Anthropological Institute & Museum, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland.
Mol Ecol. 2012 Jul;21(13):3352-62. doi: 10.1111/j.1365-294X.2012.05608.x. Epub 2012 May 31.
Philopatry and sex-biased dispersal have a strong influence on population genetic structure, so the study of species dispersal patterns and evolutionary mechanisms shaping them are of great interest. Particularly nongregarious mammalian species present an underexplored field of study: despite their lower levels of sociality compared to group-living species, interactions among individuals do occur, providing opportunities for cryptic kin selection. Among the least gregarious primates are orang-utans (genus: Pongo), in which preferential associations among females have nevertheless been observed, but for which the presence of kin structures was so far unresolved because of the equivocal results of previous genetic studies. To clarify relatedness and dispersal patterns in orang-utans, we examined the largest longitudinal set of individuals with combined genetic, spatial and behavioural data. We found that males had significantly higher mitochondrial DNA (mtDNA) variation and more unique haplotypes, thus underscoring their different maternal ancestries compared to females. Moreover, pedigree reconstruction based on 24 highly polymorphic microsatellite markers and mtDNA haplotypes demonstrated the presence of three matrilineal clusters of generally highly related females with substantially overlapping ranges. In orang-utans and possibly other nongregarious species, comparing average biparental relatedness (r) of males and females to infer sex-biased dispersal is extremely problematic. This is because the opportunistic sampling regime frequently employed in nongregarious species, combined with overlapping space use of distinct matrilineal clusters, leads to a strong downward bias when mtDNA lineage membership is ignored. Thus, in nongregarious species, correct inferences of dispersal can only be achieved by combining several genetic approaches with detailed spatial information.
亲代亲缘选择和性别偏向的扩散对种群遗传结构有很强的影响，因此，研究物种的扩散模式和塑造它们的进化机制是非常有意义的。特别地，非群居的哺乳动物物种是一个研究不足的领域：尽管它们的社交性比群居物种低，但个体之间确实会发生相互作用，为隐蔽的亲缘选择提供了机会。在最不群居的灵长类动物中，猩猩（属：Pongo）就是一个例子，尽管已经观察到雌性之间存在优先关联，但由于之前的遗传研究结果模棱两可，亲缘结构的存在至今仍未得到解决。为了澄清猩猩的亲缘关系和扩散模式，我们检查了结合遗传、空间和行为数据的最大纵向个体数据集。我们发现，雄性的线粒体 DNA（mtDNA）变异和独特的单倍型明显更高，这突显出它们与雌性的母系祖先不同。此外，基于 24 个高度多态性微卫星标记和 mtDNA 单倍型的系谱重建表明，存在三个母系亲缘关系通常高度相关的集群，且它们的范围有很大的重叠。在猩猩和可能其他非群居物种中，比较雄性和雌性的平均双亲亲缘关系（r）来推断性别偏向的扩散是非常成问题的。这是因为非群居物种中经常采用的机会主义采样方案，加上不同母系亲缘关系集群的空间使用重叠，导致当忽略 mtDNA 谱系成员身份时，会产生强烈的向下偏差。因此，在非群居物种中，只有通过将几种遗传方法与详细的空间信息相结合，才能正确推断扩散。
