Fyon Fréderic, Berbel-Filho Waldir M
Department of Biology Royal Holloway University of London Egham UK.
Department of Biology University of Oklahoma Norman Oklahoma USA.
Ecol Evol. 2023 Sep 15;13(9):e10538. doi: 10.1002/ece3.10538. eCollection 2023 Sep.
Hybridization is a natural process whereby two diverging evolutionary lineages reproduce and create offspring of mixed ancestry. Differences in mating systems (e.g., self-fertilization and outcrossing) are expected to affect the direction and extent of hybridization and introgression in hybrid zones. Among other factors, selfers and outcrossers are expected to differ in their mutation loads. This has been studied both theoretically and empirically; however, conflicting predictions have been made on the effects mutation loads of parental species with different mating systems can have on the genomic composition of hybrids. Here, we develop a multi-locus, selective model to study how the different mutation load built up in selfers and outcrossers as a result of selective interference and homozygosity impact the long-term genetic composition of hybrid populations. Notably, our results emphasize that genes from the parental population with lesser mutation load get rapidly overrepresented in hybrid genomes, regardless of the hybrids own mating system. When recombination tends to be more important than mutation, outcrossers' genomes tend to be of higher quality and prevail. When recombination rates are low, however, selfers' genomes may reach higher quality than outcrossers' genomes and prevail in the hybrids. Taken together, these results provide concrete insights into one of the multiple factors influencing hybrid genome ancestry and introgression patterns in hybrid zones containing species with different mating systems.
杂交是一个自然过程，通过这个过程，两个分化的进化谱系进行繁殖并产生具有混合血统的后代。交配系统的差异（例如自花受精和异花受精）预计会影响杂交区域中杂交和基因渗入的方向与程度。在其他因素中，自花授粉植物和异花授粉植物的突变负荷预计会有所不同。这一点已经在理论和实证方面都得到了研究；然而，对于具有不同交配系统的亲本物种的突变负荷对杂种基因组组成的影响，却得出了相互矛盾的预测结果。在这里，我们构建了一个多位点选择模型，以研究由于选择干扰和纯合性，自花授粉植物和异花授粉植物中积累的不同突变负荷如何影响杂交种群的长期遗传组成。值得注意的是，我们的结果强调，来自突变负荷较小的亲本种群的基因在杂交基因组中会迅速过度占比，而不论杂种自身的交配系统如何。当重组比突变更重要时，异花授粉植物的基因组往往质量更高并占主导地位。然而，当重组率较低时，自花授粉植物的基因组可能会比异花授粉植物的基因组质量更高，并在杂种中占主导地位。综上所述，这些结果为影响包含不同交配系统物种的杂交区域中杂交基因组祖先和基因渗入模式的多种因素之一提供了具体见解。
