Lei Xie

Aim: Disentangling the relative roles of environmental filtering, dispersal limitation, and biotic interactions in shaping island community assembly is a central goal in modern ecology. However, island biogeography studies have rarely quantified biotic filtering or explicitly incorporated functional traits to evaluate how abiotic environments structure communities. To address this gap, we conducted a comprehensive analysis of herpetofauna co‐occurrence patterns and biogeographical variation across islands. Location: Coastal islands of southern Zhejiang, China. Methods: Using herpetofauna survey data collected from 36 coastal islands between October 2021 and September 2025, we characterised island biogeographical features based on island attributes and land‐cover composition. Hierarchical modelling of species communities (HMSC) was applied to partition the effects of environmental variables, spatial structure, and species co‐occurrence on island community assembly. Species traits, phylogenetic relationships and residual covariance were jointly incorporated to infer potential interspecific interactions. Results: Community assembly of island herpetofauna was predominantly driven by environmental filtering. The strength and nature of filtering differed between amphibians and reptiles. Reproductive traits, adult microhabitat preferences, and activity patterns were associated with intercept, distance to mainland, altitude and shape index. After accounting for environmental filtering, residual species associations became weaker. We detected no strong competitive exclusion or facilitative associations, contrary to the expectation of intensified competition on resource‐limited island. Main Conclusions: Our findings show that biogeographic features structure insular herpetofauna communities by acting on species traits, particularly reproductive strategies. The absence of strong species interactions challenges the assumption that competition necessarily intensifies on islands. From a conservation perspective, maintaining environmental heterogeneity that supports functionally diverse life‐history strategies provides a mechanistic foundation for sustaining island herpetofauna, complementing single‐species approaches. This study advances a trait‐based understanding of island community assembly and offers empirical guidance for the conservation of island biodiversity.

Copper is a common pollutant in aquatic environments. Excess copper in water can enter aquatic organisms through respiration, feeding, and adsorption, thereby exerting serious adverse effects on their health. In this study, NEW Genetically Improved Farmed (GIFT) Nile tilapia (Oreochromis niloticus L.) was used to explore the effect of copper on the hepatopancreas and post-exposure recovery. Acute exposure was simulated via an intraperitoneal injection of 3.75 mg Cu²⁺/kg body mass, while physiological saline injections served as the control. Samples were collected on days 1, 7, 14, and 21 post-exposure to evaluate growth performance, histopathological changes, antioxidant enzyme activities, and the expression of oxidative stress-related genes in the hepatopancreas. The results show that body length and mass increased within 21 days of the injection and copper exposure did not significantly affect fish growth. On day 1 after copper injection, numerous vacuoles appeared in hepatopancreatic tissues. On day 14, congestion and obvious hepatic sinusoids were observed. However, on day 21, the tissue structure showed gradually recovery. Compared to the control group, superoxide dismutase (SOD) activity was significantly higher in the exposed group on days 1, 14, and 21, and SOD gene expression was significantly elevated on day 21. Catalase (CAT) activity was significantly higher on day 7, and the expression of the CAT gene increased significantly on days 1 and 21. Glutathione peroxidase (GSH-Px) activity decreased significantly on day 7, whereas GPX gene expression increased significantly at the same time point. No significant difference in acetylcholinesterase (AChE) activity was observed during the experiment. In conclusion, copper administered via intraperitoneal injections induced significant activation of the antioxidant defense system and histopathological damage in the hepatopancreas of tilapia. Although tissue damage gradually recovered over time, the activation of the antioxidant defense system partially persisted. Ultimately, copper exposure did not significantly affect growth indicators such as body length and mass. These results advance our understanding of copper toxicity in farmed fish and provide a scientific reference for safe aquaculture production.

Microplastic (MP) pollution is a major environmental problem, but a comparative study of the toxicological effects of different MPs remains lacking. To explore the toxicological effects of three different microplastics, namely, polypropylene (PP), polystyrene (PS) and polyethylene (PE), Zhenhai brown frog (Rana zhenhaiensis) tadpoles were used as the model animal. The results showed that exposure to PE and PS significantly reduced the metamorphosis rate of the tadpoles. Compared with the control group, the body weight of tadpoles in all MP treatments was significantly reduced compared with that of the control group. In addition, exposure to PE reduced the body length and hind limb length of tadpoles. The number of pigment cells increased and intercellular spaces expanded in the liver tissues of tadpoles receiving PS and PE treatments. The composition and function of the intestinal microbiota in the PP treatment and control groups were similar, whereas between the PS treatment and control, they differed. Liver transcriptome sequencing revealed significant alterations in key genes associated with oxidative stress, energy metabolism, immune response, and apoptosis signaling pathways with PS treatment and PP treatment. In summary, MPs may have harmed tadpoles to varying degrees by interfering with related signaling pathways. The negative effects of PE and PS were greater than those of PP.

