Data from: Hybrid crosses and the genetic basis of interspecific divergence in lifespan in Pristionchus nematodes

Characterizing the genetic basis of among-species variation in lifespan is a major goal of evolutionary gerontology research, but the very feature that defines separate species—the inability to interbreed—makes achieving this goal impractical, if not impossible, for most taxa. Pristionchus nematodes provide an intriguing system for tackling this problem, as female lifespan varies among species that can be crossed to form viable (though infertile) hybrids. By conducting reciprocal crosses among three species—two dioecious (long-lived P. exspectatus and short-lived P. arcanus) and one androdioecious (short-lived P. pacificus)—we found that female lifespan was long for all hybrids, consistent with the hypothesis that the relatively short lifespans seen for P. pacificus hermaphrodites and P. arcanus females are caused by independent, recessive alleles that are masked in hybrid genomes. Cross direction had a small effect on survivorship for crosses involving P. exspectatus, indicating that nuclear-mitochondrial interactions may also influence Pristionchus longevity. Our findings suggest that long lifespan in P. exspectatus reflects the realization of an ancestral potential for extended longevity in the P. pacificus species complex. This work demonstrates the utility of interspecific hybrids for ageing research and provides a foundation for future work on the genetic architecture of interspecific lifespan variation.

解析物种间寿命差异的遗传基础，是进化老年学（evolutionary gerontology）研究的核心目标之一；然而，界定不同物种的关键特征——生殖隔离（即跨物种无法交配）——使得绝大多数类群难以达成这一目标，即便并非完全不可能。薄咽线虫属（Pristionchus）线虫为解决这一难题提供了极具研究价值的实验体系：该属内多个物种可杂交产生可存活（但不育）的杂交后代，但其雌性寿命却存在显著差异。我们针对三个物种开展正反交实验：其中两个为雌雄异体（dioecious）物种——长寿命的P. exspectatus与短寿命的P. arcanus，另一个为雄雌同体（androdioecious）物种——短寿命的P. pacificus。实验结果显示，所有杂交后代的雌性寿命均较长，这与下述假说一致：P. pacificus雌雄同体个体与P. arcanus雌性个体的相对短寿表型，由独立的隐性等位基因所致，而这类等位基因在杂交基因组中会被掩盖。在涉及P. exspectatus的杂交组合中，交配方向对存活率仅存在微弱影响，这表明核-线粒体互作同样可能影响薄咽线虫属线虫的寿命。本研究结果表明，P. exspectatus的长寿命特性，实则体现了太平洋薄咽线虫（P. pacificus）物种复合体祖先所具备的长寿潜能。此项研究证实了跨物种杂交后代在衰老研究中的应用价值，同时为后续解析物种间寿命差异的遗传结构奠定了坚实基础。