Impact of landscape fragmentation and climate change on body size variation of bumblebees during the last century

Body size is a key parameter of organism fitness. While the impact of climate change on body size has received increasing attention, the long-term consequences of landscape fragmentation are still poorly known. These two major global threats may potentially induce opposite trends: the decrease of body size in warmer environments (e.g. individuals developing faster) or the selection of larger individuals in fragmented habitats (e.g. large individuals more capable of reaching distant patches). We assessed the relationship between temperature and landscape fragmentation with mean body size during the last century, within four European regions (Austria, Belgium, England and above the Arctic circle in Scandinavia) and among queens of five bumblebee species. At the regional scale, we first analysed the variation over time of body size and the two hypothesised drivers, temperature and landscape fragmentation. Then, at the local landscape scale, we tested whether body size varied according to t...体型是表征生物体适合度（organism fitness）的核心参数。尽管气候变化对生物体体型的影响已受到学界越来越多的关注，但景观破碎化（landscape fragmentation）带来的长期生态效应仍鲜有研究。这两大全球环境威胁可能诱发截然相反的体型变化趋势：在温暖环境中，生物体往往因发育速率加快而体型偏小；而在破碎化栖息地中，自然选择更青睐体型更大的个体——例如体型较大的个体更易抵达遥远的生境斑块。本研究以上世纪欧洲四个区域（奥地利、比利时、英格兰以及斯堪的纳维亚北极圈以北区域）的5种熊蜂的蜂后为研究对象，以平均体型为指标，探究了温度与景观破碎化之间的关联。在区域尺度上，我们首先分析了体型及其两个假说驱动因子（温度与景观破碎化）随时间的变化规律；随后在局地景观尺度上，我们检验了体型是否会依据t……