Patterns Of Species Richness Of Lucanus In China And Habitat Suitability Evaluation

Exploring the geographical distribution pattern of species diversity and influencing factors,and predicting the potential distribution areas of species can provide an important reference for species conservation and management.Lucanus is the most representative branch of Lucanidae.This genus is mainly inhabited in open woodlands with good growth conditions,and the larvae feed on decayed wood.The stag beetle is important saprophytic insects,which is of great significance for indicating the health status of forest ecosystems and maintaining the carbon and nitrogen cycle of forest ecosystems.In the background of global climate change and the deforestation of large areas of the forest,many Lucanus species are facing the problem of habitat fragmentation and even loss.They are resource insects that need to be protected.Species diversity of Lucanus in China is the most abundant.However,there is a lack of domestic research on the resource protection of this genus.Studying the distribution pattern of the genus in China and the environmental factors affecting its distribution will help to improve this situation,as it will provide basic data and theoretical reference for the protection and supervision of such resource insects.In this study,we collected and organized distribution data of 72 Lucanus species,and select four types of environmental factor data(including factors of temperature,precipitation,vegetation,and geography).We used geographic information systems combining with various statistical analysis methods such as species accumulation curves,cluster analysis,correlation analysis,stepwise regression,multiple linear regression,and variation partitioning to analyze the main distribution characteristics and species richness distribution pattern of Lucanus.The independent interpretation of the distribution pattern of Lucanus species diversity of different environmental factors was discussed.We used the maximum entropy model to evaluate the ecological suitability of Lucanus and predict its potential distribution area.The research indicates that(1)In China,the distribution range of Lucanus species across 18~43°N and 85~127°E.72 species of the stag beetle species were known.All species were distributed in oriental realm of China(including the central China,the southern China and the southwest China)apart from Lucanus maculifemoratus dybowski,as this species is distributed across the oriental realm and palaearctic realm(mainly distributed in the palaearctic realm including the north China and the northeast China).Based on the grid of 500 km×500 km,calculations proved that Himalayas was a hotspot area where the species richness of Lucanus was the highest(26 species).Although the species richness of the stag beetle species differs significantly between northern and southern China,the species richness does not show a single decreasing trend on the latitude gradient.Similarly,the richness on the longitude gradient does not show a single decreasing or increasing trend.(2)The regression model on species richness and environmental variables comprised by longitude,latitude,standard error of elevation(STD_DEM),elevation range(DEM),mean diurnal range(B2),isothermality(B3),temperature seasonality(B4),min temperature of coldest month(B6),temperature annual range(B7),precipitation seasonality(B15),and net primary productivity(NPP).Therefore,it can be summarized that the geography,temperature,precipitation,and vegetation factors drove the distribution pattern of Lucanus Species richness in China.The variation partitioning further shows that the independent interpretation of geographical factor is the largest(70%);the temperature factor is next to the geographical factor,and it also occupies an important position;the independent interpretation degree of the longitude and elevation factors are far greater than the latitude.(3)The average test AUC of the MaxEnt model was 0.904,which is between 0.9~1.0.The prediction results of the potential distribution areas of Lucanus in China were highly consistent with the actual distribution.Assessment of habitat was divided into four levels basing on the survival index(p),including non-fitness areas(0 < p < 0.091),low-fitness areas(0.091 < p <0.26),moderately suitable areas(0.26 < p < 0.47),and highly suitable areas(0.47 < p < 0.93),where p is the fitness index.Highly suitable areas and moderately suitable areas are mainly distributed in central China,southwest China and Taiwan island.The suitable area accounts for 31% totally.Highly suitable area,moderately suitable area,and lowly suitable habitats accounted for 4%,11%,and 16%,respectively.It indicated that the Lucanus species are more suitable for habitats in China.The Jackknife method estimated that temperature annual range(B7),annual precipitation(B12),and precipitation of wettest quarter(B16)were relatively important factors affecting the prediction of potential distribution areas.