Department of General Zoology, Institute of Biology, University of Duisburg-Essen, Essen, Germany.
PLoS One. 2011 Apr 13;6(4):e18757. doi: 10.1371/journal.pone.0018757.
African mole-rats (Bathyergidae, Rodentia) contain several social, cooperatively breeding species with low extrinsic mortality and unusually high longevity. All social bathyergids live in multigenerational families where reproduction is skewed towards a few breeding individuals. Most of their offspring remain as reproductively inactive "helpers" in their natal families, often for several years. This "reproductive subdivision" of mole-rat societies might be of interest for ageing research, as in at least one social bathyergid (Ansell's mole-rats Fukomys anselli), breeders have been shown to age significantly slower than non-breeders. These animals thus provide excellent conditions for studying the epigenetics of senescence by comparing divergent longevities within the same genotypes without the inescapable short-comings of inter-species comparisons. It has been claimed that many if not all social mole-rat species may have evolved similar ageing patterns, too. However, this remains unclear on account of the scarcity of reliable datasets on the subject. We therefore analyzed a 20-year breeding record of Giant mole-rats Fukomys mechowii, another social bathyergid species. We found that breeders indeed lived significantly longer than helpers (ca. 1.5-2.2fold depending on the sex), irrespective of social rank or other potentially confounding factors. Considering the phylogenetic positions of F. mechowii and F. anselli and unpublished data on a third Fukomys-species (F. damarensis) showing essentially the same pattern, it seems probable that the reversal of the classic trade-off between somatic maintenance and sexual reproduction is characteristic of the whole genus and hence of the vast majority of social mole-rats.
非洲蹄兔（非洲蹄兔科，啮齿目）包含几种具有低外部死亡率和异常高寿命的社会性、合作繁殖物种。所有社会性蹄兔都生活在多代同堂的家庭中，繁殖偏向少数繁殖个体。它们的大多数后代仍然是在其出生地家庭中没有生殖能力的“帮手”，通常会持续几年。这种蹄兔社会的“生殖分工”可能对衰老研究感兴趣，因为至少有一种社会性蹄兔（安塞尔氏蹄兔 Fukomys anselli）中，繁殖者的衰老速度明显比非繁殖者慢。因此，这些动物为通过比较同一基因型内不同的长寿来研究衰老的表观遗传学提供了极好的条件，而不必考虑物种间比较不可避免的缺点。有人声称，许多（如果不是全部的话）社会性蹄兔物种可能也进化出了类似的衰老模式。然而，由于缺乏关于这个主题的可靠数据集，这一点仍然不清楚。因此，我们分析了另一种社会性蹄兔物种巨蹄兔 Fukomys mechowii 的 20 年繁殖记录。我们发现，繁殖者的寿命确实明显长于帮手（取决于性别，约为 1.5-2.2 倍），而与社会等级或其他潜在的混杂因素无关。考虑到 F. mechowii 和 F. anselli 的系统发育位置以及未发表的关于第三个蹄兔物种（F. damarensis）的数据显示出基本相同的模式，很可能经典的体维持和有性繁殖之间的权衡被逆转是整个属的特征，因此也是绝大多数社会性蹄兔的特征。
