It is known that diversity of neutral loci can be reduced due to adjacent loci under selection (i.e. “linked selection”). On the other hand, it has been hypothesized that linked selection might slow loss of neutral genetic diversity in small populations. This phenomenon has been termed associative overdominance (AOD). However, whether AOD is a plausible explanation for the maintenance of genetic diversity in small populations is still an open question. An affirmative answer to this question would mean that conclusions based on genetic measures of genetic diversity and divergence could potentially be biased in the cases when they are most needed: the conservation of small, and usually endangered, natural populations.
We investigated whether AOD could explain the lower than expected results of genetic divergence of a dispersal experiment. The experiment consisted of 36 pairs of populations of Drosophila melanogaster with known effective population size and dispersal rate. When comparing theoretical expectations against the experiment results, we found that measures of genetic divergence (Fst) were downwards biased on average by 65%. We used agent-based simulations to investigate whether the effective number of recombination events were negatively correlated with the degree of bias. We also investigated whether neutral loci located in regions with a higher number of exons showed larger bias. We used our results to assess the presumed mechanisms by which AOD might affect genetic diversity: the interplay between low recombination rates and selection in small populations.
We argue that the interplay between low recombination rates and selection influences neutral genetic diversity. Our research highlights the importance of performing research that focuses on the adjustment of neutral theoretical models by the roles played by genome structure and genetic interactions, such as selection and recombination, which will ultimately allow us to better inform conservation efforts.
It is known that diversity of neutral loci can be reduced due to adjacent loci under selection (i.e. “linked selection”). On the other hand, it has been hypothesized that linked selection might slow loss of neutral genetic diversity in small populations. This phenomenon has been termed associative overdominance (AOD). However, whether AOD is a plausible explanation for the maintenance of genetic diversity in small populations is still an open question. An affirmative answer to this question would mean that conclusions based on genetic measures of genetic diversity and divergence could potentially be biased in the cases when they are most needed: the conservation of small, and usually endangered, natural populations.
We investigated whether AOD could explain the lower than expected results of genetic divergence of a dispersal experiment. The experiment consisted of 36 pairs of populations of Drosophila melanogaster with known effective population size and dispersal rate. When comparing theoretical expectations against the experiment results, we found that measures of genetic divergence (Fst) were downwards biased on average by 65%. We used agent-based simulations to investigate whether the effective number of recombination events were negatively correlated with the degree of bias. We also investigated whether neutral loci located in regions with a higher number of exons showed larger bias. We used our results to assess the presumed mechanisms by which AOD might affect genetic diversity: the interplay between low recombination rates and selection in small populations.
We argue that the interplay between low recombination rates and selection influences neutral ge ...
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