1							2																	3
									4
					5																		6
7
								8
9
10
		11
12
	13
							14
						15
														16

Across 1. Occurs when two populations are capable of interbreeding but have differences in courtship rituals or other reproductive strategies. 4. 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. 5. Allele frequencies change as a result of the mirgration of a small subgroup of a population 7. Two populations are separated by geographic barriers such as rivers, mountains, or bodies of water 8. A trait controlled by a single gene that has two alleles 9. When individuals at the upper and lower ends of the curve have higher fitness than individuals near the middle. 10. Two or more species reproduce at different times. 11. consists of all genes, including all the different alleles, that are present in a population 12. When individuals at one end of ther curve have a higher fitness than individuals in the middle or at the other end. 13. States that allele frequencies in a population will remain constant unless one or more factors cause those frequencies to change. 14. Random change in allele frequency 15. Allele frequencies remain constant 16. Changes which lead to the formation of new species

Down 2. When members of two populations cannot interbreed and produce fertile offspring. 3. A trait controlled by two or more genes 6. When individuals near thr center of the curve have a higher fitness than individuals at either end of the curve