resistance to enemies
Improving resistance to an enemy decreases the organism’s competitive ability

Question 13

What does a concave shape represent

Answer 13

Resistance increases with the fitness of some passive barrier

Question 14

What does convex represent

Answer 14

Resistance increases by activating the immune system, but the costs decreases with recruitment of haemocytes