Surprising fitness consequences of GC-biased gene conversion. II. Heterosis.
Heterosis is a widespread phenomenon corresponding to the increase in fitness following crosses between individuals from different populations or lines relative to their parents. Its genetic basis has been a topic of controversy since the early 20th century. The masking of recessive deleterious mutations in hybrids likely explains a substantial part of heterosis. The dynamics and consequences of these mutations have thus been studied in depth. Recently, it was suggested that GC-biased gene conversion (gBGC) might strongly affect the fate of deleterious mutations and may have significant fitness consequences. gBGC is a recombination-associated process mimicking selection in favor of G and C alleles, which can interfere with selection, for instance by increasing the frequency of GC deleterious mutations. I investigated how gBGC could affect the amount and genetic structure of heterosis through an analysis of the interaction between gBGC and selection in subdivided populations. To do so, I analyzed the infinite island model both by numerical computations and by analytical approximations. I showed that gBGC might have little impact on the total amount of heterosis but could greatly affect its genetic basis.
Institut des Sciences de l'Evolution, Université Montpellier II, 34095 Montpellier, France. glemin@univ-montp2.fr
Sylvain
S
Glémin
D001482:Base Composition / Q000235:genetics* / Q000502:physiology*; D005785:Gene Conversion / Q000235:genetics* / Q000502:physiology*; D056426:Genetic Loci / Q000235:genetics; D006801:Humans; D006823:Hybrid Vigor / Q000235:genetics* / Q000502:physiology*; D008957:Models, Genetic; D009154:Mutation; D012641:Selection, Genetic