We obtained geo-referenced occurrence and climatic data from individual localities for 59 species of terrestrial elapid snakes, used phylogenetic generalized least squares regression to investigate spatial and cladistic patterns of variation in climatic niche breadths, and compared patterns within and across regions and clades to see if they parallel or differ from each other. Specifically, we test (1) whether a species’ climatic niche breadth on a given niche axis relates to its position along that axis, and to its climatic niche breadth on another niche axis, and (2) whether variation in niche breadths among species is explained by within-locality variation in climatic conditions or by among-locality variation. We found that: (1) there is an overall global pattern, and patterns in individual regions or clades generally parallel each other and global patterns; (2) species in warmer environments have narrower temperature niche breadths (TNBs); (3) precipitation niche breadth (PNB) and position are positively related; (4) TNB and PNB are not related; and (5) within-locality variation in climatic conditions explains most variation in TNBs, whereas among-locality variation explains most variation in PNBs. Our results are consistent with those reported for lizards of the families Phrynosomatidae and Varanidae, confirm the importance of within-locality niche breadth to species niche breadth, and show a more important role of among-locality niche breadth in affecting species niche breadth in terrestrial elapids than in lizards.

Monitor lizards (Varanidae) inhabit both the mainland and islands of all geological types and have diversified into an exceptionally wide range of body sizes, thus providing an ideal model for examining the role of mainland versus island in driving species evolution. Here we use phylogenetic comparative methods to examine whether a link exists between body size-driven diversification and body size-frequency distributions in varanid lizards and to test the hypothesis that island lizards differ from mainland species in evolutionary processes, body size, and life-history traits (offspring number and size). We predict that: 1) since body size drives rapid diversification in groups, a link exists between body size-driven diversification and body size-frequency distributions; 2) because of various environments on island, island species will have higher speciation, extinction, and dispersal rates, compared with mainland species; 3) as a response to stronger intraspecific competition, island species will maximize individual ability associated with body size to outcompete closely-related species, and island species will produce smaller clutches of larger eggs to increase offspring quality. Our results confirm that the joint effect of differential macroevolutionary rates shapes the species richness pattern of varanid lizards. There is a link between body size-driven diversification and body size-frequency distributions, and the speciation rate is maximized at medium body sizes. Island species will have higher speciation, equal extinction, and higher dispersal rates compared with mainland species. Smaller clutch size and larger hatchling in the island than in mainland species indicate that offspring quality is more valuable than offspring quantity for island varanids.

We used mitochondrial cytochrome b and ND4 genes and 9 microsatellite loci to determine genetic diversity, population structure, evolutionary history, and migration patterns within the Reeves' butterfly lizard Leiolepis reevesii (Agamidae). Considering molecular-based phylogeographical lineages, we then performed niche equivalency and similarity tests between divergent lineages. Phylogenetic analyses based on mitochondrial DNA (mtDNA) data revealed 2 lineages (A and B) diverging ≈0.84 million years ago and, respectively, restricted to the northern and southern portions of the Wuzhishan and Yinggeling mountain ranges. Lineage B contains individuals from southern Hainan; Lineage A includes individuals from all other localities and can be further divided into 3 clusters according to microsatellite data. The null hypothesis that the 2 lineages shared identical niches was rejected in all niche equivalency tests, indicating niche shifts during genetic divergence. Similarity tests provided evidence of niche conservatism, suggesting that the 2 lineages share more characteristics of their niche spaces than randomly expected. The niche similarity and equivalency tests indicated a complex niche pattern in which both lineages share a main portion of their ecological spaces. The climatic niche of Lineage B represented a marginal and specialized fraction of the entire ecological space of the climatic niche of Lineage A, with warmer conditions. Isolation caused by orogenesis and subsequent niche divergence, together with local adaptation, may have led to genetic differentiation and further lineage sorting in L. reevesii.