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in Skipwith, Bi & Oliver, 2019.
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Highlights:
• Ultraconserved elements resolve nearly all problematic relationships of diplodactyloid geckos.
• Phylogenenomic estimates differs greatly from Sanger estimates at species-level rather than reaffirms previously proposed relationships.
• Molecular dating confirms young crown ages of New Caledonian and New Zealand diplodactylids relative to mainland Australian radiations.
• No mass extinction event associated with Eocene-Oligocene cooling detected.
• Tail moprhology suggests that the environment has influenced tail shape extensively.
Abstract
Australasia harbors very high squamate diversity and is a center of endemicity for a number of major lineages. However, despite this diversity, the diplodactyloid geckos of Australia, New Caledonia, and New Zealand (comprised of three endemic families and > 200 species) are the only extant squamates with unequivocal Mesozoic origins in the region. Diplodactyloid geckos also exhibit notable phenotypic and ecological diversity, most strikingly illustrated by the functionally limbless pygopods. Here, we present the first phylogenomic analyses of the pattern and timing of diplodactyloid evolution, based on a dataset of more than 4,000 ultraconserved elements (UCEs) from 180 species. These analyses fully resolve nearly all nodes, including a number of intergeneric relationships that have proven problematic in previous studies. The hypothesis that New Caledonia and New Zealand clades represent independent post-KT boundary colonization events of Tasmantis from Australian ancestors is confirmed. Phylogenetic relationships recovered here further highlight contrasting patterns of diversity, most strikingly between insular and/or morphologically highly derived clades that have diversified rapidly, as opposed to other species poor and phylogenetically divergent relictual lineages on mainland Australia. Our new timetree suggests slightly older branching times than previous analyses and does not find a mass extinction event in the early Cenozoic. Finally, our new phylogeny highlights caudal variation across the clade. Most strikingly, the distinctive leaf-tail morphology shown by one family may in fact be plesiomorphic.
Conclusion:
This study represents the first phylogenomic attempt to address the higher-level relationships of an Australasian group of squamates. Our findings resolve many problematic relationships for a biogeographically unique and ecomorphologically diverse lineage. In so doing they highlight both remarkable phylogenetic relicts and instances of marked and potentially convergent ecomorphological evolution. Our study highlights the power of implementing genome-scale data to address questions in macroevolution, and the need for similar frameworks for other diverse and highly endemic Australasian radiations.
Phillip L. Skipwith, Ke Bi and Paul M. Oliver. 2019. Relicts and Radiations: of An Australasian Lizard Clade with east Gondwanan Origins (Gekkota: Diplodactyloidea). Molecular Phylogenetics and Evolution. In Press. DOI: 10.1016/j.ympev.2019.106589
