Genetic drift causes divergence between populations

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Genetic Drift Causes Divergence Between Populations over Time
The researchers reasoned that in the absence of gene flow, genetic drift should strongly influence the patterns of diversity at these loci. What did they expect to see? Genetic Drift Causes Divergence Between Populations over Time Predictions: 1. Drift is expected to operate more strongly—and cause more loss of variation—in smaller populations. Thus, the smaller lizard populations on smaller islands would be expected to have FEWER micro satellite alleles than larger populations on larger islands
Demography, Biogeography, and Drift
Even very large populations can go through rough periods where population size becomes small. Demography, Biogeography, and Drift
When populations become very small, even for a short time, allele frequencies can change dramatically. What is this called? Demography, Biogeography, and Drift Genetic Drift
When populations become very small, even for a short time, allele frequencies can change dramatically. What is this called? Demography, Biogeography, and Drift Bottleneck
What does this show? What does this show? What does this show?
What does this show? What does this show?
What does this show?
Northern elephant seals underwent a drastic reduction in population size in the late 1800s. Roughly 10-20 survivors gave rise to today’s population of well over 100,000 individuals. Demography, Biogeography, and Drift
Southern elephant seals did not experience a comparable bottleneck. What does the following graph of enzyme electrophoresis data show? Demography, Biogeography, and Drift Support the theoretical prediction that a tight bottleneck should greatly reduce the genetic variation within a population
What does the following graph of DNA data show? Demography, Biogeography, and Drift Low variation in northern elephant selas. 3 di ff erent highly variable loci reveal much greater variation in southern elephant seal populations than in northern elephant seal populations
The question remained, however, if the bottleneck was the cause of the low level of heterozygosity among northern elephant seals. It was also possible that the population had unusually low levels of variation even before the bottleneck. Demography, Biogeography, and Drift
The question remained, however, if the bottleneck was the cause of the low level of heterozygosity among northern elephant seals. It was also possible that the population had unusually low levels of variation even before the bottleneck. How did they figure this out? Demography, Biogeography, and Drift They extracted mitochondrial DNA from bone and dried skin of animal samples taken before, during, and after the tightest part of the bottleneck. Post bottleneck= 2 genotypes Before= 4 genotypes Bottleneck was coincident with, and the cause o ff , the severe reduction in heterozygosity
The question remained, however, if the bottleneck was the cause of the low level of heterozygosity among northern elephant seals.

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