About this Research Topic
An important aim in conservation genetics is preserving species by using neutral genetic diversity of populations as an indicator of population viability and extinction risk, under the assumption that high genetic diversity results in high adaptive potential and low genetic load (decrease of the fitness of the average genotype relative to the fittest genotype), and thereby in increased individual fitness and long-term population survival. This assumption is highly debated. Further, even when the genetic load is high effects on population viability may be limited or even non-existent. Although a high genetic load can strongly increase local extinction risk, mostly via inbreeding (inbreeding depression), it does not necessarily result in a reduced population growth rate.
It has been argued that in many cases deleterious alleles responsible for the genetic load have a limited impact because of density-dependent processes. Consequently, population size and persistence often do not seem to be affected by the presence of deleterious alleles, even when they are clearly expressed, as shown by e.g. low survival, low reproductive rate, and increased susceptibility to pathogens. Alternatively, deleterious alleles may be epigenetically suppressed. Epigenetic regulation may limit the impact of low genetic diversity on population viability by increasing phenotypic variation. However, the absence of a clear impact of genetic load and inbreeding on population viability may also be (partly) a consequence of underreporting. To date, there are still only a few case studies assessing the magnitude of genetic load and inbreeding depression in the wild, let alone linking this to population viability.
In this Research Topic, we welcome studies on the relationship between neutral diversity, functional diversity, and deleterious alleles on the one hand and inbreeding depression, individual fitness, epigenetic regulation, and population viability on the other. In particular, we would like to address the following three questions:
1) Under what circumstances do low genetic diversity and high genetic load, via inbreeding, result in decreased population viability?
2) Why are some populations stable, or even thriving, despite high inbreeding?
3) What is the role of epigenetic regulation in (suppressing) inbreeding depression and population viability?
Keywords: Inbreeding Depression, Genetic Load, Deleterious Alleles, Population Viability
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