Mating system transitions drive life span evolution in Pristionchus nematodes

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 ...两性间的相互作用会在多个尺度上影响演化进程，但并非所有动物物种都遵循常见的雌雄异体（dioecious）交配系统；这类类群是研究性选择与性冲突对包括寿命在内的各类生活史特征演化重要性的有力工具。我们针对Pristionchus属线虫（Pristionchus nematodes）的交配系统对成虫寿命的影响开展了测试——该属内多次独立演化出可自我繁殖的雌雄同体（hermaphrodite）以替代雌性个体，即雄雌同体（androdioecy）生殖系统。通过对11个物种（6个雌雄异体类群、5个雄雌同体类群）的成虫寿命进行测量，我们发现相较于近缘物种的雌性个体，雌雄同体的寿命显著更短。该效应并非繁殖成本所致；在自我繁殖的雌雄同体或已交配的雌性个体中，窝卵数并未与寿命呈现可靠的权衡关系。此外，我们还发现雌雄异体物种间的寿命两性异形存在差异，雌性个体通常比雄性更长寿。最后，我们……