Phylogeny of the island archipelago frog genus Sanguirana: Another endemic Philippine radiation that diversified ‘Out-of-Palawan’

• Philippine endemic Sanguirana colonized the archipelago via the Palawan microcontinent.
• Repeated bouts of overwater dispersal appear to be associated with most speciation events.
• Radiation consists of both single-island endemics and islands with multiple sympatric species.
• Differences between mtDNA and nDNA partitions suggest deep coalescence of gene lineages.

Recent higher-level frog phylogenetic analyses have included a few members of the endemic Philippine frog genus Sanguirana. Although the monophyly of the group has never been disputed, the recent phylogenetically-supported inclusion of the Palawan Wood Frog (Sanguirana sanguinea) in this clade was highly unexpected. In addition, species boundaries and relationships remain unclear and new species continue to be discovered. We estimate the phylogeny for this endemic Philippine genus using two mitochondrial gene regions and six nuclear loci and complete sampling for all known species. We use a time-calibrated Bayesian estimate of phylogeny and model-testing approach to biogeographic inference to infer ancestral areas and probable means of diversification. These analyses identify Sanguirana as an additional clade for which the ‘Out-of-Palawan’ biogeographic scenario is unambiguously preferred. This study lends additional support to recent work suggesting that a substantial portion of Philippine vertebrate megadiversity originated via colonization of the archipelago from the Palawan microcontinent, with subsequent invasion of oceanic islands (e.g., range expansion over Huxley’s Modification of Wallace’s Line), numerous instances of overwater dispersal, and geographic radiation across the archipelago.

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