上海市城市化梯度上饰纹姬蛙警戒距离的变化

The Changes of Vigilance Distance of the Ornamented Pygmy Frog(Microhyla fissipes)Along an Urban-rural Gradient in Shanghai City

警戒行为是动物对外界风险的一种行为反应,可以提前探测或避开风险以提高生存率,发生警戒行为时动物距外界干扰源的距离则定义为警戒距离。快速城市化发展引起的栖息地改变和人为干扰会对动物的警戒距离产生影响。本研究以饰纹姬蛙(Microhyla fissipes)为研究对象,于2020和2021年的5至7月沿上海市城市化梯度,即市区-近郊-郊区,设置22个研究样点,其中,市区3个、近郊10个、郊区9个,共测量100只饰纹姬蛙的警戒距离,包含市区15只、近郊51只及郊区34只,并基于2 km半径景观中不透水表面(包括建筑和道路)占比定义各研究样点的城市化指数,同时获取各研究样点所在区域的人口密度以定义人类活动强度,探究城市化梯度上两栖动物警戒距离变化与城市化发展引起的栖息地与人类活动强度改变之间的关系。研究结果表明,饰纹姬蛙的警戒距离与城市化指数呈显著负相关,与人口密度也呈负相关,但不显著。本研究认为,两栖动物会通过改变警戒距离适应栖息地城市化过程,研究结果有利于理解两栖类行为对城市化的响应机制。

[Objectives]Vigilance behavior is a kind of animal response to external risks that can detect or avoid dangers in advance to improve survival rate,when it occurs,the distance between animals and external risk source is defined as vigilance distance.Habitat changes and human disturbance caused by rapid urbanization have a significant influence on the vigilance behavior of wildlife.The vigilance distances of populations adapted to urban environments involves changes in behavior and physiology,reflecting phenotypic plasticity or evolution.The objective of this study was to explore the relationships between vigilance distance of Microhyla fissipes and the changes of habitat and human activity intensity caused by urbanization along an urbanization gradient(urban-suburban-rural).[Methods]In this study,we selected M.fissipes as study species,and measured 100 M.fissipes male individuals(urban:15 males;suburban:51 males;rural:34 males)from 22 study sites(urban:3 sites;suburban:10 sites;rural:9 sites)along an urbanization gradient(urban-suburban-rural)between May and August in 2020 and 2021 in Shanghai,China.We used the percentage of impervious surface(including buildings and roads)in each 2 km-radius landscape to represent the urbanization index of these study sites.In addition,we also collected the human population density of each study site to represent human activity intensity.Then we tested the normality of vigilance distance using the Shapiro-Wilk test,and general linear models were used to test the effects of urbanization index and human population density on vigilance distance of M.fissipes in each study site.[Results]We found that the vigilance distance of M.fissipes ranged from 2.8 m to 5.1 m(mean 3.9±0.5 standard deviation)(Table 1).By ranking all possible candidate models based on their Akaike’s information criterion corrected(AICc),urbanization index was the most important predictor in the best model(ΔAICc<2)(Table 2).Model average coefficients showed that vigilance distance of M.fissipes was significantly negatively correlated to urbanization index(P<0.01)and also negatively related to human population density,although not significant(P>0.05)(Table 3).[Conclusion]Our founding suggested that amphibians change the vigilance distance in response to urbanization,which benefits us to understand the response mechanism of amphibian behavior to urbanization.