Midterm 1: Simple Evolution Terms

What is Population Genetics

The study of naturally occurring genetic differences among organisms

Study of polymorphism

Examines genetic variation within populations to understand evolution and selection.

Study of divergence

Genetic differences between populations or species to understand evolution and selection.

Spandrels Metaphor

Not all traits are direct adaptions

Panglossian Paradigm Methapor

Tendency to assume that every biological trait is an optimal adaptation produced solely by natural selection for a specific purpose.

Adaptation

A characteristic that increases survival or reproduction compared to alternative traits; evolves by natural selection.

Natural selection

Any consistent difference in fitness among individuals or groups with different traits.

Fitness

The number of offspring an individual contributes to the next generation; includes survival and reproduction.

Conditions for natural selection

• Phenotypic variation exists

• Variation affects fitness

• Variation is heritable

Difference between hybridization and introgression

Hybridization creates hybrids; introgression occurs when genes from hybrids spread and persist in a population over generations.

What are most new mutaions?

Deleterious

3 hypothesis about the nature/role of genetic variation

1) Classical hypothesis

2) Balance hypothesis

3) Natural theory of molecular evolution

major forces in biological evolution?

• Mutation

• Natural selection

• Random sampling

• Migration & gene flow

• Recombination

What are some major factors that affect the amount of genetic variation

• species and/or population

• The phenotype- sequence code??, fitness effect??

• Genome/chromosome region

Main Assumptions of Hardy-Weinberg principle

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1. Diploid organisms
2. Sexual reproduction
3. Non-overlapping generations
4. Two alleles
5. Allele frequencies same in males and females
6. Random mating
7. (Infinite) Large population size
8. No migration
9. No mutation
10. No selection

Factors that affect mutation rate

• environment

• sex

• age

• species

What is the key difference between genetic and nongenetic effects on mutation rate?

Genetic effects are inherited and can evolve; nongenetic effects (i.e Environmental or random factors) are temporary and do not evolve.

What is a polygenic trait?

A trait controlled by many genes, each contributing a small effect to the phenotype.

Heritability

The proportion of phenotypic variation in a population that is due to genetic variation and explains resemblance between parents and offspring.