Abstract Nestedness is a pattern frequently reported for faunal assemblages in fragmented systems. Although nestedness has been documented for a wide range of taxa, it is rarely tested in snake assemblages. To arrive ...Abstract Nestedness is a pattern frequently reported for faunal assemblages in fragmented systems. Although nestedness has been documented for a wide range of taxa, it is rarely tested in snake assemblages. To arrive at robust generalizations about processes and mechanisms structuring island biotas, it is important to examine under-represented taxa such as snakes for the insights they may offer. We tested for the existence of nestedness and underlying causal mechanisms using snake data collected on islands in the Thousand Island Lake, China. We used the line-transect method to survey snake occupancy and abundance on 20 islands during two breeding seasons in 2009 and 2010. We used the recently developed metric WNODF to estimate nestedness. We used Spearman rank correlations to examine the associations of nestedness and habitat variables （area, isolation, and habitat diversity） as well as life-history traits （body size, clutch size, geographical range size and area requirement） related to species extinction and immigration tendencies. Snake assemblages were significantly nested and were shaped by extinction processes mediated through area effects and habitat nestedness. The nestedness of snake assemblages was not due to passive sampling or selective colonization. From a conservation viewpoint, our results indicate that we should protect both the largest island with the most species-rich community and habitat-rich islands to maximize the number of species preserved .展开更多
基金We thank two anonymous reviewers for helpful comments on earlier version of the manuscript. We are grateful to Chunan Forestry Bureau and the Thousand Island Lake National Forest Park for permits necessary to conduct the research. This study was supported by the National Natural Science Foundation of China （Nos. 31100394, 31170397）, the China Postdoctoral Science Foundation （No. 20070411192）, Zhejiang Provincial Postdoctoral Science Foundation, and the Fundamental Research Funds for the Central Universities.
文摘Abstract Nestedness is a pattern frequently reported for faunal assemblages in fragmented systems. Although nestedness has been documented for a wide range of taxa, it is rarely tested in snake assemblages. To arrive at robust generalizations about processes and mechanisms structuring island biotas, it is important to examine under-represented taxa such as snakes for the insights they may offer. We tested for the existence of nestedness and underlying causal mechanisms using snake data collected on islands in the Thousand Island Lake, China. We used the line-transect method to survey snake occupancy and abundance on 20 islands during two breeding seasons in 2009 and 2010. We used the recently developed metric WNODF to estimate nestedness. We used Spearman rank correlations to examine the associations of nestedness and habitat variables （area, isolation, and habitat diversity） as well as life-history traits （body size, clutch size, geographical range size and area requirement） related to species extinction and immigration tendencies. Snake assemblages were significantly nested and were shaped by extinction processes mediated through area effects and habitat nestedness. The nestedness of snake assemblages was not due to passive sampling or selective colonization. From a conservation viewpoint, our results indicate that we should protect both the largest island with the most species-rich community and habitat-rich islands to maximize the number of species preserved .
