Understanding the factors that regulate geographical variation in species richness has been one of the fundamental questions in ecology for decades, but our knowledge of the cause of geographical variation in species richness remains poor. This is particularly true for herpetofaunas (including amphibians and reptiles). Here, using correlation and regression analyses, we examine the relationship of herpetofaunal species richness in 245 localities across China with 30 environmental factors, which include nearly all major environmental factors that are considered to explain broad-scale species richness gradients in such theories as ambient energy, water Áenergy dynamics, productivity, habitat heterogeneity, and climatic stability. We found that the species richness of amphibians and reptiles is moderately to strongly correlated with most of the environmental variables examined, and that the best fit models, which include explanatory variables of temperature, precipitation, net primary productivity, minimum elevation, and range in elevation, explain ca 70% the variance in species richness for both amphibians and reptiles after accounting for sample area. Although water and temperature are important explanatory variables to both amphibians and reptiles, water variables explain more variance in amphibian species richness than in reptile species richness whereas temperature variables explain more variance in reptile species richness than in amphibian species richness, which is consistent with different physiological requirements of the two groups of organisms.

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Understanding the factors that regulate geographical variation in species richness has been one of the fundamental questions in ecology for decades, but our knowledge of the cause of geographical variation in species richness remains poor. This is particularly true for herpetofaunas (including amphibians and reptiles). Here, using correlation and regression analyses, we examine the relationship of herpetofaunal species richness in 245 localities across China with 30 environmental factors, which include nearly all major environmental factors that are considered to explain broad-scale species richness gradients in such theories as ambient energy, water Áenergy dynamics, productivity, habitat heterogeneity, and climatic stability. We found that the species richness of amphibians and reptiles is moderately to strongly correlated with most of the environmental variables examined, and that the best fit models, which include explanatory variables of temperature, precipitation, net primary productivity, minimum elevation, and range in elevation, explain ca 70% the variance in species richness for both amphibians and reptiles after accounting for sample area. Although water and temperature are important explanatory variables to both amphibians and reptiles, water variables explain more variance in amphibian species richness than in reptile species richness whereas temperature variables explain more variance in reptile species richness than in amphibian species richness, which is consistent with different physiological requirements of the two groups of organisms.

Copper (Cu) is a heavy metal which is being used widely in the industry and agriculture. However, the overuse of Cu makes it a common environmental pollutant. In order to investigate the testicular toxicity of Cu, the pigs were divided into three groups and were given Cu at 10 (control), 125, and 250 mg/kg body weight, respectively. The feeding period was 80 days. Serum hormone results showed that Cu exposure decreased the concentrations of follicular stimulating hormone (FSH) and luteinizing hormone (LH) and increased the concentration of thyroxine (T4). Meanwhile, Cu exposure upregulated the expression of Cu transporter mRNA (Slc31a1, ATP7A, and ATP7B) in the testis, leading to increase in testicular Cu and led to spermatogenesis disorder. The Cu exposure led to an increased expression of antioxidant-related mRNA (Gpx4, TRX, HO-1, SOD1, SOD2, SOD3, CAT), along with increase in the MDA concentration in the testis. In LG group, the ROS in the testis was significantly increased. Furthermore, the apoptotic-related mRNA (Caspase3, Caspase8, Caspase9, Bax, Cytc, Bak1, APAF1, p53) and protein (Active Caspase3) and the autophagy-related mRNA (Beclin1, ATG5, LC3, and LC3B) expression increased after Cu exposure. The mitochondrial membrane potential in the testicular tissue decreased, while the number of apoptotic cells increased, as a result of oxidative stress. Overall, our study indicated that the Cu exposure promotes testicular apoptosis and autophagy by mediating oxidative stress, which is considered as the key mechanism causing testicular degeneration as well as dysfunction.