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).