A hybrid zone defined by allozymes and ventral colour in Geocrinia rosea (Anura : Myobatrachidae)
Don A. Driscoll A B C and J. Dale Roberts AA School of Animal Biology, University of Western Australia, Nedlands, WA 6009, Australia.
B Current Address: Fenner School of Environment and Society, WK Hancock Building 43, Australian National University, Canberra, ACT 0200, Australia.
C Corresponding author. Email: don.driscoll@anu.edu.au
Australian Journal of Zoology 55(6) 371-376 https://doi.org/10.1071/ZO08020
Submitted: 22 February 2008 Accepted: 20 May 2008 Published: 3 June 2008
Abstract
The frog Geocrinia rosea is highly genetically subdivided with a major genetic division between northern and southern populations. Previous research did not sample a region spanning 12 km between these two populations. We report the distribution of G. rosea in the unsampled area and identify a geographically restricted hybrid zone. Boundaries of genetic groups were defined using two allozyme loci in 13 populations and ventral colouration. G. rosea was not continuously distributed in the area of parapatry. At the only point where the northern and southern groups met, there was a single hybrid population with genotypes demonstrating substantial interbreeding. Colour patterns implied a slightly broader hybrid zone, with four populations showing ventral colour introgression. Northern populations tended to have pink bellies whereas southern populations generally had orange bellies. We conclude that the two groups have diverged in allopatry and have formed a very narrow hybrid zone after range expansion. The magnitude of allozyme divergence between the four currently recognised species in the G. rosea complex is similar to the divergence between northern and southern G. rosea and is much greater than the divergence between other intraspecific groups. Taxonomic revision may therefore be warranted.
Acknowledgements
We thank Mike Johnson, Michelle Stuckey and Caroline Fuery for assistance in the laboratory. The project was funded by the Australian Government through the former Australian Nature Conservation Agency.
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