Microplastics pollution in freshwater systems is attracting increasing attention. However, our knowledge of its combined toxicity with heavy metals is scarce. In this study, Rana zhenhaiensis was used as the model animal to study the combined poisoning mechanism of cadmium or microplastics on the digestive systems of tadpoles in freshwater. Results showed that the exposure to cadmium and polystyrene increased the mortality and metamorphosis rate of R. zhenhaiensis tadpoles, and delayed their growth and development. Cadmium was detected in the livers and intestines, while polystyrene mainly accumulated in the gills and intestines of tadpoles. The individual exposure of cadmium or polystyrene can cause pathological damage to liver tissue, induce oxidative stress in liver, and change gene expression. Cadmium co-exposure with polystyrene can reduce the cadmium accumulation in the liver. While polystyrene can slightly increase cadmium accumulation in the intestine. Exposure to cadmium and polystyrene altered the abundance and community structure of intestinal microbiota, and polystyrene increased the dysregulation of the gut microbiome. In this study, the combined exposure of microplastics and cadmium had a negative impact on R. zhenhaiensis tadpoles, but the introduction of microplastics on the toxicity of cadmium on the tadpoles needs further investigation, due to the different characteristics of microplastics.

In recent years, nitrate (NO₃-N) pollution in water bodies has been increasing due to the excessive use of nitrogen-based fertilizers. Exposure to NO₃-N during the development of amphibian embryos may have lasting effects on the growth and development of individuals and even threaten their survival, but the toxicity mechanism of NO₃-N in amphibian embryos prior to thyroid morphogenesis remains unclear. In the present study, Bufo gargarizans was selected as the model organism to investigate the toxic effects of 10 mg/L and 100 mg/L NO₃-N exposure (N10 and N100) on amphibian embryos using methimazole (MMI) and exogenous thyroxine (T4) as the reference groups. We found that T4, MMI, N10 and N100 inhibited B. gargarizans embryo growth and development, with MMI and N100 showing the earliest and strongest effects. Transcriptome analysis revealed that MMI and NO₃-N (especially N100) significantly downregulated genes related to thyroid morphogenesis and cholesterol metabolism, while upregulating genes related to inflammation and apoptosis. Together, these results contribute to a deeper understanding of the complex mechanisms by which NO₃-N disrupts B. gargarizans embryonic development, reveal the potential risks of NO₃-N pollution to other aquatic organisms, and provide insights into the conservation of a broader ecosystem.

SOX9 plays a crucial role in the male reproductive system, brain, and kidneys. In this study, we firstly analyzed the complete cDNA sequence and expression patterns for SOX9 from Gekko japonicus SOX9 (gjSOX9), carried out bioinformatic analyses of physiochemical properties, structure, and phylogenetic evolution, and compared these with other members of the gjSOX family. The results indicate that gjSOX9 cDNA comprises 1895 bp with a 1482 bp ORF encoding 494aa. gjSOX9 was not only expressed in various adult tissues but also exhibited a special spatiotemporal expression pattern in gonad tissues. gjSOX9 was predicted to be a hydrophilic nucleoprotein with a characteristic HMG-Box harboring a newly identified unique sequence, “YKYQPRRR”, only present in SOXE members. Among the 20 SOX9 orthologs, gjSOX9 shares the closest genetic relationships with Eublepharis macularius SOX9, Sphacrodactylus townsendi SOX9, and Hemicordylus capensis SOX9. gjSOX9 and gjSOX10 possessed identical physicochemical properties and subcellular locations and were tightly clustered with gjSOX8 in the SOXE group. Sixteen gjSOX family members were divided into six groups: SOXB, C, D, E, F, and H with gjSOX8, 9, and 10 in SOXE among 150 SOX homologs. Collectively, the available data in this study not only facilitate a deep exploration of the functions and molecular regulation mechanisms of the gjSOX9 and gjSOX families in G. japonicus but also contribute to basic research regarding the origin and evolution of SOX9 homologs or even sex-determination mode in reptiles.