Rates of climatic niche evolution vary widely across the tree of life and are strongly associated with rates of diversification and the accumulation of species diversity among clades. However, why the climatic niche evolves more rapidly in some lineages than others remains unclear. Variation in life history traits often plays a key role in determining the environmental conditions under which species can survive, and therefore, could impact the rate at which lineages can expand in available climatic niche space. Here, we explore the relationships among life-history variation, climatic niche breadth, and rates of climatic niche evolution. We reconstruct a new phylogeny for the genus Desmognathus, an adaptive radiation of salamanders distributed across eastern North America, based on nuclear and mitochondrial genes. Using this phylogeny, we estimate rates of climatic niche evolution for species with long, short, and no aquatic larval stage. Rates of climatic niche evolution are unrelated to the mean climatic niche breadth of species with different life histories. Instead, we find that the evolution of a short larval period promotes greater exploration of climatic space, leading to increased rates of climatic niche evolution across species having this trait. We propose that morphological and physiological differences associated with variation in larval stage length underlie the heterogeneous ability of lineages to explore climatic niche space. Rapid rates of climatic niche evolution among lineages with short larval periods were an important dimension of the clade’s adaptive radiation and likely contributed to the rapid rate of lineage accumulation following the evolution of an aquatic life history in this clade. Our results show how variation in a key life-history trait can constrain or promote divergence of the climatic niche, leading to variation in rates of climatic niche evolution among lineages.

The following files are included: Desmog_24taxa11loci_concatenated.nex contains the aligned, concatenated DNA sequences for all 11 loci for single exemplars of each species. Partitions are included in a mrbayes block below the DNA sequences. Desmog_24taxa11loci_chronogram.nex is the BEAST chronogram from the concatenated analysis. Desmog_62taxa11loci_alignments.zip contains the phased DNA sequence alignment (nexus format) of each of the 11 loci used in the species tree analysis. Also included is starBEAST_speciestraits.txt which assigns each of the 62 individuals to one of 24 species. Desmog_62taxa11loci_speciestree.nex is the species tree from the *BEAST species tree analysis of 11 loci for 62 individuals of 24 species. Desmog_coords_bioclim_data.xlsx contains tab 1: latitude and longitude for localities of each species and the bioclim variables for those localities, tab 2: snout-vent length (SVL in mm), larval period, and microhabitat of each species. Supplemental_Tables.docx contains tables S1: information on DNA loci and primers, S2: nucleotide substitution models used for each locus in analyses, and S3: specimen/sample information.