Intraspecific body size increases with habitat fragmentation in wild bee pollinators
Intraspecific body size increases with habitat fragmentation in wild bee pollinators
复制标题
野生蜜蜂授粉者的种内体型随着栖息地破碎化而增加
作者：
D. Warzecha;T. Diekötter;V. Wolters;F. Jauker
在现代农业景观中，部分栖息地的破碎化是多栖息地使用者的重要过滤器，降低了当地的分类和功能多样性。有令人信服的证据表明，小型物种比大型物种更容易受到影响。然而，生境破碎化对种内体型分布的影响尚未被研究。目的研究生境破碎化对野生独居蜜蜂种内体型分布的影响，生境破碎化是传粉媒介丧失的主要驱动因素。随后，我们测试了个体体型对授粉服务的影响。方法连续2年在德国中部黑森州22个新建的开花地（0.21 ~ 0.41 ha）取样4种最常见的野蜂1272只。研究地点位于约80公顷的生境破碎化加剧的景观背景下。我们分析了最丰富的物种的花粉负荷。结果两种中型蜜蜂种群的体型随破碎度的增加而增大，表明种内选择具有较高的传播能力。对大多数常见物种进行的花粉分析显示，较大的个体访问了明显较小的植物光谱。因此，生境破碎化可能改变授粉服务，而不一定影响物种丰富度或组成。结论种群水平上的系统体型变化解释了简单群落措施与生态系统功能之间的巨大差异。个体层面的过滤过程需要对当前和未来土地利用变化下的授粉服务目标有更多的了解。
ContextIn modern agricultural landscapes, fragmentation of partial habitats is a significant filter for multi-habitat users, reducing local taxonomic and functional diversity. There is compelling evidence that small species are more susceptible than large species. The impact of habitat fragmentation on intraspecific body-size distribution, however, is yet unexplored.ObjectivesWe tested habitat fragmentation, a major driver of pollinator loss, for its impact on intraspecific body-size distributions of solitary wild-bee species. Subsequently, we tested individual body size for its impact on pollination services.MethodsWe sampled 1272 individuals of the four most common Andrena wild bee species in 22 newly established flowering fields (0.21–0.41 ha) in Hessen, Central Germany, over two consecutive years. Study sites were located in a ca. 80 ha landscape context of increasing habitat fragmentation. We analysed the pollen loads of the most abundant species.ResultsBody size within local populations of the two medium-sized bees increased with fragmentation, suggesting intraspecific selection for higher dispersal capacity. Pollen analysis carried out for the most common species revealed that larger individuals visited a significantly smaller plant spectrum. Habitat fragmentation may thus alter pollination services without necessarily affecting species richness or composition.ConclusionsSystematic body-size variation at the population level thus explains the considerable variability between simple community measures and ecosystem functioning. Filtering processes at the individual level require increased understanding for targeting pollination services under current and future land-use change.