Moritz C, Heideman A, Geffen E, McRae P
Centre for Conservation Biology, University of Queensland, Australia.
Mol Ecol. 1997 Oct;6(10):925-36. doi: 10.1046/j.1365-294x.1997.00268.x.
The Greater Bilby has shown a rapid decline in range during this century and now occupies only a small isolated area in south-western Queensland (QLD) and a larger, but mostly low-density area in the north-western deserts of the Northern Territory (NT) and Western Australia (WA). We have examined variation in the control region of mitochondrial DNA (mtDNA) and at nine microsatellite loci in order to investigate the extent of current and historical subdivision across the species range, and to provide a preliminary assessment of genetic structuring and mating system on a finer scale within the QLD population. Both mtDNA and microsatellite loci had substantial variation within and among populations, with mtDNA divergence being greater between QLD and NT than between NT and WA. The QLD population had two unique and divergent mtDNA lineages, but there was no evidence for strong phylogeographical structure across the range. The available evidence suggests that the bilby should be considered as a single Evolutionarily Significant Unit consisting of multiple Management Units. Augmentation of the remnant QLD population from the NT does not appear necessary at this stage, at least not on genetic grounds. Finer-scale analysis of microsatellite variation for two QLD colonies revealed a deficiency of heterozygotes and significantly greater relatedness within than between colonies. However, structuring was observed only for males; relatedness values for females did not depart from those expected under panmixia. Parentage exclusion analysis for one colony allowed the construction of a partial pedigree which indicated strong polygyny, with one male fathering all but one of the eight offspring assigned. The extent to which fine-scale genetic structuring and differences between sexes is due to sex-biased dispersal vs. effects of mating system remain to be determined.
大兔耳袋狸在本世纪内分布范围迅速缩减，如今仅占据昆士兰州西南部（QLD）的一个小的孤立区域，以及北领地（NT）和西澳大利亚州（WA）西北部沙漠中一个面积较大但大多为低密度的区域。我们检测了线粒体DNA（mtDNA）控制区以及9个微卫星位点的变异情况，以研究该物种分布范围内当前和历史上的分化程度，并对昆士兰州种群内更精细尺度上的遗传结构和交配系统进行初步评估。mtDNA和微卫星位点在种群内部和种群之间都有很大变异，昆士兰州和北领地之间的mtDNA差异大于北领地和西澳大利亚州之间的差异。昆士兰州种群有两个独特且分化的mtDNA谱系，但在整个分布范围内没有证据表明存在强烈的系统地理学结构。现有证据表明，兔耳袋狸应被视为一个由多个管理单元组成的单一进化显著单元。现阶段，从北领地向昆士兰州残余种群进行种群增加似乎没有必要，至少从遗传学角度来看是这样。对昆士兰州两个群落的微卫星变异进行的更精细尺度分析显示，杂合子不足，且群落内部的亲缘关系显著高于群落之间。然而，仅在雄性中观察到了结构；雌性的亲缘关系值并未偏离随机交配预期的值。对一个群落进行的亲权排除分析构建了一个部分谱系，表明存在强烈的一夫多妻制，一只雄性是除一只之外的所有八只后代的父亲。更精细尺度的遗传结构和性别差异在多大程度上是由于性别偏向的扩散与交配系统的影响，仍有待确定。
