Chenoweth Stephen F, Hughes Jane M
Molecular Ecology Laboratory, Faculty of Environmental Sciences, Griffith University, Nathan, Queensland, Australia 4111.
Mol Ecol. 2003 Sep;12(9):2387-97. doi: 10.1046/j.1365-294x.2003.01921.x.
We assayed mtDNA haplotype [300 base pairs (bp) control region] geography and genealogy in the Indo-Pacific tasselfish, Polynemus sheridani from its contiguous estuarine distribution across northern Australia (n = 169). Eight estuaries were sampled from three oceanographic regions (Timor Sea, Gulf of Carpentaria and the Coral Sea) to assess the impact of Pleistocene sea level changes on the historical connectivity among P. sheridani populations. Specifically, we investigated the genetic consequences of disruption to Indian-Pacific Ocean connectivity brought about by the closure of the Torres Strait. Overall there was significant population subdivision among estuaries (FST = 0.161, PhiST = 0.187). Despite a linear distribution, P. sheridani did not show isolation by distance over the entire sampled range because of genetic similarity of estuaries greater than 3000 km apart. However, significant isolation by distance was detected between estuaries separated by less than 3000 km of coastline. Unlike many genetic studies of Indo-Pacific marine species, there was no evidence for an historical division between eastern and western populations. Instead, phylogeographical patterns were dominated by a starlike intraspecific phylogeny coupled with evidence for population expansion in both the Gulf of Carpentaria and the Coral Sea but not the Timor Sea. This was interpreted as evidence for recent west to east recolonization across of northern Australia following the last postglacial marine advance. We argue that although sufficient time has elapsed postcolonization for populations to approach gene flow-drift equilibrium over smaller spatial scales (< 3000 km), the signal of historical colonization persists to obscure the expected equilibrium pattern of isolation by distance over large spatial scales (> 3000 km).
我们对印度-太平洋地区的流苏鱼（Polynemus sheridani）的线粒体DNA单倍型（300个碱基对的控制区）地理分布和谱系进行了分析，该流苏鱼分布于澳大利亚北部相邻的河口区域（n = 169）。从三个海洋学区域（帝汶海、卡奔塔利亚湾和珊瑚海）的八个河口采集样本，以评估更新世海平面变化对P. sheridani种群间历史连通性的影响。具体而言，我们研究了托雷斯海峡关闭导致的印度洋-太平洋连通性中断的遗传后果。总体而言，各河口之间存在显著的种群细分（FST = 0.161，PhiST = 0.187）。尽管P. sheridani呈线性分布，但在整个采样范围内并未表现出距离隔离，这是因为相距超过3000公里的河口之间存在遗传相似性。然而，在海岸线距离小于3000公里的河口之间检测到了显著的距离隔离。与许多对印度-太平洋海洋物种的遗传研究不同，没有证据表明东部和西部种群之间存在历史分化。相反，系统发育地理模式以星状种内系统发育为主，同时有证据表明卡奔塔利亚湾和珊瑚海的种群发生了扩张，而帝汶海没有。这被解释为末次冰期后海洋推进后，近期从西向东重新殖民澳大利亚北部的证据。我们认为，尽管殖民后已经有足够的时间让种群在较小空间尺度（< 3000公里）上接近基因流-漂变平衡，但历史殖民的信号仍然存在，掩盖了在大空间尺度（> 3000公里）上预期的距离隔离平衡模式。
