Hidden hotspots of amphibian biodiversity in China.

Identifying and protecting hotspots of endemism and species richness is crucial for mitigating the global biodiversity crisis. However, our understanding of spatial diversity patterns is far from complete, which severely limits our ability to conserve biodiversity hotspots. Here, we report a comprehensive analysis of amphibian species diversity in China, one of the most species-rich countries on Earth. Our study combines 20 y of field surveys with new molecular analyses of 521 described species and also identifies 100 potential cryptic species. We identify 10 hotspots of amphibian diversity in China, each with exceptional species richness and endemism and with exceptional phylogenetic diversity and phylogenetic endemism (based on a new time-calibrated, species-level phylogeny for Chinese amphibians). These 10 hotspots encompass 59.6% of China's described amphibian species, 49.0% of cryptic species, and 55.6% of species endemic to China. Only four of these 10 hotspots correspond to previously recognized biodiversity hotspots. The six new hotspots include the Nanling Mountains and other mountain ranges in South China. Among the 186 species in the six new hotspots, only 9.7% are well covered by protected areas and most (88.2%) are exposed to high human impacts. Five of the six new hotspots are under very high human pressure and are in urgent need of protection. We also find that patterns of richness in cryptic species are significantly related to those in described species but are not identical.

Effects of hydroxy methionine zinc on growth performance, immune response, antioxidant capacity, and intestinal microbiota of red claw crayfish (Procambarus clarkii).

This study aimed to evaluate the effects of varying zinc (Zn) levels on the growth performance, non-specific immune response, antioxidant capacity, and intestinal microbiota of red claw crayfish (Procambarus clarkii (P. clarkii)). Adopting hydroxy methionine zinc (Zn-MHA) as the Zn source, 180 healthy crayfish with an initial body mass of 6.50 ± 0.05 g were randomly divided into the following five groups: X1 (control group) and groups X2, X3, X4, and X5, which were fed the basal feed supplemented with Zn-MHA with 0, 15, 30, 60, and 90 mg kg-1, respectively. The results indicated that following the addition of various concentrations of Zn-MHA to the diet, the following was observed: Specific growth rate (SGR), weight gain rate (WGR), total protein (TP), total cholesterol (TC), the activities of alkaline phosphatase (AKP), phenoloxidase (PO), total antioxidant capacity (T-AOC), total superoxide dismutase (T-SOD) and catalase (CAT), the expression of CTL, GPX, and CuZn-SOD genes demonstrated a trend of rising and then declining-with a maximum value in group X4-which was significantly higher than that in group X1 (P < 0.05). Zn deposition in the intestine and hepatopancreas, the activity of GSH-PX, and the expression of GSH-PX were increased, exhibiting the highest value in group X5. The malonaldehyde (MDA) content was significantly reduced, with the lowest value in group X4, and the MDA content of the Zn-MHA addition groups were significantly lower than the control group (P < 0.05). In the analysis of the intestinal microbiota of P. clarkii, the number of operational taxonomic units in group X4 was the highest, and the richness and diversity indexes of groups X3 and X4 were significantly higher than those in group X1 (P < 0.05). Meanwhile, the dietary addition of Zn-MHA decreased and increased the relative abundance of Proteobacteria and Tenericutes, respectively. These findings indicate that supplementation of dietary Zn-MHA at an optimum dose of 60 mg kg-1 may effectively improve growth performance, immune response, antioxidant capacity, and intestinal microbiota richness and species diversity in crayfish.

Species richness and endemism pattern of Fagaceae in Southwest China and their environmental interpretation.

How to accurately model species macro-richness patterns and endemism centers is a key focus of biodiversity conservation efforts and a hot biogeographical topic. Southwest China is one of regions with high Fagaceae species richness, the species diversity patterns and driving mechanisms are unclear. In this study, the distribution pattern of species richness (SR), weighted endemism (WE), and corrected weighted endemism (CWE) indices were estimated based on 7258 occurrence points of 161 Fagaceae species in Southwest China using both occurrence-to grid method and species distribution model (SDM). We used the spatial autoregressive (SAR) model to analyze the relationship between diversity indices and environmental factors. Overall, the three SDM-simulated diversity indices were more continuous in values than that of the occurrence-to grid method, though the distributions of those indices obtained by the two methods were similar. The areas with high SR value were mainly distributed in the south edge of Yunnan, north Guangxi and southwest Guangxi (62-89 species). The maximum of WE concentrated in south Yunnan and west Guangxi (1.77-5.02). The highest CWE (0.07-0.17) was found in southeast Tibet, Qinling-Daba Mountains, southwest Guangxi, and southeast Yunnan. The SAR models showed significant effect of precipita-tion in the driest month, standard deviations of seasonal temperature, altitude range and soil organic carbon content on SR. The effects of precipitation in the driest month, standard deviations of seaso-nal temperature, potential evaporation and altitude range on the WE were significant. The precipitation in the driest month, standard deviations of seasonal temperature, historical temperature change, coefficient of variation of enhanced vegetation index and altitude variation had significant effects on the CWE. The R2 of SAR model for SR, WE and CWE was 0.857, 0.733, 0.593, respectively, being higher than that of ordinary least squares (OLS) (R2=0.689, 0.425, 0.422). In conclusion, water availability, climate seasonality, habitat heterogeneity, historical climate change and soil condition were the most important factors limiting the distribution of SR and WE of Fagaceae in Southwest China. The SR and WE centers of Fagaceae were located in south and southeast Yunnan, southwest Guangxi, west Guangxi, Qinling-Daba Mountains, and southeast Tibet, where should be adequately protected.

[Simulation and uncertainty analysis of natural regeneration for pine-oak forests.] / æ¾æ Žæž—å¤©ç„¶æ›´æ–°æ¨¡æ‹Ÿä¸Žä¸ç¡®å®šæ€§åˆ†æž.

The complexity and uncertainty of forest regeneration is crucial for predicting forest ecosystem dynamics. A natural regeneration model of pine-oak forests in Qinling Mountains was constructed with competition, climate and topography factors using Bayesian statistics and global sensitivity analysis (GSA). The alternative models were based on Poisson, negative binomial (NB), zero-inflated Poisson (ZIP), and zero-inflated negative binomial (ZINB) models. According to the uncertainty of model parameter transfer, the analysis results were quantified, and the dominant factors of small probability events affecting forest regeneration were explained. The results showed that the ZINB model was the best one in the simulation of Pinus tabuliformis and Quercus aliena var. acuteserrata. Stand basal area, light interception, slope location and minimum temperature during growing season were the most critical factors affecting natural regeneration of P. tabuliformis, while stand basal area, cosine of aspect interacted with the natural logarithm of elevation, annual mean temperature, and precipitation of the warmest quarter were the most critical factors for Q. aliena var. acuteserrata. The contributions of various factors to the predictive uncertainty were: competition factor (25%) < climate factor (29%) < topography factor (46%) for the simulation of P. tabuliformis regeneration, and climate factor (12%) < competition factor (24%) < topography factor (64%) for the simulation of Q. aliena var. acuteserrata regeneration. The natural regeneration quantity of P. tabuliformis was positively correlated with mean annual temperature and minimum precipitation during growing season, and negatively correlated with the mean temperature in the driest quarter. The natural regeneration quantity of Q. aliena var. acuteserrata was positively correlated with mean annual temperature, minimum precipitation during growing season, precipitation of the warmest quarter, and negatively correlated with mean temperature of the driest quarter. The ZINB model based on Bayesian methods could effectively quantify the major factors driving forest regeneration and interpret the uncertainty propagated from parameters, which was useful for predicting forest regeneration.