Evolution and Population Genetics Practice Flashcards

Vocabulary flashcards covering the principles of Hardy Weinberg equilibrium, Darwinian postulates, modes of natural selection, and factors causing evolution as described in the lecture transcript.

Evolution

A change in the frequency of alleles (and/or genotypes) in a population.

Hardy Weinberg's equilibrium formula

$$p^2 + 2pq + q^2 = 1$$

Hardy Weinberg's equilibrium requirements

Random mating, no selection, no genetic drift, no mutation, no gene flow, and a big population.

Hardy Weinberg null hypothesis

States that evolution is not happening and that allele and genotype frequencies will remain the same across generations.

Darwin's four postulates

1. Individuals vary. 2. Variation is heritable. 3. More individuals are born than will live to reproduce. 4. Certain traits lead to higher survival and reproduction.

Evidence of Natural Selection

Geology and age of Earth, extinction, current changes in populations, biogeography, transitional features, vestigial features, homologies, and current speciation.

Charles Lyle

One of Darwin's inspirations; associated with the age of Earth.

Malthus

Inspiration for Darwin regarding artificial selection.

Lamarckian evolution

A theory describing evolution as progressive and linear (the 'great chain of being') where individuals change rather than populations.

Population thinking

A revolutionary concept of Darwin and Wallace's theory that distinguishes it from Lamarckian ideas, emphasizing that populations change, not individuals.

Inbreeding

Non-random mating that does not cause evolution but leads to an increase in homozygosity, which can cause genetic disorders or inbreeding depression.

Directional selection

A mode of natural selection that shifts a trait up or down (e.g., bigger or smaller body size) and can involve purifying selection.

Stabilizing selection

Selection towards the mean that reduces variability; occurs when extremes have higher mortality (e.g., baby size).

Disruptive selection

Selection that increases variation and can be bimodal, occurring when the intermediate phenotype is the least beneficial; can cause speciation.

Balancing selection

A mode of selection where no single allele has a benefit, often occurring when the heterozygote is more fit.

Genetic drift

Evolutionary change caused by randomness and breaking the infinite population requirement; has a bigger impact in smaller populations.

Founder effect and Bottleneck effect

Specific causes of genetic drift where the loss of one allele or another is random rather than based on fitness.

Gene flow

The movement of alleles that equalizes allele frequencies between two populations; can have positive or negative impacts depending on shared genes.

Fundamental asymmetry of sex

The concept that females have a larger investment in offspring (eggs) and produce limited offspring, leading to mate choice.

Sexual dwarfism

A physical result of sexual selection, which often involves males competing for mates and females choosing mates.

Constraints on natural selection

Nonadaptive traits, genetic constraints, and fitness trade-offs.

Pre-Darwinian theories of life

Special creation, typological thinking, and the great chain of being.