Lecture 11 Natural selection _Patterns and constraints

Question 1

Directional selection is

Answer 1

Phenotypes of one extreme is preferred to have the highest fitness. Extreme that are the lowest fitness does not carry on trait. Changes overal mean trait

Question 2

Disruptive/diversifying selection:

Answer 2

When both extremes have the highest fitness or frequency. Results increase in variance.

Question 3

Stabilizing selection

Answer 3

phenotypes that are average have the highest fitness. This reduces trait variation

Question 4

Sexual selection

Answer 4

traits that specifically enhance reproduction even at the cost of survival. For example, male peacocks in the wild are vunerable to predation, but they make up in sexual selection.

Question 5

Intrasexual Selection

Answer 5

• Male/male or female/female competition
  Winner= tons of offspring ( such as lions)
  Intersexual selection:
  One of the sex is choosing whether to mate.

Question 6

Trade-off in natural and sexual selection

Answer 6

For example bird with long tail is able to mate more with females. However, the longer the tale the less mobile and there is a limit to how far the tail can grow where they are completely vunerable to predation or having too much high mortality.

Question 7

Why is one of the sex choose?

Answer 7

The reason is because one of the sex usually females end up investing more energy and time to produce and raise off-spring.
One that is selected: usually males are the ones to be selected because they invest less and compete for mates
- However, some species have were both the male and female or male dedicates more energy to raise off-spring.