Laboratorio de Ecofisiología, Departamento de Biología, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Casilla de Correo 1245, Mar del Plata, Argentina.
BMC Genet. 2010 Jan 28;11:9. doi: 10.1186/1471-2156-11-9.
The population genetic structure of subterranean rodent species is strongly affected by demographic (e.g. rates of dispersal and social structure) and stochastic factors (e.g. random genetic drift among subpopulations and habitat fragmentation). In particular, gene flow estimates at different spatial scales are essential to understand genetic differentiation among populations of a species living in a highly fragmented landscape. Ctenomys australis (the sand dune tuco-tuco) is a territorial subterranean rodent that inhabits a relatively secure, permanently sealed burrow system, occurring in sand dune habitats on the coastal landscape in the south-east of Buenos Aires province, Argentina. Currently, this habitat is threatened by urban development and forestry and, therefore, the survival of this endemic species is at risk. Here, we assess population genetic structure and patterns of dispersal among individuals of this species at different spatial scales using 8 polymorphic microsatellite loci. Furthermore, we evaluate the relative importance of sex and habitat configuration in modulating the dispersal patterns at these geographical scales.
Our results show that dispersal in C. australis is not restricted at regional spatial scales (approximately 4 km). Assignment tests revealed significant population substructure within the study area, providing support for the presence of two subpopulations from three original sampling sites. Finally, male-biased dispersal was found in the Western side of our study area, but in the Eastern side no apparent philopatric pattern was found, suggesting that in a more continuous habitat males might move longer distances than females.
Overall, the assignment-based approaches were able to detect population substructure at fine geographical scales. Additionally, the maintenance of a significant genetic structure at regional (approximately 4 km) and small (less than 1 km) spatial scales despite apparently moderate to high levels of gene flow between local sampling sites could not be explained simply by the linear distance among them. On the whole, our results support the hypothesis that males disperse more frequently than females; however they do not provide support for strict philopatry within females.
穴居啮齿动物的种群遗传结构受到人口统计学因素（例如扩散率和社会结构）和随机因素（例如亚种群间的随机遗传漂变和栖息地破碎化）的强烈影响。特别是，在不同的空间尺度上估计基因流动对于理解生活在高度破碎景观中的物种的种群遗传分化至关重要。Ctenomys australis（沙丘 tuco-tuco）是一种具有领地性的穴居啮齿动物，栖息在阿根廷布宜诺斯艾利斯省东南部沿海沙丘栖息地相对安全且永久封闭的洞穴系统中。目前，这种栖息地受到城市发展和林业的威胁，因此，这种特有物种的生存面临风险。在这里，我们使用 8 个多态微卫星基因座评估了该物种在不同空间尺度上的个体遗传结构和扩散模式。此外，我们评估了性别和栖息地配置在调节这些地理尺度上的扩散模式中的相对重要性。
我们的结果表明，C. australis 的扩散不受区域空间尺度（约 4 公里）的限制。分配测试显示，在研究区域内存在显著的种群亚结构，为三个原始采样点存在两个亚种群提供了支持。最后，在我们研究区域的西侧发现了雄性偏向的扩散，但在东侧没有发现明显的恋地性模式，这表明在更连续的栖息地中，雄性可能比雌性移动更远的距离。
总体而言，基于分配的方法能够在精细的地理尺度上检测到种群亚结构。此外，尽管局部采样点之间存在中等至高的基因流，但在区域（约 4 公里）和小（小于 1 公里）空间尺度上仍保持显著的遗传结构，这不能仅仅用它们之间的直线距离来解释。总的来说，我们的结果支持雄性比雌性更频繁扩散的假设；然而，它们并没有为雌性严格的恋地性提供支持。
