The brain is among the most energetically costly organs in the vertebrate body, while the size of the brain varies within species. The expensive-tissue hypothesis (ETH) predicts that increasing the size of another costly organ, such as the gut, should compensate for the cost of a small brain. Here, the ETH was tested by analyzing the relationship between brain size variation and digestive tract length in a Swelled-vented frog (Feirana quadranus). A total of 125 individuals across 10 populations ranging from 586 to 1,702 m a.s.l. from the Qinling-Daba Mountains were sampled. With the increase in altitude, the brain size decreases and the digestive tract length increases. Different brain regions do not change their relative size in a consistent manner. The sizes of telencephalon and cerebellum decrease with the increase in altitude, while the olfactory nerve increases its size at high altitudes. However, the olfactory bulb and optic tectum have no significant relationship with altitude. After controlling for snout-vent length (SVL), a significant negative correlation could be found between brain size and digestive tract length in F. quadranus. Therefore, the intraspecific variation of brain size follows the general patterns of ETH in this species. The results suggest that annual mean temperature and annual precipitation are environmental factors influencing the adaptive evolution of brain size and digestive tract length. This study also suggests that food composition, activity times, and habitat complexity are the potential reasons driving the adaptive evolution of brain size and digestive tract length.

Understanding the spatial variation and formation mechanism of biological diversity is a hot topic in ecological studies. Comparing with α diversity, β diversity is more accurate in reflecting community dynamics. During the past decades, β diversity studies usually focused on plants, mammals, and birds. Studies of amphibian β diversity in montane ecosystems, in particular, tadpoles, are still rare. In this study, Mount Emei, located in southwestern China, was selected as the study area. We explored the tadpole β diversity in 18 streams, based on a two-year survey (2018–2019). Our results indicated a high total β diversity in tadpole assemblages, which was determined by both turnover and nestedness processes, and the dominant component was turnover. Both the total β diversity and turnover component were significantly and positively correlated with geographical, elevational, and environmental distances, but no significant relationship was detected between these and the nestedness component. Moreover, the independent contributions of river width, current velocity, and chlorophyll α were larger than that of geographical and elevational distance. Overall, tadpole β diversity was determined by both spatial and environmental factors, while the contribution of environmental factors was larger. Future studies can focus on functional and phylogenetic structures, to better understand the tadpole assembly process.

Reproductive strategies represent a fundamental aspect of life-history evolution and are shaped by environmental heterogeneity across geographic gradients. This study investigated geographic variation in reproductive traits of the swelled vent frog (Nanorana quadranus), a stream-breeding species in China’s Qinling–Daba Mountains. Male reproductive traits were assessed across 10 populations, including testicular asymmetry, relative testis size, sperm morphology, and sperm count. Female reproductive traits were examined in 12 populations, focusing on body mass and absolute fecundity. Results indicated no significant difference in bilateral testicular asymmetry (p > 0.05). Both relative testis size and sperm count increased with latitude. Sperm length correlated positively with testis size. Conversely, female body mass and age increased with altitude, while absolute fecundity was positively correlated with body mass. Environmental analysis revealed that sperm length exhibited significant positive correlations with aspect and seasonal evapotranspiration anomaly (SEA). Relative testis size was regulated by mean diurnal temperature range (Bio2) and precipitation of the wettest month (Bio13). Furthermore, female absolute fecundity correlated with the minimum temperature of the coldest month (Bio6). These findings demonstrate that reproductive strategies in N. quadranus adapt to geographic and environmental gradients, reflecting adaptive plasticity to local ecological pressures. This study advances understanding of amphibian reproductive adaptation and highlights the importance of incorporating environmental factors in life-history research.

The complete mitochondrial genome (mtDNA) of Glyphoglossus yunnanensis (Anura: Microhylidae) consists of a circular DNA molecule of 16,710 bp and encoded 13 protein-coding genes (PCGs), 22 transfer RNA (tRNA) genes, two ribosomal RNA (rRNA) genes, and non-coding regions of an L-strand replication origin and a D-loop region. All PCGs use ATN as the start codon, except for ND2, ATP8, ND4L, and Cytb uses the typical stop codon TAA/TAG; COI, ND6 use AGG; the other PCGs stop with a single T. The length of tRNAs ranged from 66 bp to 73 bp. The Bayesian phylogenetic analysis recovers Glyphoglossus and Microhyla as sister taxa, corroborating previous results.