阿波罗绢蝶种群数量和垂直分布变化及其对气候变暖的响应

Response of Parnassius apollo population and vertical distribution to climate warming

局部气候变暖可能改变适应低温环境物种的分布格局,迫使该物种向高海拔或高纬度地区迁移,导致喜寒的山区物种适生区变小、种群数量减少甚至灭绝。阿波罗绢蝶(Parnassius apollo L.1758)属喜寒物种,在国内仅分布于新疆,且天山西部是其主要分布区。根据近40 a阿波罗绢蝶种群数量及垂直分布调查,结合研究区域——天山西部的果子沟山区的气象资料,采用相关函数分析近40 a来阿波罗绢蝶数量与分布对研究区域温度变化的响应。结果表明:1)研究区域的阿波罗绢蝶种群数量明显下降,2010年种群数量不及1981年的50%,且具有明显的垂直分布特征,80.4%的阿波罗绢蝶集中分布于1600—2100 m的山区,并有向高海拔迁移趋势;2)近40 a研究区域增温趋势显著,冬季增温最为明显,每10 a增温速率为0.350℃;3)阿波罗绢蝶数量与冬季和春季平均温度的相关系数最大,分别为-0.79、-0.77,表明越冬期和孵化期温度对阿波罗绢蝶数量有显著影响;4)滑动序列相关分析表明,阿波罗绢蝶数量对冬季和2月份平均温度变化的响应较明显,随着冬季温度及早春2月份温度升高,负相关系数有增加趋势,说明阿波罗绢蝶在长期进化过程中已适应低温山区环境,冬季温度偏高和早春温度迅速回升都将不有利于阿波罗绢蝶越冬和胚胎发育。

Global climate change and its effects on organisms has caused great concern. This is particularly true for those species in high-altitude and high-latitude environments due to their specialized ecology. Butterflies are one of the most susceptible species to global climate change and good indicators of an ecosystem＇s response to climate variation. The present study used a mountain specialized butterfly Parnassius apollo, only found in Xinjiang, China, as a model system to investigate how its population numbers and vertical distribution changed and how the mountain species responded to the rising temperature during the last forty years （1970--2010）. At a lO-year interval from 1980 （i. e. 1981,1991,2001, 2010）, butterfly count data （numbers and vertical distribution） were collected along the same 6 fixed transect routes （800--3200m asl. ） during suitable weather conditions from July to August in Guozigou, Yili area, which is a part of western Tianshan Mountains. The meteorological data （1970--2010） were obtained from Huoeheng weather station. Results showed that the population of P. apollo has decreased sharply since 1980. The number in 2010 （ 133 individuals） was less than the half of that in 1981 （289 individuals）, and there was a significant difference among elevations （P〈0.01）. Most of P. apollo collected （80.40%） were found at the vertical distribution from 1600m to 2100 m, followed by the range from 2100 m to 2900 m （ 11.36% ）. Only 8.24% of butterflies were found at the range from 1200--1600 m. No P. apollo was found at more than 3000 m or less than 1200 m during the field investigations. There was a trend that P. apollo shifted to higher elevation over the last three decades. The percentages of P. apollo numbers at higher elevations （2100-2700 m） are 7.17% ,8.04% ,8.62% ,12.70% for the year of 1981, 1991, 2001, 2010, respectively. Whereas at lower elevations （1100--1600 m） , P. apollo numbers decreased during the four periods, the percentages being 10.0% , 8.3% , 4.4% , 3.7% for the year of 1981, 1991, 2001, 2010, respectively. Since 1970, the annual temperature has significantly increased by the rate of 0. 199~C per decade. The winter temperature had the fastest rate of 0. 350~C per decade, followed by spring by at the rate of 0. 219~C per decade. Correlation analysis on P. apollo population numbers and annual temperature, seasonal temperatures, and monthly temperatures showed that P. apollo was significantly negative correlated to all three groups of temperatures （ P 〈 0.05 ）, with the highest correlation coefficient to the winter （ -0.79 ） and to February temperatures （ -0.76 ）. The sliding window correlation analyses between 5-year moving average temperatures in winter and Feburary and P. apollo population numbers showed when the temperature rose in winter and February, the correlation coefficient increased. This study revealed the mountain specialized butterfly P. apollo is facing both a decline in abundance and a shift to higher elevation with the rapid climate warming.