Review of Evolution and Natural Selection Concepts

This set of flashcards covers key concepts related to evolution and natural selection, including definitions and important examples from the lecture.

Genetic Variation

Essential for evolution; without it, natural selection cannot act.

Natural Selection

Occurs when individuals with certain phenotypes survive better and reproduce more, leading to changes in allele frequencies.

Absolute Fitness (R)

The expected number of surviving offspring, also known as population growth rate.

Relative Fitness (w)

Fitness compared to another genotype, scaled so that the most fit genotype equals 1.

Directional Selection

Favors one extreme phenotype, causing a shift in the population average.

Stabilizing Selection

Favors intermediate phenotypes and selects against extremes, keeping the mean phenotype the same.

Disruptive Selection

Favors extreme phenotypes and selects against intermediates, increasing variation.

Balancing Selection

Maintains multiple alleles in a population, preserving genetic variation.

Gene Flow

Movement of alleles between populations through migration and breeding.

Genetic Drift

Random changes in allele frequency due to chance events, particularly impactful in small populations.

Founder Effect

Occurs when a small group establishes a new population with allele frequencies that differ from the source population.

Population Bottleneck

Sudden, drastic reduction in population size that leads to a loss of genetic variation.

Inbreeding Depression

A decline in average population fitness due to increased homozygosity from inbreeding.

Assortative Mating

A non-random mating pattern where individuals choose mates based on phenotypic similarity or difference.

Sexual Selection

A form of natural selection that influences mating success rather than survival.

Point Mutation

A change in a single nucleotide in the DNA sequence that can affect protein function.

Chromosome-Level Mutation

Mutations that affect large sections of DNA, including duplications and deletions.

Horizontal Gene Transfer

The transfer of genes between organisms that are not parent-offspring, common in bacteria.

Good Genes Hypothesis

Female choice favors males with traits indicating genetic quality and health.

Purifying Selection

The process of removing deleterious alleles from a population.

Vestigial Trait

A trait that has lost most of its original function through the process of evolution.