Weadick Cameron J, Sommer Ralf J
Am Nat. 2016 Apr;187(4):517-31. doi: 10.1086/685283. Epub 2016 Feb 18.
Interactions between the sexes influence evolution at many scales, but not all animal species conform to the familiar male-female (dioecious) mating system; such taxa are powerful tools for studying the evolutionary importance of sexual selection and conflict on all manner of life-history traits, including longevity. We tested for an effect of mating system on adult life span in Pristionchus nematodes, where self-fertile hermaphrodites have replaced females multiple times independently throughout the genus (androdioecy). By measuring adult life span for 11 species (6 dioecious, 5 androdioecious), we found that life span is considerably shorter in hermaphrodites relative to closely related females. This effect is not a cost of reproduction; brood size did not reliably trade off with life span in self-fertilizing hermaphrodites or in mated females. Furthermore, we found that sexual dimorphism in life span varied among dioecious species, with females generally outliving males. Finally, we documented intraspecific variation for life span and cuticular disease (blistering) prevalence in Pristionchus pacificus, a model system for evolutionary-developmental biology. This work demonstrates that mating system transitions and life span evolution are linked in Pristionchus nematodes and provides a foundation for future comparative and mechanistic studies of aging in this genus.
两性之间的相互作用在多个尺度上影响着进化，但并非所有动物物种都符合常见的雌雄异体（两性异体）交配系统；这类分类群是研究性选择和冲突对包括寿命在内的各种生活史特征的进化重要性的有力工具。我们测试了交配系统对Pristionchus线虫成虫寿命的影响，在该线虫中，能自我受精的雌雄同体在整个属中多次独立取代了雌性（雄雌同体）。通过测量11个物种（6个两性异体、5个雄雌同体）的成虫寿命，我们发现雌雄同体的寿命相对于其亲缘关系较近的雌性要短得多。这种影响并非繁殖的代价；在自我受精的雌雄同体或已交配的雌性中，产卵量与寿命之间并没有可靠的权衡关系。此外，我们发现两性异体物种之间寿命的两性差异各不相同，雌性通常比雄性寿命长。最后，我们记录了太平洋Pristionchus线虫（一种进化发育生物学的模式系统）在寿命和表皮疾病（起泡）患病率方面的种内变异。这项工作表明，交配系统转变与Pristionchus线虫的寿命进化有关，并为该属未来衰老的比较研究和机制研究奠定了基础。
