Natural selection

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Across
  1. 2. Mechanism of evolution developed by darwin, based on four ideas excess reproduction, variations, inheritance, and the advantages of specific traits in an environment
  2. 3. The formation of new species in populations that are geographically isolated from one another.
  3. 4. process in which individuals with average traits are removed creating two populations with extreme traits
  4. 6. new feature that had not appeared in common ancestors
  5. 7. change in the frequency of a trait based on the ability to attract a mate
  6. 8. allelic frequencies in populations stay the same unless they are affected by a factor that causes change
  7. 13. mechanisms that operate after fertilization to ensure that the resulting hybrid remains infertile.
  8. 15. most common form of natural selection in which organisms with extreme expressions of a trait are removed
  9. 16. shift of a population toward an extreme version of a beneficial trait
  10. 17. can occur when a small population settles in an area separated from the rest of the population and interbreeds
  11. 18. selection by humans for breeding of useful traits from the natural variation among different organisms
  12. 21. study of the distribution of plants and animals on earth
  13. 23. morphological adaptation in which one species evolves to resemble another species for protection
  14. 24. more-primitive characteristic that appeared in common ancestors
  15. 25. A 'leftover' structure. It is non functional and indicates shared ancestry
  16. 26. hereditary changes in groups of living organisms over time
  17. 27. A species evolves into a new species without a physical barrier.
  18. 28. The ability of an individual to survive and reproduce in its specific environment
Down
  1. 1. theory that evolution occurs with relatively sudden periods of speciation followed by long periods of stability
  2. 5. same function but different structure that is not inherited from a common ancestor
  3. 9. Prevents reproduction by making fertilization unlikely through geographical, ecological, behavioral, temporal (time) or other differences.
  4. 10. similar structure inherited from a common ancestor
  5. 11. organism's early prebirth stage of development
  6. 12. diversification of a species into a number of different species over a relatively short time span
  7. 14. A change in the gene pool of a population due to chance. Changes the frequency of alleles.
  8. 19. process in which a large population declines in number and rebounds with a different allele frequency.
  9. 20. theory that evolution occurs in gradual steps over time
  10. 22. morphological adaptations that allow organisms to blend into their surroundings