Speciation and Gene Flow

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Speciation and Gene Flow
2013-09-24 20:05:08
Biology GRE

Biology GRE
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  1. Natural Selection according to Darwin
    • Genetic Varriability exists in population
    • There is an overproduction of offspring for limited resources
    • There is competition among offspring for limited resources
    • Not all offspring will survive long enough to reproduce
  2. Isolation
    • One Species can not reach another species either geographically or reproductively
    • Genes from one pool cannot mis with genes from another population
    • Can happen via emigration or allele out of original gene pool, new genes may be selected in new area that are different from original pool
  3. Speciation
    • Formation of new species when one pool of certain species changes over time in ways that are distinct from changes in other other population of same species
    • Enough Changes in genetic material to eliminate interbreeding
  4. Geographic Isolation
    Can occur slowly (Mountain ranges form) or suddenly (earthquakes)
  5. Sympatric Isolation
    • Occurs together
    • Group of organism becomes reproductively isolated within the parent population
    • Happens frequently in plants, whose reproduction leads to polyploid offspring who cannot reproduce with parent population but are still viable
  6. Autopolyploid
    Act of becoming polyploid via self fertilization
  7. Allopolyploid
    • The act of becoming polyploid by combining your chromosomes with another species
    • Two similar genetic plats mate and from hybrid
  8. Genetic Drift
    • Major Role in evolution
    • The smaller a population the greater effect small changes in allele frequency haveĀ 
    • Describes the changes that occur in a populations gene pool from generation to generation due to random chance
  9. Founder Effect
    • When smalle group of individuals colonizes an island or isolated habitat
    • New population can diverge greatly from original population that small group originally came from
    • Genetic drift is influences by the number of offspring, more offspring means they are more similar to their parents
  10. Bottleneck effect
    • Relatively sudden narrowing of genetic diversity
    • Happens when a portions of population is wiped out (natural disaster)
    • Alleles that survive are not naturally selected
    • Small population that remains can then vary greatly from original population vis genetic drift
    • Genetic drift can result in unbalanced polymorphisms, population can become homozygous and eliminate the chance of the other homo in the future
  11. Gene Flow
    Movement of genes from one population to another