Natural Selection

2. an accidental change in a gene or chromosome that leads to a new trait
7. Selection for those individuals with average phenotypes and against those with extreme phenotypes.
8. Selection against average phenotypes and for the extreme phenotypes.
10. Selection for one end of phenotypic range at the expense of another; population tends to change in that direction.
11. Chance changes in allele frequencies.
13. English natural scientist who formulated a theory of evolution by natural selection
14. group of organisms so similar to one another that they can reproduce and produce fertile offspring
15. having traits that allow survival and success in one's environment
16. The formation of a new species.

1. the struggle between members of a species for food and other resources needed for survival
3. any difference between individuals of the same species
4. disappearance of a species from all parts of its geographical range
5. the process by which individuals that are better adapted to their environment are more likely to survive and reproduce than less fit members of the same species.
6. a group of organisms so similar to one another that they can reproduce and produce fertile offspring
9. a trait that a species has that allows it to survive in its environment
12. to change over time