Darwin's Theories

theory of evolution

organisms change and develop over time to adapt an increase rate of survival

common ancestor

the shared ancestor of new, different species that arose from one population

struggle for existence

competition among members of a species for food, living space, and the other necessities of life

differential reproductive success

phenomenon in which individuals with adaptive genetic traits produce more living offspring than do individuals without such traits

acquired traits

characteristics or behavior not genetic or inherited

inheritance of acquired characteristics

the hypothesis that organisms' bodies change during their lifetimes by use and disuse and that these changes are inherited by their offspring

traits

a characteristic that an organism can pass on to its offspring through its genes

artificial selection

selection by humans for breeding of useful traits from the natural variation among different organisms

natural selection

the principle that, among the range of inherited trait variations, those contributing to reproduction and survival will most likely be passed on to succeeding generations

adaptation

inherited characteristic that increases an organism's chance of survival

survival of the fittest

a natural process resulting in the evolution of organisms best adapted to the environment

biological fitness

a measure of the ability to survive and reproduce relative to other members of the population

descent with modification

principle that each living species has descended, with changes, from other species over time

principle of common descent

the idea that all organisms share an ancient common ancestor