Saturday, June 30, 2012

[Herpetology • 2012] Phylogeny and cryptic diversification in Southeast Asian flying geckos of the genus Ptychozoon


Fig. 2. Hypothesized species level relationships of the genus Ptychozoon, illustrated by the maximum clade credibility tree resulting from Bayesian analyses. Nodes supported by ⩾0.95 Bayesian posterior probabilities and ⩾70% ML bootstrap support were considered significantly supported. Numbered and differently colored terminals within P. kuhli correspond to numbered localities on the map and the same color scheme is utilized in Fig. 3. Letters refer to inferred genetic lineages (hypothesized species) from the BPP analyses (Fig. 3).


Abstract
The closed-canopy forests of Southeast Asia are home to an impressive number of vertebrates that have independently evolved morphologies that enhance directed aerial descent (gliding, parachuting). These assemblages include numerous mammal, frog, snake, and lizard clades. Several genera of gekkonid lizards, in particular, have evolved specialized structures such as cutaneous expansions, flaps, and midbody patagia, that enhance lift generation in the context of unique gliding and parachuting locomotion. The genus Ptychozoon represents arguably the most morphologically extreme, highly specialized clade of gliding geckos. Despite their notoriety and celebrated locomotor ability, members of the genus Ptychozoon have never been the subject of a species-level molecular phylogenetic analysis. In this paper, we utilize molecular sequence data from mitochondrial and nuclear gene fragments to estimate the evolutionary relationships of this unique group of flying geckos. Capitalizing on the recent availability of genetic samples for even the rarest of known species, we include the majority of known taxa and use model-based phylogenetic methods to reconstruct their evolutionary history. Because one species, P. kuhli, exhibits an unusually wide distribution coupled with an impressive range of morphological variation, we additionally use intensive phylogeographic/population genetic sampling, phylogenetic network analyses, and Bayesian species delimitation procedures to evaluate this taxon for the possible presence of cryptic evolutionary lineages. Our results suggest that P. kuhli may consist of between five and nine unrecognized, distinct species. Although we do not elevate these lineages to species status here, our findings suggest that lineage diversity in Ptychozoon is likely dramatically underestimated.


Highlights:  ► We estimate phylogenetic relationships of Asian flying geckos of the genus Ptychozoon. ► We use Bayesian species delimitation to assess P. kuhli for putative species boundaries. ► Our results suggest that species diversity of Ptychozoon is substantially underestimated.

Keywords: Canopy specialists; Flying geckos; Parachute geckos; Southeast Asia; Vertebrate gliders



Fig. 1. Sampling for this study, with various symbols representing the species included (key).


Fig. 2. Hypothesized species level relationships of the genus Ptychozoon, illustrated by the maximum clade credibility tree resulting from Bayesian analyses. Nodes supported by ⩾0.95 Bayesian posterior probabilities and ⩾70% ML bootstrap support were considered significantly supported. Numbered and differently colored terminals within P. kuhli correspond to numbered localities on the map and the same color scheme is utilized in Fig. 3. Letters refer to inferred genetic lineages (hypothesized species) from the BPP analyses (Fig. 3).


Fig. 3. SplitsTree networks (Huson and Bryant 2006) (A) for two loci (same number and color scheme as that presented in Fig. 2) and ∗BEAST (v1.6.2; Heled and Drummond 2010) topology (B) with results of Bayesian lineage delimitation analyses inferred by BPP. Posterior probabilities of inferred splits are provided at each node, with ranges representing split probabilities produced by variance in prior settings for ancestral population size and relative divergence times.


2012. Phylogeny and cryptic diversification in Southeast Asian flying geckos. Molecular Phylogenetics and Evolution http://dx.doi.org/10.1016/j.ympev.2012.06.009

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