Condition, dispersal, and population connectivity of two butterfly species in agricultural landscapes

由于物种灭绝和人口减少，地球的生物多样性正在下降。近年来，一些研究记录了昆虫的大量减少，特别是在农业景观中。通过减少生物多样性提供的商品和服务，这种损失可能会对生态系统和人类社会产生反馈。虽然有关昆虫大规模减少的证据正在迅速增加，但其根本原因仍存在争议，但迄今为止还没有得到很好的理解。土地利用集约化一再被认为是主要驱动因素，最近的研究表明，昆虫的减少与景观尺度上的农业有关。这意味着栖息地面积和连通性，从而分散和资源可用性的重要作用，迄今可能被低估了。本文以两种具有不同传播能力的蝴蝶（Coenonympha pamphilus和Pieris rapae）为研究对象，重点分析了农业景观中昆虫数量下降的两个重要方面，即(1)传播限制和(2)缺乏成虫食物（花蜜）资源的影响。两者密切相关，因为花蜜在很大程度上促进了蝴蝶的传播，而传播能力将影响在破碎景观中获得这些资源的可能性。将在复制的传统农业景观和（高度分散的）现代农业景观之间进行模式比较，这些景观在土地利用强度和生境网络方面有所不同。我将采用高度集成的方法，结合实地收集、形态学和生理学分析、普通园林实验、GIS分析和精细景观基因组学。后者使研究分散，甚至在小的空间尺度前所未有的严格。我将研究(1)蝴蝶的状况，(2)飞行形态，(3)飞行能力和倾向，(4)种群遗传结构，(5)代谢途径的变化。不同方法的整合将大大提高我们对农业景观中蝴蝶减少的理解。

The Earth’s biodiversity is currently declining through species extinctions and reductions in population abundances. In recent years, several studies documented massive insect declines, in particular in agricultural landscapes. Such losses will likely feedback on ecosystems and human societies alike, through a reduction in the goods and services biodiversity provides. While the evidence for large-scale insect declines is rapidly increasing, the underlying causes are debated but hitherto not well understood. Land-use intensification has been repeatedly suggested to be a major driver, and recent studies show that insect declines are associated with agriculture at the landscape scale. This implies an important and hitherto probably underestimated role of habitat area and connectivity, and thus dispersal and resource availability. Using two butterfly species with contrasting dispersal ability (Coenonympha pamphilus, Pieris rapae), I here focus on two important aspects potentially underlying insect declines in agricultural landscapes, namely the impact of (1) constraints on dispersal and (2) a lack of adult food (nectar) resources. Both are intimately associated, as nectar largely fuels dispersal in butterflies, while dispersal ability will affect the likelihood of reaching such resources in fragmented landscapes. Patterns will be compared among replicated traditional and (highly fragmented) modern agricultural landscapes, differing in land use intensity and habitat networks. I will use a highly integrated approach combining field collections, morphological and physiological analyses, common garden experiments, GIS analyses, and fine-scale landscape genomics. The latter enables investigating dispersal even at small spatial scales with unprecedented rigour. I will investigate (1) butterfly condition, (2) flight morphology, (3) flight capacity and propensity, (4) population genetic structure, and (5) variation in metabolic pathways. The integration of different approaches will considerably enhance our understanding of butterfly declines in agricultural landscapes.