17 pt 2.txt

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17 pt 2.txt
2013-08-05 23:45:57

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  1. How can one lineage split into two isolated species?
    Dobzhansky-muller model and chromosomal rearrangements
  2. How can gene flow be interrupted?
    Allopatric and sympatric speciation
  3. What is an allopatric speciation?
    When populations are separated by a physical or geographic barrier;
  4. How can allopatric barriers form?
    When continents drift, sea levels rise or fall, and glaciers form or melt, or climates change and founder events
  5. What is adaptive radiation?
    When a species reaches a new place and it undergoes multiple speciation events
  6. What is sympatric speciation?
    Speciation without physical isolation
  7. How can sympatric speciation happen?
    Disruptive selection and/or assortative mating; basically, anything that leads to a reproductive subdivision within a population
  8. What is polyploidy?
    Duplication of sets of chromosomes within individuals; speciation occurs mostly by this kind of isolation.
  9. What is autopolyploidy?
    Chromosome duplication in a single species
  10. What is allopolyploidy?
    Combining of chromosomes within two different species
  11. Why is sympatric speciation by polyploidy more common in plants?
    Because many can self-fertilize
  12. Finish the statement: polyploidy speciation also occurs (rarely) in __________.
  13. What must be maintained for speciation to occur?
    Reproductive speciation
  14. What is an incipient species?
    Populations that are IN THE PROCESS of diverging but still have the potential to interbreed
  15. When incipient species come back into contact, hybridization occurs. What happens to hbrids?
    They can be less fit, selection favors parents that DON’T hybridize, so this leads in a reinforcement of isolating mechanisms. If the offspring is not less fit, then the populations may rejoin and morph back into a single species over time
  16. What are postzygotic isolating mechanisms?
    Mechanisms that reduce the fitness of hybrid offspring
  17. What are prezygotic isolating mechanisms?
    Mechanisms that prevent hybridization from occurring.
  18. What are some methods of postzygotic isolating mechanisms?
    Reduced genetic compatibility, low hybrid zygote viability, low hybrid adult viability, hybrid infertility.
  19. What are the categories of prezygotic isolating, mechanisms?
    Mechanical, temporal isolation, behavioral, habitat, gametic.
  20. How do mechanical isolations work?
    They create differences in sizes and shapes of reproductive organs
  21. How do temporal isolations work?
    Have species breed at different times of the year or different times of day.
  22. How does behavioral isolation work?
    Individuals reject or fail to recognize mating behaviors of other species
  23. How does gametic isolation work?
    Sperm and eggs of different species will not fuse. This is important for aquatic animals
  24. What are hybrid zones?
    Areas where reproductive isolation is incomplete.