人类社会的家庭结构和居住形式多种多样。在大多数社会的婚姻中，女性通常离开自己父母的家庭与配偶居住在一起，即所谓的女性扩散模式。在少数的母系社会中则是丈夫到妻子家与其亲属一起居住，也称男性扩散。在极少数社会中，无论男女都不扩散，他们一生居住在自己出生的家庭中。例如生活在我国西南部的少数民族-摩梭人，他们终生居住在母系大家庭中，与兄弟姐妹共同生活，其婚姻形式为“走婚”婚姻。
中科院动物研究所陶毅研究组研究了在这种较为罕见的家庭结构和居住形式中家庭成员的生育（繁殖）冲突，分析了影响摩梭男性和女性繁殖成功的主要因素。其主要研究结果表明：（1）共同居住的女性亲属之间（姐妹间或表姐妹间）存在生育（繁殖）竞争，并且共同居住的女性亲属数量越多，平均每一女性个体的繁殖成功率越低；（2）男性的繁殖成功则与家庭内的亲属数量无关，共同居住的男性与他们的兄弟之间不存在繁殖竞争；（3）女性表亲之间的繁殖竞争比同母姐妹之间的竞争更为激烈。研究人员还使用“tug-of-war”模型研究了姐妹间及表姐妹间的竞争模式及可能导致的繁殖后果。该模型假设将资源用于竞争可以被看作是一种“自私”的行为。结果表明，当两个女性亲属竞争繁殖资源时，占优势的姐姐（或年长的个体）比占劣势的妹妹（或年幼的个体）用于竞争的资源投入较少（更为合作），且会获得较多的繁殖成功；而在竞争中利用资源的能力较弱的妹妹则须为竞争中投入更多的资源（更少合作），但仍获得较低的繁殖成功。实际的观测数据支持了理论模型的预测。在需要母系大家庭的所有成员合作劳动的农忙季节中，研究人员发现，在平均意义上，妹妹比姐姐更少在土地中劳动。这应当是妹妹竞争行为的一种体现，也可能是由于与姐姐相比她与整个家庭的平均亲缘关系较低。
此项研究结果已在线发表在英国皇家学会刊物Philosophical Transactions of the Royal Society B。第一作者为季婷；通信作者为陶毅，Ruth Mace。（生物谷Bioon.com）
生物谷推荐的英文摘要
Philosophical Transactions of the Royal Society B doi: 10.1098/rstb.2013.0081
Reproductive competition between females in the matrilineal Mosuo of southwestern China
Ting Ji1， Jia-Jia Wu2， Qiao-Qiao He1， Jing-Jing Xu3， Ruth Mace2 and Yi Tao1
The matrilineal Mosuo of southwestern China live in communal households where brothers and sisters of three generations live together (duolocal residence)， and men visit their wives， who reside elsewhere， only at night in ‘visiting’ marriages. Here we show that these communally breeding sisters are in reproductive conflict， in the sense that they share the resources needed to reproduce. We analyse determinants of reproductive success in females and males， and show that co-resident female kin are in competition； the more female kin reside in the household， the more reproductive success is reduced. Male reproductive success， however， is not determined by the kin in his natal household； duolocal males are not in reproductive conflict with their siblings. Competition with female cousins can be worse than that between sisters. We also find that female work on the farm (which is the main communal resource) is not equal. We use a ‘tug-of-war’ model of reproductive skew generated by incomplete control， to model the patterns of effort put into competition between sisters and cousins. The model predicts that more dominant (older) sisters will put less effort into reproductive conflict than will less dominant (younger) sisters； but younger sisters will also have lower reproductive success because they are less efficient at gaining access to the shared resource. Both predictions are consistent with our data. Younger sisters work less in the fields than do older sisters， which may represent a form of conflict or may be because their average relatedness to the household is lower than that of their more fertile older sisters.
