Fossil
A preserved remain or impression of an organism that lived in the past.
variation
Any inherited difference between individuals of the same species.
adaptation
An inherited trait that helps an organism survive and reproduce
mutation
A change in the DNA of an organism.
homologous structures
Structures that are similar in different related species that have been inherited from a common ancestor.
species
A group of similar organisms that can mate and produce fertile offspring.
common ancestor
The shared ancestor of new, different species that arose from one population
competition
occurs when two organisms try to acquire or use the same resource
selective pressure
environmental conditions that select for certain characteristics of individuals and select against other characteristics
population
A group of individuals that belong to the same species and live in the same area
evolution
A change in a population of organisms over time. A change in the gene frequency of a population over time.
natural selection
A process where individuals with certain inherited traits are more likely to survive environmental pressures and reproduce than those that don't have those traits. AKA "Survival of the Fittest".
vestigial structures
Structures that are inherited from ancestors but have lost much or all of their original function. They show that the organism is related to the ancestor and to organisms that are alive today with a functioning structure.
geographic isolation
Form of isolation in which two populations are separated physically by geographic barriers such as rivers, mountains, or stretches of water. Over time, the two populations can become different species.
reproductive isolation
Members of different species refuse to mate and reproduce. Example; Anole lizards have been separated a long time and have become two different species. If the two species are brought back together they will not mate with each other because they are so di
comparative biochemistry
Comparing the DNA, amino acids or proteins of organisms. The fewer differences that there are in these structures, the more closely related they are.
Fitness
The ability to survive and reproduce more than others, in a certain environment.
Hybrid
An offspring resulting from the cross between parents of different species that is sterile or infertile. THIS IS NOT A NEW SPECIES. Example: A horse and a donkey make a mule. THE MULE IS A HYBRID, NOT A NEW SPECIES.