Phylogeny of the rock wallabies, Petrogale (Marsupialia : Macropodidae). Part II: Detection of hybridisation among macropodines
John A. W. Kirsch A , Olivier Gauthier B C , Antoine Campeau-Péloquin B , Mark D. B. Eldridge D and François-Joseph Lapointe B EA Deceased. Formerly of The University of Wisconsin Zoological Museum, 250 North Mills Street, Madison, WI 53706, USA.
B Département de sciences biologiques, Université de Montréal, C.P. 6128, Succursale Centre-ville, Montréal (Québec), H3C 3J7, Canada.
C Current address: LEMAR UMR 6539 CNRS, IUEM, Université de Bretagne Occidentale, Place Nicolas Copernic, 29280 Plouzané, France.
D Evolutionary Biology Unit, The Australian Museum, 6 College Street, Sydney, NSW 2010, Australia.
E Corresponding author. Email: francois-joseph.lapointe@umontreal.ca
Australian Mammalogy 32(1) 67-75 https://doi.org/10.1071/AM09017
Submitted: 25 June 2009 Accepted: 3 February 2010 Published: 24 March 2010
Abstract
Phylogenetic relationships among rock-wallabies, Petrogale (Marsupialia: Macropodidae), have proven difficult to resolve. Given the documented interspecific hybridisation in the wild and the ease with which hybrids can be bred in captivity, introgression and hybrid speciation are likely explanations for these difficulties. In this paper, an attempt is made at using a phylogenetic approach to identify Petrogale hybrids of known origin. The Hybrid Detection Criterion (HDC) test is applied to DNA–DNA hybridisation data for 15 full species, two natural yard-bred hybrids, and two artificial hybrids from the same pairs of parental species. While the yard-bred hybrids elude detection with this technique, the artificial hybrids, consisting of equimolar mixture of parental extracts, are easily identified. Moreover, splitsgraphs constructed from five pairs of natural and artificial hybrids, including those evaluated with HDC, and their parents show that, in all cases but one, these two kinds of hybrids do not group together. Because the HDC assumes an intermediate phylogenetic position of the hybrid between its postulated parents, it is likely that unequal crossing-over, or another recombination event, affects the results of the test. These conclusions cast some doubt on the possibility of accurately detecting Petrogale hybrids with a phylogenetic approach.
Additional keywords: DNA–DNA hybridisation, Hybrid Detection Criterion, Splitsgraphs.
Acknowledgements
The authors are grateful to all members of the LEMEE for constructive comments on an earlier version of this manuscript. This work was supported by NSERC and FQRNT scholarships to OG, a Faculté des Études supérieures de l’Université de Montréal scholarship to ACP, NSERC grant no. OGP0155251 and FQRNT grant no. PR88559 to FJL, funds from the Australian Research Council and from Macquarie University to MDBE, and by funds for the hybridisation experiments provided by JAWK.
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