Washburn Brooke A, Cashner Mollie F, Blanton Rebecca E
Department of Biology Center of Excellence for Field Biology Austin Peay State University Clarksville TN USA.
Present address: Department of Biological Sciences University of Denver Denver CO USA.
Ecol Evol. 2020 Feb 6;10(4):2253-2268. doi: 10.1002/ece3.6064. eCollection 2020 Feb.
Genetic connectivity is expected to be lower in species with limited dispersal ability and a high degree of habitat specialization (intrinsic factors). Also, gene flow is predicted to be limited by habitat conditions such as physical barriers and geographic distance (extrinsic factors). We investigated the effects of distance, intervening pools, and rapids on gene flow in a species, the Tuxedo Darter (), a habitat specialist that is presumed to be dispersal-limited. We predicted that the interplay between these intrinsic and extrinsic factors would limit dispersal and lead to genetic structure even at the small spatial scale of the species range (a 38.6 km river reach). The simple linear distribution of allowed for an ideal test of how these factors acted on gene flow and allowed us to test expectations (e.g., isolation-by-distance) of linearly distributed species. Using 20 microsatellites from 163 individuals collected from 18 habitat patches, we observed low levels of genetic structure that were related to geographic distance and rapids, though these factors were not barriers to gene flow. Pools separating habitat patches did not contribute to any observed genetic structure. Overall, maintains gene flow across its range and is comprised of a single population. Due to the linear distribution of the species, a stepping-stone model of dispersal best explains the maintenance of gene flow across its small range. In general, our observation of higher-than-expected connectivity likely stems from an adaptation to disperse due to temporally unstable and patchy habitat.
对于扩散能力有限且栖息地专业化程度高的物种（内在因素），预计其基因连通性较低。此外，基因流预计会受到诸如物理屏障和地理距离等栖息地条件的限制（外在因素）。我们研究了距离、中间的水塘和急流对一种名为燕尾镖鲈（Tuxedo Darter）的物种基因流的影响，该物种是一种栖息地 specialists，被认为扩散能力有限。我们预测，这些内在和外在因素之间的相互作用会限制扩散，甚至在该物种分布范围的小空间尺度（一条38.6公里长的河段）上导致遗传结构的形成。其简单的线性分布为测试这些因素如何作用于基因流提供了理想条件，并使我们能够检验线性分布物种的预期（例如距离隔离）。利用从18个栖息地斑块收集的163个个体的20个微卫星，我们观察到与地理距离和急流相关的低水平遗传结构，尽管这些因素并非基因流的障碍。分隔栖息地斑块的水塘对观察到的任何遗传结构都没有贡献。总体而言，燕尾镖鲈在其分布范围内维持着基因流，并且由单一群体组成。由于该物种的线性分布，逐步跳跃的扩散模型最能解释其在小范围内基因流的维持。一般来说，我们观察到的高于预期的连通性可能源于对由于时间上不稳定且斑块状的栖息地而进行扩散的适应。
