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10 Cards in this Set
- Front
- Back
adding migration to HWE
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•homogenizing evolutionary force across populations; therefore often preventing divergence of populations
•FST- 0 (no population differentiation) to 1 (great genetic differentiation between pops) |
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Water snakes of Lake Erie -example of migration effects
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-migration and natural selection working against each other
-have two different color morphs of same species -have mostly banded snakes on islands -mostly unbanded on islands -migration tends to move from mainland to islands -islands have selective force favoring unbanded morphs |
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selection and mutation effects on HWE
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-selection can push traits one way or the other-directional and often reduces genetic diversity-shifts curve, and makes it smaller
-MHC [? histamine complex] selection an example of selection that increases diversity -selection probably causes more differentiation between isolated populations than homogenization but it depends on the selective pressure -mutation increases genetic diversity but start at very low levels-causes isolated populations to differentiate |
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Models of Gene Flow
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1. Island model
2. Stepping-stone model 3. Isolation by distance model |
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Island model
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multiple populations connected with each other , individuals from one population move to other populations -might see in a more homogeneous area with no major barriers
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Stepping stone model
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-have to go thru populations sequentially (must go thru one to get to another) -might see in a chain of islands
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Isolation by distance model
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- (independent variable on x axis-distance, dependent variable on y-axis-genetic distance), would expect a positive linear relationship between genetic distance and geographic distance if population fits this model
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Estimates of Gene Flow:
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1. Direct estimates
2. Indirect estimates |
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Direct estimates
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-trying to follow individuals and see if they contribute genetic material to next generation-difficult to collect-methods like radiotelemetry, satellite transmitters, GIS-can overlay movements on topography-don’t give much info about reproduction
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Indirect estimates
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-assignment test, evidence of gene flow thru the alleles
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