BIO 370 Lecture Notes - Lecture 16: Population Bottleneck, Allele Frequency, Genetic Drift
Demography, Biogeography, and Drift
Even very large populations can go through rough periods where population size becomes
small.
When populations become very small, even for a short time, allele frequencies can change
dramatically. What is this called?
Population bottleneck.
Northern elephant seals underwent a drastic reduction in population size in the late 1800s.
Roughly 10- suriors gae rise to today’s populatio of ell oer , idiiduals.
Southern elephant seals did not experience a comparable bottleneck. What does the following
graph of enzyme electrophoresis data show?
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enzyme electrophoresis to look for molecular variation in the structure of 21 different
proteins—and by this assay found no variation whatsoever
Always low in genetic diversity but bottleneck caused it to become even lower.
Low variation in northern elephant seals
Low variation in northern elephant seals: DNA sequence data.
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?
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find more resources at oneclass.com
Document Summary
Even very large populations can go through rough periods where population size becomes small. When populations become very small, even for a short time, allele frequencies can change dramatically. Northern elephant seals underwent a drastic reduction in population size in the late 1800s. Roughly 10-(cid:1006)(cid:1004) sur(cid:448)i(cid:448)ors ga(cid:448)e rise to today"s populatio(cid:374) of (cid:449)ell o(cid:448)er (cid:1005)(cid:1004)(cid:1004),(cid:1004)(cid:1004)(cid:1004) i(cid:374)di(cid:448)iduals. Southern elephant seals did not experience a comparable bottleneck. What does the following graph of enzyme electrophoresis data show? enzyme electrophoresis to look for molecular variation in the structure of 21 different proteins and by this assay found no variation whatsoever. Always low in genetic diversity but bottleneck caused it to become even lower. Low variation in northern elephant seals: dna sequence data. 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.
