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，学界推测其形成源于上新世与更新世时期的气候与环境变化。间冰期海平面上升导致婆罗洲岛、其余印尼群岛与东南亚大陆之间产生地理隔离，这一事件被认为推动了潮间带按蚊属塞蚊亚属（Cellia）孙达库按蚊（Anopheles (Cellia) sundaicus (Rodenwaldt) sensu lato）的物种分化。为验证这一生物地理学假说，我们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，对该泛亚洲分布物种的18个采样种群开展种群历史推断与基因流评估。此前有研究基于同域分布种群中Mpi同工酶等位基因杂合子缺失的现象，提出了孙达库按蚊广义种的生态物种形成假说：该物种因对咸水与淡水幼虫生境产生趋异适应而形成新物种。但本研究的Mpi序列数据并不支持这一假说——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基因数据支持存在至多8个遗传分化显著的种群集群。与"存在3个异域分布物种"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遗传集群之间的差异。隔离与迁移（IM）模型显示，当前主要陆块间存在持续的基因流。在冰期时期，当前分离的陆块会因海平面下降而相连，沿海岸线扩张与收缩的区域为种群扩散提供了可能，因此这类基因流得以发生。综上，更新世的气候波动对孙达库按蚊广义种的多样性而言，是起到同质化作用而非推动分化的演化动力。