How can we help?

You can also find more resources in our Help Center.


a theory which states that all living things change over time; attempts to explain biodiversity
(biological evolution) pricess in which new species develop from preexisting species
(genetic evolution) a change in the allele frequencies of a population of organisms from generation to generation
a proposed explanation in evolutionary biology stating that new species arise from the result of slight modifications (mutations and resulting phenotypicchanges) over many generations.
natural selection
a process in nature in which organisms possesing certain inherited tratis are better able to survive and reproduce compared to others of their species. (Survival of the fittest)
punctuated eqilibrium
a proposed explanation in evolutionary biology stating that species are generally stable over long periods of time. Occasionally there are rapid changes that affect some species which can quickly result in new species
the study of an organism's evolutionary history
the preserved remains or traces of organisms that once lived on Earth
the branch of zoology studying tha early development of living things
homologous structure
a physical characteristic in different organisms that is similar because it was inherited from a common ancestor. (structures with a shared embryonic development)
Analogous structure
A physical structure, present in multiple species, that is similar in function but different in form and inheritance. (structures with a similar function but different embryonic development)
vestigial structure
a physical characteristic in organisms that appears to have lost its original function as a species has changed over time
the hardy-weinburg eqilibrium theory
a prinicpal stating that the genetic veriation in a population will remain constant from one generation to the next in the abscense of disturbing factors
allele frequency
the measure of the relative frequency of an allele at a genetic locus in a population; expressed as a proportion or percentage
genotypic frequency
the measure of the relative frequency of a genotype in a population; expressed as a proportion or percentage
a permanent transmissible change of genetic material (e.g. chromosomal mutations and gene mutations)
migration (genetics)
the permanent movement of genes into or out of a population resulting in a change in allele frquencies
genetic drift
a change in the allel frequency of a population as a result of chance events rather than natural selection
founder effect
a decrease in genetic variation caused by the formation of a new popualtion by a small number of individuals from a larger population
isolating mechanisms
features of behavior, morphology, or genetics which serve to prevent mating or breeding between two different species
prezygotic barriers
mechanisms which prevent fertilization to take place
postzygotic barriers
mechanisms which prevent hybrid viability after fertilization takes place
a precess typically caused by the genetic isolation from a main population resulting in a new genetically distinct species
the lowest taxonomic level of biological classification consisting of organisms capable of reproduction that results in fertile viable offspring
adaptive radiation
a process of evolution that results in several species deriving from a common ancestor; increases biodiversity
convergant evolution
a process of evolution that results in unrelated organisms developing similar characteristics due to a shared environment
a term that typically describes a species that no longer has any known living individuals