Honors Biology - Evolution Vocabulary

Flashcards for Honors Biology 2025: Evolution, covering vocabulary related to allele frequency, genetic drift, natural selection, speciation, and evidence for evolution.

Allele Frequency

The proportion of a specific allele within a population's gene pool.

Gene Pool

The total collection of genes in a population at any one time.

Mutation

A change in the nucleotide sequence of DNA.

Adaptations

Inherited traits that enhance survival and reproduction in a specific environment.

Speciation

The process by which new biological species arise.

Genetic Drift

Random changes in allele frequencies in a population, especially significant in small populations.

Bottleneck Effect

A sharp reduction in the size of a population due to environmental events or human activities, which reduces the genetic diversity.

Founder Effect

The reduced genetic diversity that results when a population is descended from a small number of colonizing ancestors.

Gene Flow

The transfer of genetic variation from one population to another.

Sexual Selection

A form of natural selection in which individuals with certain inherited characteristics are more likely than other individuals to obtain mates.

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.

Reproductive Isolation

The existence of biological factors (barriers) that impede members of two species from interbreeding and producing viable, fertile offspring.

Prezygotic Isolation

A barrier that blocks fertilization from ever occurring. Includes habitat isolation, temporal isolation, behavioral isolation, and mechanical isolation.

Postzygotic Isolation

A barrier that occurs after hybrid zygotes are formed. Includes reduced hybrid viability, reduced hybrid fertility, and hybrid breakdown.

Temporal Isolation

A prezygotic reproductive barrier where two species breed during different times of day or year.

Behavioral Isolation

A prezygotic reproductive barrier where two species have different courtship rituals that signal mate recognition.

Geographical Isolation

A prezygotic reproductive barrier where two species live in different geographic areas and do not interact.

Mechanical Incompatibility

A prezygotic reproductive barrier where two species have incompatible reproductive parts.

Hybrid Inviability/Infertility

Postzygotic barrier where hybrid offspring either cannot survive or cannot reproduce.

Extinction

The state or process of a species, family, or larger group being or becoming extinct.

Fossils

The preserved remains or traces of ancient organisms.

Relative Dating

A method of determining the age of fossils by comparing their placement with that of fossils in other layers of rock.

Radioactive Dating

A method for determining the age of fossils and rocks using the rate of decay of radioactive isotopes.

Embryology

The study of the development of an embryo and fetus.

Homologous Structures

Structures in different species that are similar because of common ancestry.

Analogous Structures

Structures that do not have a common evolutionary origin but are similar in function.

Vestigial Structures

A structure in an organism that has lost all or most of its original function in the course of evolution.

Comparative Biochemistry

The study of the similarities and differences in the biochemical composition of organisms.

Natural Selection

The process whereby organisms better adapted to their environment tend to survive and produce more offspring.

Fitness

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

Heritability

The ability of a trait to be passed from one generation to the next.

Descent with Modification

The passing on of traits from parent organisms to their offspring; species change over time.

Cladogram/Phylogenetic Tree

A branching diagram showing the cladistic relationships between a number of species.