The Theory of Evolution

fossils

preserved remains of, or traces of ancient organisms

radiometric dating

a method of dating geological or archeological specimens by determining the relative proportions of particular radioactive isotopes present in a sample

edosymbiotic theory

complex organelles originated from prokaryotic cells that were engulfed to form a symbiotic relationship with ancestrial eukaryotic cell

evolution

heritable change in the characteristics within a population from one generation to the next

descent with modification

every organism comes about by reproduction and can change over time

natural selection

process by which individuals with certain inherited traits tend to survive and reproduce at higher rates because of those traits

evolution happens because of _________

natural selection

overproduction

a species produces more offspring than can survive to maturity

genetic variation

every individual has different traits leading to variation among populations

struggle to survive

individuals must compete to survive and reproduce

adaptation

trait that makes an individual successful in its environment

differential reproduction

organisms with the best adaptations are more likely to survive and reproduce

fitness

measure of how well an organism can survive and reproduce

stabilizing selection

a type of natural selection in which genetic diversity decreases as the population stabilizes on a particular trait

disruptive selection

individuals with extreme variations of a trait have greater fitness than individuals with the average form of the trait

directional selection

individuals that display a more extreme version of a trait have greater fitness than individuals with an average form of the trait

gradualism

variation is gradual in nature and happens steadily over time

punctuated equilibrium

equilibrium is interrupted by brief periods of rapid change

acclimation

short-term process, physiological changes take place in a lifetime

background extinction

normal, ongoing extinction

mass extinction

large number of species become extinct in a relatively short amount of time

biogeography

study of where organisms live now and where they and their ancestors lived in the past

homologous structures

structures that are shared between different but related species

analogous structures

structures that are similar in function but among species that do not share a common ancestor

Ex: wings of a butterfly or bird

vestigial structures

structures that seem to serve no function but resemble functional structures in related organisms

Ex: a human appendix