title: Repeated landmass reformation limits diversification in the widespread littoral zone mosquito Anopheles sundaicus sensu lato in the Indo-Oriental Region.
abstract: 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.
authors.affiliation: Parasite Genomics Group, Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, CB10 1SA, UK.
authors.forename: Magdalena
authors.initials: M
authors.lastname: Zarowiecki
authors.forename: Yvonne-Marie
authors.initials: YM
authors.lastname: Linton
authors.forename: Rory J
authors.initials: RJ
authors.lastname: Post
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Bangs
authors.forename: Pe Than
authors.initials: PT
authors.lastname: Htun
authors.forename: Thaung
authors.initials: T
authors.lastname: Hlaing
authors.forename: Chang Moh
authors.initials: CM
authors.lastname: Seng
authors.forename: Visut
authors.initials: V
authors.lastname: Baimai
authors.forename: Trung Ho
authors.initials: TH
authors.lastname: Ding
authors.forename: Tho
authors.initials: T
authors.lastname: Sochantha
authors.forename: Catherine
authors.initials: C
authors.lastname: Walton
mesh_terms: D000220:Adaptation, Biological / Q000235:genetics; D000818:Animals; D000852:Anopheles / Q000235:genetics*; D001210:Asia, Southeastern; D002980:Climate; D004272:DNA, Mitochondrial / Q000235:genetics; D021903:DNA, Ribosomal Spacer / Q000235:genetics; D017753:Ecosystem; D051456:Gene Flow; D049810:Genetic Speciation; D008359:Mannose-6-Phosphate Isomerase / Q000235:genetics; D008957:Models, Genetic; D008969:Molecular Sequence Data; D017422:Sequence Analysis, DNA
chemical_list: D004272:DNA, Mitochondrial; D021903:DNA, Ribosomal Spacer; D008359:Mannose-6-Phosphate Isomerase
keywords: Anopheles epiroticus; biogeography; isolation with migration; mannose phosphate isomerase (Mpi); speciation; vicariance