Data from: Repeated land mass reformation limits diversification in the widespread littoral zone mosquito Anopheles sundaicus sensu lato in the Indo-Oriental Region

Southeast Asia harbours abundant biodiversity, hypothesized to have been generated by Pliocene and Pleistocene climatic and environmental change. Vicariance between the island of Borneo, the remaining Indonesian archipelago and mainland Southeast Asia caused by elevated sea levels during interglacial periods has been proposed to lead to diversification in the littoral zone mosquito Anopheles (Cellia) sundaicus (Rodenwaldt) sensu lato. To test this biogeographical hypothesis, we inferred the population history and assessed gene flow of A. sundaicus s.l. sampled from 18 populations across its pan-Asian species range, using sequences from mitochondrial cytochrome c oxidase subunit 1 (CO1), the internal transcribed spacer 2 (ITS2) and the mannose phosphate isomerase (Mpi) gene. A hypothesis of ecological speciation for A. sundaicus involving divergent adaptation to brackish and freshwater larval habitats was also previously proposed, based on a deficiency of heterozygotes for Mpi allozyme alleles in sympatry. This hypothesis was not supported by Mpi sequence data, which exhibited no fixed differences between brackish and freshwater larval habitats. Mpi and CO1 supported the presence of up to eight genetically distinct population groupings. Counter to the hypothesis of three allopatric species, divergence was often no greater between Borneo, Sumatra/Java and the Southeast Asian mainland than it was between genetic groupings within these landmasses. An isolation-with-migration (IM) model indicates recurrent gene flow between the current major landmasses. Such gene flow would have been possible during glacial periods when the current landmasses merged, presenting opportunities for dispersal along expanding and contracting coastlines. Consequently, Pleistocene climatic variation has proved a homogenizing, rather than diversifying, force for A. sundaicus diversity.

东南亚拥有极为丰富的生物多样性，该多样性被推测为上新世（Pliocene）与更新世（Pleistocene）时期的气候及环境变迁所塑造。此前有研究提出，间冰期海平面上升导致婆罗洲（Borneo）、其余印度尼西亚群岛与东南亚大陆之间产生地理分隔（vicariance），这一事件可能推动了潮间带（littoral zone）蚊虫广义苏拉威西按蚊（Anopheles (Cellia) sundaicus (Rodenwaldt) sensu lato）的物种分化。为验证这一生物地理学假说，本研究采集了该物种在泛亚洲分布范围内的18个种群样本，基于线粒体细胞色素c氧化酶亚基1（CO1）、内部转录间隔区2（ITS2）以及磷酸甘露糖异构酶（Mpi）基因的序列数据，推断其种群历史并评估基因流动情况。此前还有研究基于同域分布（sympatry）种群中Mpi同工酶（allozyme）等位基因杂合子缺失的现象，提出了苏拉威西按蚊的生态物种形成假说：该物种会对咸水与淡水幼虫生境产生趋异适应，但Mpi序列数据并不支持该假说——咸水与淡水幼虫生境的种群间未出现固定遗传差异。Mpi与CO1基因数据显示，该物种可被划分为最多8个遗传分化显著的种群集群。与“该类群包含3个异域分布（allopatric）物种”的假说相悖，婆罗洲、苏门答腊/爪哇与东南亚大陆之间的遗传分化程度，往往并不高于这些陆块内部不同种群集群之间的分化水平。隔离与迁移（isolation-with-migration, IM）模型显示，当前各大陆块之间存在持续的基因交流，在冰期阶段，当前各陆块会彼此相连，此时蚊虫可沿海岸线的扩张与收缩进行扩散，因此这种基因交流是可行的。综上，更新世的气候波动对苏拉威西按蚊的多样性而言，起到的是同质化作用而非驱动分化的作用。