A time-calibrated salamander phylogeny including 765 species and 503 genes.

Abstract

Recent time-calibrated amphibian phylogenies agree on the family-level relationships among extant salamanders but had disparate sampling regimes and inferred very different divergence times. For example, a recent phylogenomic study based on 220 nuclear loci had limited taxon sampling (41 species) and estimated relatively young divergence dates, whereas a more extensive supermatrix study based on 15 genes and 481 species estimated dates that were 22-45 million years older for major clades. Here, we combined phylogenomic and supermatrix approaches to estimate the largest salamander phylogeny to date based on molecular markers. Our matrix contained 765 salamander species and 503 genes (with 92.3% missing data overall). We included 284 more species than the previous largest salamander phylogeny (59% increase) and sampled approximately 93% of all currently described salamander species. Our dating analyses incorporated more than twice as many fossil calibration points within salamanders as previous studies. Maximum-likelihood estimates of tree topology yielded family-level relationships that were consistent with earlier studies. Nearly all species were placed in the expected genera, despite extensive missing data in many species. Bootstrap support was generally high across the tree but was poor in some clades where sampling of genes was limited (e.g., among some bolitoglossine salamanders). The dating analyses yielded age estimates for major clades that were generally intermediate between those from the previous phylogenomic and supermatrix analyses. We also provide a set of 200 time-calibrated trees for use in comparative analyses.