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High rates of hybridisation reveal fragile reproductive barriers between endangered Australian sea snakes

Sanders, Kate L., Rasmussen, Arne R. and Guinea, Michael L. (2014). High rates of hybridisation reveal fragile reproductive barriers between endangered Australian sea snakes. Biological Conservation,171:200-208.

Document type: Journal Article
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IRMA ID 84376995xPUB20
Title High rates of hybridisation reveal fragile reproductive barriers between endangered Australian sea snakes
Author Sanders, Kate L.
Rasmussen, Arne R.
Guinea, Michael L.
Journal Name Biological Conservation
Publication Date 2014
Volume Number 171
ISSN 0006-3207   (check CDU catalogue open catalogue search in new window)
Scopus ID 2-s2.0-84893925194
Start Page 200
End Page 208
Total Pages 9
Place of Publication Netherlands
Publisher Elsevier BV
HERDC Category C1 - Journal Article (DIISR)
Abstract The viviparous sea snakes include 62 ecologically diverse species, many of which are of very recent evolutionary origin and have overlapping distributions. Peak sea snake diversity and endemism is recorded from the isolated emergent reefs of the Timor Sea in Northwest Australia. However, nine species have disappeared from Ashmore, the largest of these reefs, over the last 15 years, including two critically endangered Aipysurus species that have also disappeared from neighbouring Hibernia Reef. A third Timor Sea endemic, Aipysurusfuscus, is now known only from Scott and Hibernia reefs, where it coexists with closely related and locally abundant Aipysuruslaevis. We analysed microsatellite markers for A. fuscus and A. laevis sampled across four Timor Sea reefs to assess evidence for recent inter-specific gene flow and historical introgression. Our data fit an Isolation–Migration model, which showed significant and asymmetrical levels of gene flow following species divergence, and highest rates of introgression from the large A. laevis population into the much smaller A. fuscus population. Population assignment analyses recovered two ancestral clusters that broadly corresponded to morphological species designations, but revealed high frequencies of hybrids on all four reefs and individuals of pure A. fuscus ancestry only at Scott and (historically) Ashmore. Most unexpectedly, 95% of snakes sampled at Hibernia were hybrids that resembled A. laevis in phenotype, revealing a collapse of reproductive barriers (‘reverse speciation’) at this reef. These results have dire implications for the conservation status of A. fuscus, and highlight the fragility of reproductive barriers in a recent marine radiation.
Keywords Endangered species
Hybridisation
Reverse speciation
Microsatellites
Sea snakes
DOI http://dx.doi.org/10.1016/j.biocon.2014.01.013   (check subscription with CDU E-Gateway service for CDU Staff and Students  check subscription with CDU E-Gateway in new window)
Description for Link Link to publisher's version
URL http://www.sciencedirect.com/science/article/pii/S0006320714000159
 
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