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Evolution (population changes (genetic drift- events cause allele…
Evolution
population changes
genetic drift- events cause allele frequencies to fluctuate unpredictably from generation to generation
Founder effect- when a few individuals become isolated from a larger population, new group establishes population whose genes differs from the source population
Bottleneck effect- server drop in population because a change in the environment, leads to less genetic variation
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Stabilization selection- removes extremes, favors intermediate types
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Intersexual selection- mate choise, female picks male
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evolution of populations
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Genetic variation are differences among individuals in the composition of their genes or other DNA sequences, makes evolution possible
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A population is a group of individuals of the same species that live in the same area and interbreed, producing fertile off springs.
A populations gene pool consist of all the copies of every type of allele at every locus in all members of the population.
Hardy-weinberg equation used to see what percent of a population has a certain gene or are carriers of a gene.
1.No mutations, 2. no gene flow in population,3.population must be very large,4. mating must be random,5. no natural selection, 6.allele is not sex-linked
Meiosis- sex cells, mitosis- cell replication
origins of species
A Biological species is a group of populations whose individuals may interbreed and produce viable, fertile offspring with each other but not with members of other species
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Postzygotic barriers
- reduce hybrid viability- most offspring die
- reduce-hybrid fertility- sterilize offspring's
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Geographic isolation- when a part of the species gets geographically separated from their group and start a new population
Allopatric speciation- a population forms a new species while geographically isolated from its parent population
Sympatric specification- a subset of a population forms a new species without geographic separation.
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