| A | B |
|---|
| variation | any difference between individuals of the same species |
| adaptation | a trait that helps an organism survive and reproduce |
| environmental pressure | the factors that cause organisms to compete for resources |
| selective breeding | usually used by farmers and others |
| species | a group of similar organisms on Earth |
| breeders | choose which mates to breed |
| natural selection | survival of the fittest |
| fossil | the preserved remains of an organism that lived in the past |
| evolution | the gradual change in a species over time |
| scientific theory | a well-tested concept that explains wide range of observations |
