ST Lectures: Natural And Sexual Selection:

Question 1

What is natural selection?

Answer 1

A mechanism of evolution where individuals within a population with certain traits are more or less likely to survive and reproduce than those without the traits

Question 2

What is sexual selection?

Answer 2

A mechanism of evolution where individuals within a population with certain heritable traits are more or less likely to obtain mates and have reproductive success than individuals of that population that have differing heritable traits.

Question 3

How are natural selection and sexual selection similar?

Answer 3

1. Both natural selection and sexual selection rely on variation within populations
2. The variations in the individuals in populations must be heritable
3. Overproduction of offspring = more offspring are produced then can survive
4. Survival is non random = individuals with advantageous traits have higher fitness

Question 4

How are natural and sexual selection different?

Answer 4

1. Variation in natural selection focuses on traits that affect survival and overall fitness, whereas, variation in sexual selection is due to traits that influence mating success
2. Heritability favours the inheritance of traits that increase survival in natural selection and favours traits that increases mating success in sexual selection, even if they may sometimes be detrimental to survival
3. Non-random survival in sexual selection is due to individuals have traits that are more attractive to mates, whereas, success in natural selection is due to traits that enhance an individuals survival

Question 5

What is an example of inter-sexual selection?

Answer 5

Courtship behaviours in male Drosophila to attract a female

Question 6

What is an example of intra-sexual selection?

Answer 6

Male-male aggression in Drosophila to compete for females

Question 7

What is necessary for natural selection to create evolutionary change in a population over time?

Answer 7

1. Variation with the plumage colouring of Kakapo individuals
2. This variation in plumage is heritable, an depends on what colour is more favourable for survival
3. Some individuals are more successful at surviving and reproducing than others
4. The success of the individuals is non-random and related to them having the more favourable coloured plumage e.g., camouflaged