Chapter 19 – Evolution of Life I: How Populations Change from Generation to Generation - Comprehensive Notes

Evolution

Change in one or more heritable characteristics of a population from one generation to the next

Selective Breeding

A human-driven process of changing the genetic information and characteristics of a population over time

Fossils

Preserved remains of past life; provide evidence of the history of life on Earth

Biogeography

Study of the geographic distribution of extinct and living species

Convergent Evolution

When two species from different lineages have independently evolved similar characteristics because they occupy similar environments

Homology

Similarity that occurs due to descent from a common ancestor; may involve anatomical, developmental, or molecular features

Gene Pool

Includes all of the alleles for every gene in a population

Population Genetics

Study of the genetic variation within a gene pool and how variation changes from one generation to the next

Polymorphism

Presence of two or more variants for a given character within a population

Single-Nucleotide Polymorphism (SNP)

Smallest type of genetic variation (i.e., a point mutation) that can occur within a gene and is the most common

Hardy-Weinberg Equation

Describes the relationship between allele and genotype frequencies when a population is not evolving: p^2 + 2pq + q^2 = 1

Microevolution

Changes in a population’s gene pool (such as changes in allele frequencies) from generation to generation

Natural Selection

Process by which individuals with certain heritable traits tend to survive and reproduce at higher rates than those without those traits

Fitness (w)

Relative likelihood that one genotype will contribute to the gene pool of the next generation compared with other genotypes; a measure of reproductive success

Directional Selection

Individuals at one extreme of a phenotypic range have greater reproductive success in a particular environment

Stabilizing Selection

Favors the survival of individuals with intermediate phenotypes and selects against those with extreme phenotypes

Diversifying (Disruptive) Selection

Favors the survival of two or more different genotypes that produce different phenotypes

Balancing Selection

Maintains genetic diversity in a population, often through heterozygote advantage or negative frequency-dependent selection

Sexual Selection

Form of natural selection by which individuals with certain traits are more likely than others to engage in successful mating

Genetic Drift

Changes in allele frequencies due to random chance; faster in small populations

Bottleneck Effect

Change in allele frequencies of the resulting population due to genetic drift after a drastic reduction in population size

Founder Effect

Occurs when a small group of individuals separates from a larger population and establishes a new colony

Gene Flow

Transfer of alleles into or out of a population; occurs whenever individuals move between populations having different allele frequencies

Assortative Mating

Individuals with similar phenotypes are more