Of the books I own, Elements of Evolutionary Genetics is one I consult frequently because of its range and comprehensiveness. The authors, Brian Charlesworth and Deborah Charlesworth’s encyclopedic knowledge of the literature. To truly understand the evolutionary process in all its texture and nuance it is important to absorb a fair amount of theory, and Elements of Evolutionary Genetics does do that (though it’s not as abstruse as something like An Introduction to Population Genetics Theory).
When I see a paper by one of the Charlesworths, I try to read it. Not because I have a love of Drosophila or Daphnia, but because to develop strong population-genetics intuitions it always helps to stand on the shoulders of giants. So with that, I pass on this preprint, Mutational load, inbreeding depression and heterosis in subdivided populations:
This paper examines the extent to which empirical estimates of inbreeding depression and inter-population heterosis in subdivided populations, as well as the effects of local population size on mean fitness, can be explained in terms of estimates of mutation rates, and the distribution of selection coefficients against deleterious mutations provided by population genomics data. Using results from population genetics models, numerical predictions of the genetic load, inbreeding depression and heterosis were obtained for a broad range of selection coefficients and mutation rates. The models allowed for the possibility of very high mutation rates per nucleotide site, as is sometimes observed for epiallelic mutations. There was fairly good quantitative agreement between the theoretical predictions and empirical estimates of heterosis and the effects of population size on genetic load, on the assumption that the deleterious mutation rate per individual per generation is approximately one, but there was less good agreement for inbreeding depression. Weak selection, of the order of magnitude suggested by population genomic analyses, is required to explain the observed patterns. Possible caveats concerning the applicability of the models are discussed.