How can we help?

You can also find more resources in our Help Center.

Evolution Vocab

STUDY
PLAY
species
group of organisms so similar to one another that they can breed and produce fertile offspring
fossil
trace of an organism from the past
catastrophism
theory that states that natural disasters such as floods and volcanic eruptions shaped Earth's landforms and caused the extinction of some species (Cuvier)
gradualism
principle that states that the changes in landforms result from slow changes over a long period of time (Hutton)
uniformitarianism
theory that states that the geologic processes that shape Earth are uniform through time (Lyell)
variation
differences in physical traits of an individual from the group to which it belongs
adaptation
inherited trait that is selected over time because it allows organisms to better survive in their environment
artificial selection
process by which humans modify a species by breeding it for certain traits
population
all of the individuals of a species that live in the same area
fitness
measure of an organism's ability to survice and produce offspring relative to other members of a population
biogeography
the study of the distribution of organisms around the world
homologous structure
body part that is similar in structure on different organisms, but performs different functions (ex. limbs of humans and bat wings)
analogous structure
body part that is similar in function as a body part of another organism, but is structurally different (ex. moth wings and bird wings)
vestigial structure
remnants of an organ or structure that functioned in an earlier ancestor (ex. wisdom teeth or tail bones)
paleontology
study of fossils or extinct organisms
gene pool
collection of alleles found in all of the individuals of a population
allele frequency
proportion of one allele, compared with all the alleles for that trait, in the gene pool
microevolution
observable change in the allele frequency of a population over a few generations
directional selection
pathway of natural selection in which one uncommon phenotype is selected over a more common phenotype
stabilizing selection
pathway of natural selection in which intermediate phenotypes are selected over phenotypes at both extremes
disruptive selection
pathway of natural selection in which two opposite, but equally uncommon, phenotypes are selected over the most common phenotype
gene flow
physical movement of alleles from one population to another
genetic drift
change in allele frequencies due to chance alone, occurring most commonly in small populations
bottleneck effect
genetic drift from an event that drastically reduces the size of a population
founder effect
genetic drift that occurs after a small number of individuals colonize a new area
sexual selection
selection in which certain traits enhance mating success, traits are, therefore, passed on to offspring
reproductive isolation
finals stage in speciation, in which members of isolated populations are either no longer able to mate or mo longer able to produce viable offspring
behavioral isolation
isolation between populations due to differences in courtship or mating behavior
geographic isolation
isolation between populations due to physical barriers
temporal isolation
isolation between populations due to barriers related to time, such as differences in mating periods or differences in the time of day that individuals are most active
convergent evolution
evolution toward similar characteristics in unrelated species, resulting from adaptations to similar environmental conditions
divergent evolution
evolution of one or more closely related species into different species; resulting from adaptations to different environmental conditions
coevolution
process in which two or more species evolve in response to changes in each other
punctuated equilibrium
theory that states that speciation occurs suddenly and rapidly followed by long periods of little evolutionary change
speciation
evolution of two or more species from ome ancestral species