Lectures 9-10: Microevolution

Define evolution as descent with modification in heritable characters within a population.

Change in heritable traits within a population across generation

Distinguish evolution from other forms of biological change such as plasticity, individual development, and ecological succession

Plasticity: Non-heritable change in phenotype caused by the environment

Individual Development: programmed growth in a single organism

Ecological Succession: community change in species composition Qu

Describe the differences between quantitative and qualitative phenotypic variation.

Quantitative: Height, weight, beak length

Qualitative: blood type, color

Discuss the role of the environment in shaping phenotype.

the environment can change phenotype without changing genotype like in plasticity

Solve problems using the H-W equilibrium equation to determine the frequency and number of (a) the dominant and recessive alleles, and (b) the homozygous dominant, heterozygous and homozygous recessive genotypes in a population.

Do practice problems

Distinguish between the five agents of evolutionary change.

Mutation, gene flow, genetic drift, non-random mating, natural selection

Distinguish between directional, stabilizing and disruptive selection.

Favors one extreme, the middle, and both extremes

Indicate conditions that would resist evolutionary change in a population.

No mutation, no migration, large population, random mating, no selection

Distinguish natural selection from the other agents of evolutionary change, noting that it is the only agent that predictably leads to adaptation.

Natural selection is the only agent that has positive outcomes for a population

Define relative fitness difference.

How well a trait reproduces compared to others in a population

List the different proxies for fitness.

Survival rate, number of offspring produced, number of mates obtained

Be able to determine whether the three necessary and sufficient conditions for natural selection to occur: variation, heritability and fitness differences.

If individuals differ in a trait

If differences are passed down

If some versions help individuals survive/reproduce

Interpret hypotheses of evolutionary adaptation with appropriate caution—i.e., be familiar with the criticisms of the adaptationist program.

1. Easy to claim without evidence'

2. Not all traits are adaptations

3. Multiple hypothesis must be considered