The genetic basis and experimental evolution of inbreeding depression in Caenorhabditis elegans

Determining the genetic basis of inbreeding depression is important for understanding the role of selection in the evolution of mixed breeding systems. Here, we investigate how androdioecy (a breeding system characterized by partial selfing and outcrossing) and dioecy (characterized by obligatory outcrossing) influence the experimental evolution of inbreeding depression in Caenorhabditis elegans. We derived inbred lines from ancestral and evolved populations and found that the dioecious lineages underwent more extinction than androdioecious lineages. For both breeding systems, however, there was selection during inbreeding because the diversity patterns of 337 single-nucleotide polymorphisms (SNPs) among surviving inbred lines deviated from neutral expectations. In parallel, we also followed the evolution of embryo to adult viability, which revealed similar starting levels of inbreeding depression in both breeding systems, but also outbreeding depression. Under androdioecy, diversity at...解析近交衰退（inbreeding depression）的遗传基础，对于理解选择在混合繁殖系统演化中的作用具有重要意义。本研究以秀丽隐杆线虫（Caenorhabditis elegans）为对象，探究雄全同株（androdioecy，一种以部分自交与异交为特征的繁殖系统）与雌雄异株（dioecy，一种以专性异交为特征的繁殖系统）如何影响其近交衰退的实验演化进程。我们从祖先种群与演化种群中构建近交系，发现雌雄异株谱系的灭绝比例高于雄全同株谱系。不过，在两种繁殖系统下，近交过程中均存在选择作用：存活近交系的337个单核苷酸多态性（single-nucleotide polymorphisms, SNPs）的多样性模式偏离了中性预期。与此同时，我们还追踪了胚胎至成虫的存活力演化，结果显示两种繁殖系统的近交衰退初始水平相近，但同时也存在远交衰退（outbreeding depression）。在雄全同株系统下，……