Evolution

Adaptation

A trait that improves an organism's ability to survive and reproduce in its environment.

Adaptive Radiation

One species evolves into many different forms that live in different ways (e.g., Darwin’s finches).

Allele Frequency

How often an allele appears in a population’s gene pool.

Amino Acid Sequencing

Comparing protein sequences to find evolutionary relationships.

Analogous

Structures with similar function but different evolutionary origins (e.g., bird wing vs. insect wing).

Artificial Selection

Humans breed organisms for desired traits.

Biogeography

Study of species distribution across the planet.

Bottleneck Effect

Sharp reduction in population size, changing allele frequencies.

Coevolution

Two species evolve in response to changes in each other.

Convergent Evolution

Different species evolve similar traits due to similar environments.

Darwin

Proposed natural selection as the mechanism for evolution.

Directional Selection

Favors one extreme phenotype, shifting population traits.

Disruptive Selection

Favors both extreme phenotypes over intermediate ones.

Divergent Evolution

One species evolves into multiple different species.

Embryology

Study of embryos; similarities suggest common ancestry.

Epoch

Smallest time unit in geological time (part of a period).

Era

Large division of geologic time (e.g., Mesozoic Era).

Evolution

Change in species over time through genetic variation and selection.

Extinction

When a species completely dies out.

Fitness

An organism’s ability to survive and reproduce.

Fossils (Types)

Examples: mold, cast, preserved, trace, petrified.

Founder Effect

Genetic differences in a small group that starts a new population.

Genetic Drift

Random change in allele frequency in small populations.

Genetic Equilibrium

When allele frequencies in a population do not change (Hardy-Weinberg).

Gradualism

Slow and steady evolutionary change.

Homologous

Structures with similar origin but different function (e.g., human arm and whale flipper).

Isolating Mechanisms

Barriers that prevent species from interbreeding (e.g., behavioral, temporal, geographical).

Lamarck

Suggested organisms change by using or not using traits (disproven).

Macroevolution

Large-scale evolutionary changes over long time periods.

Microevolution

Small changes in allele frequency within a population.

Migration (Gene Flow)

Movement of alleles between populations.

Morphology

Study of the form and structure of organisms.

Mutations

Changes in DNA; source of genetic variation.

Natural Selection

Process where better-adapted organisms survive and reproduce.

Nonrandom Mating

Mating based on traits, affecting allele frequencies.

Period

Division of geologic time shorter than an era.

Phenotype Frequency

Proportion of individuals with a specific physical trait.

Phylogeny

Evolutionary history and relationships among species.

Population Genetics

Study of allele frequency changes in populations.

Punctuated Equilibrium

Rapid bursts of change followed by stability.

Relative Positioning

Determining fossil age based on layer location.

Speciation

Formation of new species.

Stabilizing Selection

Favors average traits and reduces variation.

Theory of Evolution

Scientific explanation for the diversity of life through evolution.

Universal Ancestor

The hypothetical common ancestor of all life.

Variation

Differences among individuals in a population.

Vestigial

Structures with no current function but ancestral past (e.g., human appendix).