Piecing together an integrative taxonomic puzzle: microsatellite, wing shape and aedeagus length analyses of Bactrocera dorsalis s.l. (Diptera: Tephritidae) find no evidence of multiple lineages in a proposed contact zone along the Thai/Malay Peninsula

Authors

  • MATTHEW N. KROSCH,

    Corresponding author
    1. CRC for National Plant Biosecurity, Bruce, A.C.T, Australia
    2. School of Earth, Environmental and Biological Sciences, Queensland University of Technology, Brisbane, Queensland, Australia
      Matthew N. Krosch, School of Earth, Environmental and Biological Sciences, Queensland University of Technology, G.P.O. Box 2434, Brisbane 4000, Queensland, Australia. E-mail: m.krosch@qut.edu.au
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    • Authors MNK and MKS contributed equally to leading this work.

  • MARK K. SCHUTZE,

    1. CRC for National Plant Biosecurity, Bruce, A.C.T, Australia
    2. School of Earth, Environmental and Biological Sciences, Queensland University of Technology, Brisbane, Queensland, Australia
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    • Authors MNK and MKS contributed equally to leading this work.

  • KAREN F. ARMSTRONG,

    1. CRC for National Plant Biosecurity, Bruce, A.C.T, Australia
    2. Bio-Protection Research Centre, Lincoln University, Lincoln, Christchurch, New Zealand
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  • YUVARIN BOONTOP,

    1. School of Earth, Environmental and Biological Sciences, Queensland University of Technology, Brisbane, Queensland, Australia
    2. Plant Protection Research & Development Group, Department of Agriculture, Bangkok, Thailand
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  • LAURA M. BOYKIN,

    1. CRC for National Plant Biosecurity, Bruce, A.C.T, Australia
    2. Bio-Protection Research Centre, Lincoln University, Lincoln, Christchurch, New Zealand
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  • TONI A. CHAPMAN,

    1. CRC for National Plant Biosecurity, Bruce, A.C.T, Australia
    2. NSW Department of Primary Industries, Elizabeth Macarthur Agricultural Institute, Menangle, NSW, Australia
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  • ANNA ENGLEZOU,

    1. CRC for National Plant Biosecurity, Bruce, A.C.T, Australia
    2. NSW Department of Primary Industries, Elizabeth Macarthur Agricultural Institute, Menangle, NSW, Australia
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  • STEPHEN L. CAMERON,

    1. School of Earth, Environmental and Biological Sciences, Queensland University of Technology, Brisbane, Queensland, Australia
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  • ANTHONY R. CLARKE

    1. CRC for National Plant Biosecurity, Bruce, A.C.T, Australia
    2. School of Earth, Environmental and Biological Sciences, Queensland University of Technology, Brisbane, Queensland, Australia
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Matthew N. Krosch, School of Earth, Environmental and Biological Sciences, Queensland University of Technology, G.P.O. Box 2434, Brisbane 4000, Queensland, Australia. E-mail: m.krosch@qut.edu.au

Abstract

Bactrocera dorsalis (Hendel) and B. papayae Drew & Hancock represent a closely related sibling species pair for which the biological species limits are unclear; i.e. it is uncertain if they are truely two biological species, or one biological species which has been incorrectly split taxonomically. The geographical ranges of the two taxa are thought to abut or overlap on or around the Isthmus of Kra, a recognised biogeographic barrier located on the narrowest portion of the Thai Peninsula. We collected fresh material of B. dorsalis s.l. (i.e. B. dorsalis s.s.+ B. papayae) in a north–south transect down the Thai Peninsula, from areas regarded as being exclusively B. dorsalis s.s., across the Kra Isthmus, and into regions regarded as exclusively B. papayae. We carried out microsatellite analyses and took measurements of male genitalia and wing shape, both used previously to separate the taxa. No significant population structuring was found in the microsatellite analysis, consistent with one, predominantly panmictic population. Both morphological datasets showed consistent, clinal variation along the transect, without disjunction. No evidence supported historical vicariance driven by the Isthmus of Kra, and no dataset supported the current taxonomy of two species. Rather, within and across the area of range overlap or abutment between the two species, only continuous morphological and genetic variation was recorded. Recognition that morphological traits previously used to separate these taxa are continuous, and that there is no genetic evidence for population segregation in the region of suspected species overlap, is consistent with a growing body of literature that reports no evidence of biological differentiation between these taxa.

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