Ch 18 Vocabulary

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Across
  1. 3. situation in which allele frequencies in a population remain the same
  2. 5. trait controlled by two or more genes
  3. 7. natural selection in which individuals at the upper and lower ends of the curve have higher fitness than individuals near the middle of the curve
  4. 13. random changes in allele frequency caused by a series of chance occurrences that cause an allele to become more or less common in population
  5. 14. isolation form of reproductive isolation in which two populations develop differences in courtship rituals or other behaviors that prevent them from breeding
  6. 15. separation of a species or population so that they can no longer interbreed and evolve into two separate species
  7. 17. change in allele frequencies as a result of the immigration of small subgroup of a population
  8. 19. a change in allele frequency following a dramatic reduction in the size of a population
  9. 20. method used by researches that uses mutation rates in DNA to estimate the length of time two species have been evolving
  10. 21. isolation form of reproductive isolation in which two or more species reproduce at different times
Down
  1. 1. form of natural selection in which individuals at one end of a distribution curve have a higher fitness than individuals in the middle or at the other end of the curve
  2. 2. trait controlled by one gene that has two alleles
  3. 4. principle that states that allele frequencies in a population remain constant unless one or more factors cause those frequencies
  4. 6. isolation form of reproductive isolation in which 2 populations are separated by geographic rivers mountains or bodies of water leading to the formation of two separate subspecies
  5. 8. form of natural selection in which individuals near the center of a distribution curve have higher fitness than individuals at either end of the curve
  6. 9. a group of similar organisms that can breed and produce fertile offsprings
  7. 10. when individuals select mates based on heritable traits
  8. 11. number of times that an allele occurs in a gene pool as a percentage of the total occurrence of all alleles for the gene in the gene pool
  9. 12. all the genes, including all alleles for each gene, that are present in population
  10. 16. the movement of genes into or out of a population
  11. 18. form of a new species