Landscape genetics of insect-pollinated forest herbs in changing agricultural landscapes

农业景观中的大多数生物多样性可以在半自然栖息地的小块中找到。然而，许多物种不适应生活在小的栖息地岛屿上。例如，典型的落叶森林草本植物是在景观或多或少被持续森林覆盖的时候进化出来的。为了在栖息地碎片中长期生存，栖息地专家需要定期交换个体或本地种群之间的散布孢子，这在元种群中很常见。森林草本植物是否以及在什么情况下形成集合种群尚不清楚。由于植物种群之间的基因流动是通过种子和花粉的传播而不是植物的活跃运动进行的，这些问题的答案将取决于相关的种子和花粉传播载体如何受到景观结构的影响。在这个项目中，我们将结合种群遗传学和景观生态学的方法，在农业景观的背景下研究森林草本植物及其相关传粉者的区域种群遗传结构。我们有三个主要目标：(1)我们将阐明草本植物的交配策略在塑造区域种群遗传结构中的作用(自交与异交；相关传粉者物种的短与长觅食距离)。(2)确定景观基质对区域种群遗传结构的影响。特别是，我们感兴趣的是一些作物物种的作用，这些物种预计会影响哺乳动物(玉米)的种子传播或昆虫(油菜)的花粉转移，以及可能作为走廊(例如树篱)或屏障(例如道路)的线性景观元素。(3)我们将在现在的植物种群遗传结构中发现过去的遗产。在这里，我们预计目前的种群遗传结构将比目前的景观结构更好地反映几十年前的景观结构。我们的研究将集中在三种森林草本植物上，将在分布在欧洲西北部的七种不同的农业景观中进行调查。此外，我们将研究两个相关传粉物种的种群遗传结构，一个是大黄蜂，一个是飞蝇，在三个景观中。遗传分析将包括基于微卫星标记的植物和传粉者个体的基因分型，量化当代花粉介导的基因流的父子关系分析，将大黄蜂工蜂分配到群体中的同胞关系重建，以及基于联合理论的历史基因流动率估计。景观生态学方法将包括绘制当前和历史的景观构成和配置图，分别计算植物种群周围和之间的圆形地带和景观带的景观度量，量化自1950年以来的土地利用变化，并根据景观(变化)度量建立种群遗传度量的模型。

Most of the biodiversity in agricultural landscapes can be found in small fragments of semi-natural habitats. However, many species are not adapted to live in small habitat islands. For instance, typical deciduous forest herbs evolved during times when the landscape was more or less continuously forested. Long-term survival in habitat fragments requires habitat specialists to exchange regularly individuals or diaspores among local populations, as common in meta-populations. Whether at all and under which circumstances forest herbs form a metapopulation is unclear. Since gene flow among plant populations occurs via seed and pollen dispersal rather than active plant movement, the answer to these questions will depend on how the associated seed and pollen dispersal vectors are influenced by the landscape structure.In this project, we will combine population genetic and landscape ecological approaches to study the regional population genetic structure of forest herbs and their associated pollinators in the context of agricultural landscapes. We have three main objectives: (1) We will elucidate the role of the herb's mating strategy in shaping the regional population genetic structure (selfing vs. outcrossing; short vs. long forage distance of the associated pollinator species). (2) We will determine the effects of the landscape matrix on the regional population genetic structure. In particular, we are interested in the role of some crop species that are expected to influence seed dispersal by mammals (maize) or pollen transfer by insects (oilseed rape) and in linear landscape elements that may act as corridor (e.g., hedgerows) or barrier (e.g., roads). (3) We will detect legacies of the past in present-day plant population genetic structures. Here, we expect the current population genetic structure to reflect the landscape structure of some decades ago better than the current landscape structure.Our research will focus on three forest herb species, which will be surveyed in seven different agricultural landscapes spread across northwestern Europe. In addition, we will study the population genetic structure of two associated pollinator species, a bumblebee and a hoverfly species, in three of the landscapes. Genetic analyses will comprise amongst others the genotyping of plant and pollinator individuals based on microsatellite markers, paternity analysis to quantify the contemporary pollen-mediated gene flow, sibship reconstruction to assign bumblebee workers to colonies and the estimation of the historical gene flow rates based on coalescent theory. Landscape ecological approaches will include the mapping of the current and historical landscape composition and configuration, the calculation of landscape metrics in circular zones and landscape strips around and between the plant populations, respectively, the quantification of land-use changes since 1950, and the modelling of population genetic measures as a function of landscape(-change) metrics.