上海地区金线侧褶蛙种群的潜在空间分布格局及其景观连通性

Potential spatial distribution pattern and landscape connectivity of Pelophylax plancyi in Shanghai,China

城市化导致的栖息地破碎和丧失是全球范围内威胁野生动物生存的重要因素。两栖动物是受城市化威胁最严重的陆生脊椎动物类群。研究城市化区域两栖动物空间分布格局,探究影响其片断化小种群间基因交流的景观连通性等问题,有助于我们深入理解城市化对野生动物种群的作用机制及造成的影响,能够为当地生物多样性保护提供理论指导。本研究以上海地区金线侧褶蛙(Pelophylaxplancyi)为研究对象,基于Landsat-8卫星影像,获取上海地区土地利用类型、归一化植被指数(normalized difference vegetation index,NDVI)、地表温度等景观、环境数据。结合野外种群调查,通过最大熵(maximum entropy,MaxEnt)模型得到金线侧褶蛙在本地区的潜在空间分布格局;基于电路理论(Circuitscape)计算各小种群间的扩散阻力距离;结合微卫星位点(simple sequence repeat,SSR)和单核苷酸多态性位点(single nucleotide polymorphism,SNP)计算各小种群间的遗传距离(FST),通过Mantel相关性检验探讨地理距离和阻力距离对各小种群间遗传分化的作用效果。结果显示:(1)金线侧褶蛙栖息地适宜性随城市化水平的增高而显著降低;(2)NDVI是影响其潜在空间分布的主要因素,金线侧褶蛙更倾向于栖息在植被覆盖度较高的区域;(3)遗传距离与地理距离之间没有显著的相关性,但随着景观扩散阻力的增大而显著增大。因此,保护和维持郊区连续栖息地以及市区仍然保留的斑块化栖息地是现阶段保护以金线侧褶蛙为代表的本土两栖动物的首要措施。而通过优化城市景观结构,加强针对不同野生动物类群的廊道建设,促进野生动物小种群间的基因交流,则是实现城市化区域野生动物多样性自维持和长期保护的有效途径。

Aims:Habitat fragmentation and loss caused by urbanization are important factors that threaten the survival of wildlife globally.Urbanization has caused amphibians to become one of the most severely threatened groups of terrestrial vertebrates.Studying the spatial distribution pattern and exploring how landscape connectivity affects the gene flow among fragmented populations of amphibians in urban areas would provide a deeper understanding of the impacts of urbanization on wildlife and offer theoretical guidance for local biodiversity conservation.Methods:In this study,we selected the eastern golden frog(Pelophylax plancyi)as the primary research subject and obtained landscape and environmental data about land cover,normalized difference vegetation index(NDVI)and land surface temperature in the Shanghai region using Landsat-8 satellite images(http://www.gscloud.cn).Combined with the data from field population survey,we employed the maximum entropy(MaxEnt)model to predict the spatial distribution pattern of P.plancyi in the region.We evaluated the potential corridors and calculated the resistance distances between local populations using circuit theory(Circuitscape),and explored the effect of geographical and resistance distance on genetic differentiation among local populations using the Mantel test of each local populations based on the genetic distance(FST)matrices calculated from simple sequence repeat(SSR)and single nucleotide polymorphism(SNP).Results:The habitat suitability of P.plancyi significantly decreased along the rural-to-urban gradient.NDVI was the main factor affecting the MaxEnt modelling and indicated that the P.plancyi prefer to inhabit areas with higher vegetation coverage.There was no significant correlation between genetic distance and geographical distance,while genetic distance increased significantly with the resistance distance.Conclusions:The protection and maintenance of continuous suitable habitats in suburbs and isolated habitat patches in urban areas that still exist is the primary measure of conservation for native amphibians such as P.plancyi.Furthermore,optimizing urban landscape structure,strengthening the construction of corridors suitable for various groups of wildlife,and promoting the gene exchange among local populations are effective methods to achieve the self-sustainment of populations and long-term conservation of biodiversity in urbanized areas.