Evolution and Speciation

Vocabulary flashcards covering key concepts from chapters 17, 18, and 19 related to evolution, natural selection, and speciation.

Natural Selection

Darwin's theory that explains how allele frequencies change over time through components like variation, inheritance, selection, and time.

Alleles

Different versions of genes that contribute to variations within a population.

Adaptations

Traits that enhance survival and reproduction in a specific environment.

Fitness

The ability of an organism to survive and reproduce in its environment.

Homologous Structures

Structures in different species that have a similar underlying anatomy, indicating common ancestry, but may have different functions.

Analogous Structures

Structures in different species that have similar functions but evolved independently and do not share a recent common ancestor.

Evolution

The change in the heritable characteristics of biological populations over successive generations.

Sources of Genetic Variation

Mutations and genetic recombination during sexual reproduction.

Directional Selection

A mode of natural selection in which an extreme phenotype is favored over other phenotypes, causing the allele frequency to shift over time in the direction of that phenotype.

Stabilizing Selection

A type of natural selection in which the population mean stabilizes on a particular non-extreme trait value.

Disruptive Selection

A mode of natural selection in which extreme values for a trait are favored over intermediate values.

Genetic Drift

Random changes in allele frequencies due to chance events, more significant in small populations.

Gene Flow

The transfer of genetic material from one population to another.

Speciation

When two populations can no longer interbreed and produce viable, fertile offspring.

Reproductive Isolation

Mechanisms that prevent different species from interbreeding.

Behavioral Isolation

Isolation due to differences in courtship rituals or other behaviors.

Geographic Isolation

Isolation due to physical barriers that prevent gene flow.

Temporal Isolation

Isolation due to differences in breeding seasons or times of day.

Cladograms and Phylogenetic Trees

Diagrams that show the evolutionary relationships among organisms.

Parsimony

The principle that the simplest explanation is the most likely.