Research Article

Conservation Genetics

, Volume 13, Issue 1, pp 99-115

First online:

Pleistocene isolation, secondary introgression and restricted contemporary gene flow in the pig-eye shark, Carcharhinus amboinensis across northern Australia

  • B. J. TillettAffiliated withResearch Institute for the Environment and Livelihoods, Charles Darwin UniversityAustralian Institute of Marine Science, Arafura Timor Research FacilityTropical Rivers and Coastal Knowledge Research Hub, Charles Darwin UniversityMolecular Fisheries Laboratory, Queensland Department of Employment, Economic Development and Innovation Email author 
  • , M. G. MeekanAffiliated withAustralian Institute of Marine Science, Arafura Timor Research FacilityAustralian Institute of Marine Science, UWA Ocean Sciences Centre (MO96)
  • , D. BroderickAffiliated withMolecular Fisheries Laboratory, Queensland Department of Employment, Economic Development and Innovation
  • , I. C. FieldAffiliated withResearch Institute for the Environment and Livelihoods, Charles Darwin UniversityAustralian Institute of Marine Science, Arafura Timor Research FacilityMarine Mammal Research Group, Graduate School of The Environment, Macquarie University
  • , G. CliffAffiliated withKwaZulu-Natal Sharks Board
  • , J. R. OvendenAffiliated withMolecular Fisheries Laboratory, Queensland Department of Employment, Economic Development and Innovation

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Abstract

We examine the structure and phylogeography of the pig-eye shark (Carcharhinus amboinensis) common in shallow coastal environments in northern Australia using two types of genetic markers, two mitochondrial (control region and NADH hydrogenase 4) and two nuclear (microsatellite and Rag 1) DNA. Two populations were defined within northern Australia on the basis of mitochondrial DNA evidence, but this result was not supported by nuclear microsatellite or Rag 1 markers. One possibility for this structure might be sex-specific behaviours such as female philopatry, although we argue it is doubtful that sufficient time has elapsed for any potential signatures from this behaviour to be expressed in nuclear markers. It is more likely that the observed pattern represents ancient populations repeatedly isolated and connected during episodic sea level changes during the Pleistocene epoch, until current day with restricted contemporary gene flow maintaining population genetic structure. Our results show the need for an understanding of both the history and ecology of a species in order to interpret patterns in genetic structure.

Keywords

Pleistocene Secondary introgression Predator Carcharhinus spp. Genetic structure North Australia