Unit 3 Vocab
Microevolution- evolutionary changes that take place over long periods of time through natural selection, but do
not involve the formation of new species (changes within a species)
Macroevolution- large-scale evolutionary changes that take place over long periods of time (involves the
formation of new species)
Natural selection- Natural selection is the gradual, nonrandom process by which biological traits become either
more or less common in a population as a function of differential reproduction of their bearers. It is a key mechanism
of evolution.
Mutation- a change or alteration in form or qualities
Adaptation- a trait that helps an organism survive and reproduce
Fitness- ability of an organism to survive and reproduce in its environment
Reproductive isolation- separation of species or populations so that they cannot interbreed and produce fertile
offspring
Gradualism- The theory that evolution occurs slowly but steadily
Punctuated equilibrium-a theory of evolution holding that evolutionary change in the fossil record came in fits
and starts rather than in a steady process of slow change
Homologous structure-similar structure found in more than one species that share a common ancestor
Analogous structure-structures that do not have a common evolutionary origin but are similar in function
Vestigial structure-remnant of a structure that may have had an important function in a species' ancestors, but
has no clear function in the modern species
Phylogenic tree-A chart showing evolutionary relationships as determined by phylogenic systematics. It contains a
time component and implies ancestor-descendant relationships
Embryology-the branch of biology that studies the formation and early development of living organisms