Selection and Fitness

Question 1

What are adaptive traits?

Answer 1

product of natural selection that increases the relative fitness of an organism in its environment

Question 2

What is adaptation?

Answer 2

accumulation of adaptive traits over time, can range from molecular to ecological

Question 3

What is meant by the heterozygote advantage?

Answer 3

heterozygotes have a higher relative fitness

Ex. gene for sickle cell leads to a resistance to malaria in heterozygotes

Question 4

What is meant by selection in different environments?

Answer 4

genetic variation is maintained when different alleles are favoured in different places

Question 5

What is balanced polymorphism?

Answer 5

2 or more phenotypes are maintained in fairly stable proportions over many generations

Question 6

What are the 3 conditions through which natural selection preserves balanced polymorphism?

Answer 6

1. Heterozygote advantage
2. Selection in different environments
3. Rarity of phenotype provides advantage

Question 7

What are the 3 factors contributing to adaptive evolution?

Answer 7

• no organisms can be perfectly adapted to its environment because its environment changes
• natural selection acts on existing variations and new mutations
• microevolution focuses on the variation, selection, selective advantages and natural selection at population level

Question 8

Why does natural selection violate the H-W principle?

Answer 8

inherited traits allow some organisms to survive better than others