Sexual dimorphism in lizards arises from the dynamic interplay between natural and sexual selection, manifesting in divergent morphological, chromatic, and functional traits across taxa. This study investigated the extent and structure of sexual dimorphism in the mountain dragon (Diploderma vela), a protected species endemic to the arid river valleys of the upper Lancang River basin in southwestern China. A total of 94 individuals were assessed for nine morphological parameters, maximum bite force capacity, and body coloration across 15 anatomical regions. Results revealed pronounced male-biased dimorphism was present in this lizard, with males exhibiting larger head dimensions, elongated limbs and tails, and stronger bite force capacity than females, consistent with patterns driven by intrasexual selection. Marked sexual dichromatism was observed in the throat, lateral body surfaces, and dorsal markings (both light and dark). Bite force scaled positively with head dimensions but exhibited distinct sex-specific predictors, revealing divergent selective trajectories. In males, bite capacity was most significantly associated with head width, whereas in females, head length emerged as the primary determinant. This sexually differentiated architecture underscores the complex interplay between sexual and natural selection in shaping functional traits. These findings offer a mechanistic framework for understanding trait evolution in D. vela and provide a critical empirical foundation for conservation strategies tailored to the ecological and evolutionary dynamics of this restricted-range species.

Understanding how closely related taxa diverge and persist in spatial contact zones is central to explaining biodiversity dynamics. Habitat heterogeneity can promote lineage divergence through disruptive ecological pressures that favor differentiation in morphology, behavior, and ecological traits. This study focused on two closely related parapatric species, Diploderma yangi and D. slowinskii, which occupy contrasting microhabitats across the Nujiang River Basin in western China. The analysis integrated environmental, morphological, and dietary datasets to elucidate how niche partitioning stabilizes species boundaries in a landscape characterized by pronounced heterogeneity. Altitudinal gradients and microhabitat features, including substrate composition and stone size, clearly delineated their distributions. The arboreal species, D. slowinskii, exhibited a larger overall body size, elongated limbs, and an extended tail relative to the saxicolous-terrestrial taxon D. yangi, consistent with biomechanical demands of climbing rather than ground‑based movement. Despite both taxa functioning as arthropod generalists, trophic profiles diverged markedly: D. yangi predominantly consumed smaller prey items, whereas D. slowinskii targeted larger arthropods, reflecting differentiation in trophic niche breadth driven by habitat-specific prey structure. These results suggest that strong environmental gradients within a narrow contact zone generate persistent ecological divergence, with coordinated shifts in habitat use, morphology, and diet. Collectively, this study supports a mechanistic model of parapatric diversification and underscores the role of fine‑scale habitat complexity in sustaining high species richness across the Hengduan Mountains.

The gut microbiota contributes to host health by facilitating nutrient uptake, digestion, energy metabolism, intestinal development, vitamin synthesis, and immunomodulation, and plays an important role in the growth and reproduction of the animal itself. Considering the paucity of research on the gut microbiota of wild snakes, this study focused on bamboo pitviper (Viridovipera stejnegeri) populations from Anhui, Guizhou, and Hunan, with multiple fecal samples collected from each population (six, five, and three, respectively). Total microbial DNA was extracted from the fecal samples using metagenomic next-generation sequencing and differences in gut microbial composition, abundance, and carbohydrate-active enzymes (CAZymes) were analyzed among the three populations. Results showed no significant variance in the α-diversity of the gut microbes across the three populations, while principal coordinate analysis revealed significant differences in gut microbe composition. The four most abundant phyla in the gut microbiota of V. stejnegeri were Pseudomonadota, Bacteroidota, Actinomycetota, and Bacillota, while the four most abundant genera were Salmonella, Citrobacter, Bacteroides, and Yokenella. Linear discriminant analysis effect size demonstrated notable differences in gut microbial abundance among the three populations. Marked differences in CAZyme abundance were also observed across the microbial communities. Future studies should incorporate diverse ecological factors to evaluate their influence on the composition and function of gut microbiota. This integrated approach, alongside detailed functional analysis of microbiota, should deepen our understanding of gut microbial dynamics in wild snakes.