Department of Biology, University of Florida, Gainesville, FL 32611-8525, USA.
Am J Primatol. 2013 May;75(5):478-90. doi: 10.1002/ajp.22124. Epub 2013 Jan 10.
Dispersal is a major life history trait of social organisms influencing the behavioral and genetic structure of their groups. Unfortunately, primate dispersal is difficult to quantify, because of the rarity of these events and our inability to ascertain if individuals dispersed or died when they disappear. Socioecological models have been partially developed to understand the ecological causes of different dispersal systems and their social consequences. However, these models have yielded confusing results when applied to folivores. The folivorous red colobus monkey (Procolobus rufomitratus) in Kibale National Park, Uganda is thought to exhibit female-biased dispersal, although both sexes have been observed to disperse and there remains considerable debate over the selective pressures favoring the transfers of males and females and the causes of variation in the proportion of each sex to leave the natal group. We circumvent this problem by using microsatellite DNA data to investigate the prediction that female dispersal will be more frequent in larger groups as compared to smaller ones. The rationale for this prediction is that red colobus exhibit increased within-group competition in bigger groups, which should favor higher female dispersal rates and ultimately lower female relatedness. Genetic data from two unequally sized neighboring groups of red colobus demonstrate increased female relatedness within the smaller group, suggesting females are less likely to disperse when there is less within-group competition. We suggest that the dispersal system is mediated to some degree by scramble competition and group size. Since red colobus group sizes have increased throughout Kibale by over 50% in the last decade, these changes may have major implications for the genetic structure and ultimately the population viability of this endangered primate.
扩散是社会生物的一个主要生活史特征，影响着它们群体的行为和遗传结构。不幸的是，灵长类动物的扩散很难量化，因为这些事件很少发生，而且我们无法确定个体是在消失时扩散还是死亡。社会生态模型已经部分发展起来，以了解不同扩散系统的生态原因及其社会后果。然而，当应用于食叶动物时，这些模型产生了令人困惑的结果。在乌干达的基巴莱国家公园，红疣猴（Procolobus rufomitratus）被认为表现出雌性偏向的扩散，尽管已经观察到雌雄两性都有扩散行为，而且关于支持雄性和雌性转移的选择压力以及导致每只性别的个体离开出生地群体的比例变化的原因仍然存在很大的争议。我们通过使用微卫星 DNA 数据来研究以下预测，即与较小的群体相比，较大的群体中雌性的扩散更为频繁。这一预测的依据是，红疣猴在较大的群体中表现出更高的群体内竞争，这应该有利于更高的雌性扩散率，并最终降低雌性的亲缘关系。来自两个大小不等的红疣猴相邻群体的遗传数据表明，较小群体中的雌性亲缘关系增加，这表明当群体内竞争较少时，雌性不太可能扩散。我们认为，扩散系统在某种程度上受到争夺竞争和群体大小的调节。由于过去十年中，红疣猴的群体大小在基巴莱增加了 50%以上，这些变化可能对这种濒危灵长类动物的遗传结构，最终对其种群活力产生重大影响。
