From Antarctica or Asia? New colonization scenario for Australian-New Guinean narrow mouth toads suggested from the findings on a mysterious genus Gastrophrynoides
1 Institute for Amphibian Biology, Graduate School of Science, Hiroshima University, Hiroshima, 739-8526, Japan
2 Graduate School of Human and Environmental Studies, Kyoto University, Kyoto 606-8501, Japan
3 Institute of Biological Sciences, Faculty of Science, University of Malaya, Kuala Lumpur, 50603, Malaysia
4 Institute for Environment and Development (LESTARI), Universiti Kebangsaan Malaysia, UKM Bangi, Selangor, 43600, Malaysia
5 Faculty of Science and Technology, Universiti Kebangsaan Malaysia, UKM Bangi, Selangor, 43600, Malaysia
6 Institute for Tropical Biology and Conservation, University Malaysia Sabah, Kota Kinabalu, Sabah, 88999, Malaysia
7 3-6-15 Hikarigaoka, Munakata, Fukuoka, 811-3403, Japan
8 Museum Zoologicum Bogoriense, Research Center for Biology, Indonesian Institute of Sciences, Gedung Widyasatwaloka, Jalan Raya Jakarta Bogor km 46, Cibinong, West Java, Indonesia
BMC Evolutionary Biology 2011, 11:175 doi:10.1186/1471-2148-11-175Published: 21 June 2011
Microhylidae is a geographically widespread family of anurans. Although several extensive molecular analyses have attempted to elucidate their subfamilial relationships, and correlate these with Mesozoic and Cenozoic continental drifts, consensus has not been reached. Further, generic level relationships have not been well investigated in some microhylid subfamilies, and therefore subfamilial affiliations of some genera are still unclear. To elucidate the phylogenetic positions of two mysterious Asian genera, Gastrophrynoides and Phrynella, and to better understand the trans-continental distributions of microhylid taxa, we performed molecular phylogenetic and dating analyses using the largest molecular dataset applied to these taxa to date.
Six nuclear and two mitochondrial genes (approx. 8 kbp) were sequenced from 22 microhylid frog species representing eight subfamilies. The maximum likelihood and Bayesian analyses could not fully elucidate the subfamilial relationships, suggesting a rapid radiation of these taxa between 85 and 66 million years ago. In contrast, generic relationships of Asian microhylines were generally well resolved.
Our results clearly showed that one of two problematic Asian genera, Phrynella, was nested in the clade of the Asian subfamily Microhylinae. By contrast, Gastrophrynoides occupied the most basal position of the Australian-New Guinean subfamily Asterophryinae. The estimated divergence of Gastrophrynoides from other asterophryine was unexpectedly around 48 million years ago. Although a colonization scenario via Antarctica to the Australian-New Guinean landmass has been suggested for Asterophryinae, our finding suggested a novel colonization route via Indo-Eurasia.