Social organisation and genetic structure: insights from co-distributed bat populations

The impact of ecology and social organisation on genetic structure at landscape spatial scales, where gene dynamics shape evolution as well as determine susceptibility to habitat fragmentation, is poorly understood. Attempts to assess these effects must take into account the potentially confounding effects of history. We used microsatellites to compare genetic structure in seven bat species with contrasting patterns of roosting ecology and social organisation, all of which are co-distributed in an ancient forest habitat that has been exceptionally buffered from radical habitat shifts. Over one thousand individuals were captured at foraging sites and genotyped at polymorphic microsatellite loci. Analyses of spatially explicit genotype data revealed inter-species differences in the extent of movement and gene flow and genetic structure across continuous intact forest. Highest positive genetic structure was observed in tree-roosting taxa that roost either alone or in small groups. By comparison, a complete absence of genetic autocorrelation was noted in the cave-roosting colonial species across the study area. Our results thus reveal measurable inter-species differences in the natural limits of gene flow in an unmodified habitat, which we attribute to contrasting roosting ecology and social organisation. The consequences of ecology and behaviour for gene flow have important implications for conservation. In particular, tree-roosting species characterised by lower vagility and thus gene flow will be disproportionally impacted by landscape-scale forest clearance and habitat fragmentation, which are prevalent in the study region. Our method also highlights the usefulness of rapid sampling of foraging bats for assaying genetic structure, particularly where roosting sites are not always known.

在景观空间尺度下，生态与社会组织如何影响遗传结构——其中基因动态既塑造演化进程，又决定物种对生境破碎化的易感性——这一问题迄今仍未得到充分阐释。若要评估上述影响，必须将历史因素可能带来的混淆效应纳入考量。本研究采用微卫星（microsatellites）标记，对7种栖息生态与社会组织模式存在显著差异的蝙蝠物种的遗传结构进行比较分析；所有研究物种均同域分布于一处得以最大限度规避剧烈生境变化的古老森林生境中。研究人员在觅食位点共捕获逾千只蝙蝠个体，并对其多态性微卫星位点进行基因分型。通过对空间显性基因型数据的分析，研究人员发现，在连续完整的森林生境中，不同蝙蝠物种的活动范围、基因流水平与遗传结构均存在显著种间差异。单独或小集群栖息的树栖类群呈现出最高程度的正向遗传结构。相较之下，整个研究区域内的洞栖集群物种则完全未表现出遗传自相关现象。因此，本研究结果揭示了未受干扰生境中基因流自然上限的显著种间差异，我们将其归因于不同类群间栖息生态与社会组织模式的差异。生态与行为特征对基因流的影响，对物种保护工作具有重要启示意义。具体而言，研究区域内普遍存在景观尺度的森林砍伐与生境破碎化现象，而扩散能力较弱、进而基因流水平较低的树栖物种，将受到不成比例的严重影响。本研究方法同时表明，通过对觅食蝙蝠的快速采样来测定遗传结构具有较高实用性，尤其是在栖息位点难以确定的情况下。