Biology Ch.16

4. This takes place when individuals at one end of the curve have higher fitness than individuals in the middle or at the other end.
6. The _____ of an allele is the number of times that the allele occurs in a gene pool, compared with the number of times other alleles for the same gene occur.
11. The situation in which allele frequencies remain constant.
12. Traits that are controlled by two or more genes.
13. Change in allele frequencies as a result of the migration of a small subgroup of a small population.
14. The separation of species or populations so that they cannot interbreed and produce fertile offspring.
15. Consists of all genes, including all the different alleles, that are present in a population.
16. The form of reproductive isolation in which two populations reproduce at different times.

1. trait A trait that is controlled by a single gene that has two alleles.
2. Random change in allele frequencies that occurs in small populations.
3. This principle states that allele frequencies in a population will remain constant unless one or more factors cause those frequencies to change.
5. The form of reproductive isolation in which two populations have differences in courtship rituals or other types of behavior that prevent them from interbreeding.
7. The formation of new species.
8. This takes place when individuals at the at the upper and lower ends of the curve have higher fitness than the individuals near the middle.
9. This takes place when individuals near the center of the curve have higher fitness than individuals at either end of the curve.
10. The form of reproductive isolation in which two populations are separated physically by geographic barriers such as rivers, mountains, or stretches of water