SHU_1211_Ch19_Evolution

Evolution

The change in genetic composition of populations over time.

Mutation

Any change in the nucleotide sequences of DNA, the origin of genetic variation.

Natural Selection

The differential survival and reproduction of individuals based on variations in their traits.

Gene Flow

Migration of individuals and movements of gametes between populations impacting allele frequencies.

Genetic Drift

Random changes in allele frequencies, significant in small populations.

Nonrandom Mating

When individuals choose mates based on specific phenotypes.

Hardy-Weinberg Equilibrium

A principle describing a population not evolving, requiring specific conditions to be met.

Stabilizing Selection

Preservation of average phenotype, reducing variation but not changing the mean.

Directional Selection

Favors individuals at one extreme of a phenotypic range, increasing frequencies of certain alleles.

Disruptive Selection

Favors individuals at both extremes of a phenotypic range, increasing variation in the population.

Fitness

The reproductive contribution of a phenotype to subsequent generations relative to other phenotypes.

Heterozygote Advantage

When heterozygous individuals have higher fitness than either homozygous genotypes.

Adaptive Radiation

The rapid evolution of diversely adapted species from a common ancestor.

Speciation

The process of forming new and distinct species in the course of evolution.

Allele Frequency

The proportion of a specific allele among all allele copies in a population.

Polymorphism

The occurrence of two or more clearly different morphs or forms in the population of a species.

Microevolution

A change in allele frequencies in a population over generations.

Macroevolution

Broad patterns of evolutionary change over long timescales.

Prezygotic Isolating Mechanisms

Prevent hybridization from occurring before fertilization.

Postzygotic Isolating Mechanisms

Reduce hybrid offspring's fitness after fertilization.

Artificial Selection

The intentional breeding of certain traits over others by humans.

Catastrophism

The theory that Earth's geology and biological history has been shaped by a series of sudden, short-lived, and violent events.

Gene Pool

The sum of all copies of all alleles at all loci in a population.

Echolocation

A biological sonar used by bats to detect objects by echolocation.

Geological Strata

Layers of sedimentary rock that provide historical information about Earth’s surface.

Common Ancestor

A shared ancestor from which two or more descendant species evolve.

Adaptive Traits

Characteristics of an organism that enhance its survival and reproductive success in a specific environment.

Founder Effect

A reduction in genetic variation when a small subset of a population establishes a new population.

Struggle for Existence

The competition among individuals for limited resources necessary for survival.

Convergent Evolution

The evolution of similar traits in distantly related species due to similar environmental pressures.

Divergent Evolution

The accumulation of differences between closely related species, leading to speciation.

Behavioral Isolation

When two populations are capable of interbreeding but have differences in courtship rituals or other behaviors.