Evolution
change in a kind of organism over times: process by which modern organisms have descended from ancient organisms.
Theory
well-test explanation that unifies a board range of observations.
Fossil
preserved remains or evidence of an ancient organism.
Artificial selection
selection by human for breeding of useful traits from the natural variation among different organisms.
Struggle for existence
competition among members of a species for food, living space, and the other necessities of life.
Fitness
ability of an organism to survive and reproduce in its environment.
Adaptation
inherited characteristic that increases an organism chance of survival.
Survival of the fittest
process by which individuals that are better suited to their environment survive and reproduce most successfully; ALSO CALLED NATURAL SELECTION.
Descent with modification
principle that each living species has descended, with changes, from other species over time.
Common descent
principle that all living things derived from common ancestors.
Homologuous structure
structures that have different mature forms in different organisms but develop from the same embryonic tissues.
Vestigial organ
organ that serves no useful function in an organism.