A number of comparisons of nucleotide sequences among ho...

Question

A number of comparisons of nucleotide sequences among hominids and rodents indicate that inbreeding may have occurred more often in hominid than in rodent ancestry. Bakewell et al. (2007. Proc. Nat. Acad. Sci. [USA] 104: 7489-7494) suggest that an ancient population bottleneck that left approximately 10,000 humans might have caused early humans to have a greater chance of genetic disease. Why would a population bottleneck influence the frequency of genetic disease?

Accepted Answer

Hi, everyone. Let's look at our next problem. Offspring of biologically related persons are subject to the possible effects of inbreeding such as congenital birth defects, inbreeding results in the phenotype IQ expression of deleterious recessive alleles within a population. As a result. First generation inbred individuals show physical and health defects. Some of the defects include and then we've got our answer choices here. Um When we look through them, we see different combinations of um effects on fertility, cardiovascular risks, genetic disorders and in mortality. Well, we're talking about how inbreeding increases, deleterious recessive alleles. So we're looking for aliens that have harmful effects. So we can kind of zoom in on our answer by the idea that we're looking for basically bad results of all these things. So we'd be wanting to look for in terms of fertility effects. We want to look for reduced fertility which allows us to eliminate choice A which has increased fertility and breeding would not lead to increased fertility. Um The next is cardiovascular risks. Again, these deleterious risk alleles cause can cause increased cardiovascular risks. So since choice C has reduced cardiovascular risk will eliminate choice C down to B and D next would be genetic disorders, obviously inbreeding. Um definitely leads to a higher risk of in higher risk of genetic disorders. So we look for increased genetic disorders. Both B and D have that and finally, infant mortality because of the greater likelihood of various deleterious recessive valuables, um It does increase infant mortality. So you'd expect to see higher infant mortality. Choice B has low infant mortality. So we can eliminate choice B and we're left with Choice D reduced fertility, increased cardiovascular risks, increased genetic disorders and high infant mortality. So again, that would be defects seen in first generation inbred individuals. Choice D being our answer. See you in the next video.

Key Concepts

Population Bottleneck

Genetic Drift

Inbreeding Depression

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