What determines gene flow? Effects of landscape, pollinators, selection by mother tree

人类活动造成的自然生境丧失和破碎化是陆地生态系统中普遍存在的现象，被认为是对生物多样性的主要威胁。随着研究水平的提高，我们对破碎化过程及其影响的认识在过去几十年中不断发展。最近的重要研究进展包括长期片段化实验的结果，阐明了片段之间的边缘和周围改变的遗传和人口后果的详细考虑所造成的影响，植物-动物相互作用的片段化和交替，特别是在植物繁殖过程中。在这项研究中，我们专注于森林破碎化对基因流的改变。首先，我们观察了不同生境中传粉昆虫的区系和密度。不同林型间诱集昆虫的丰度和种类组成存在显著差异，表明人为干扰对传粉过程有较大影响。我们的目的是观察主要鸟类传播植物的种子传播。我们在连续和破碎的森林中设置种子陷阱，观察果实生产和种子传播模式，并监测两种森林中的散布密度。发现鸟类密度在很大程度上取决于森林的果实生产而不是森林大小。因此，它是不太可能的碎片本身造成的变化，种子传播，虽然碎片折磨种子传播通过植物物种组成的变化，从而水果生产模式。这一结果与热带森林的研究结果不一致，后者表明，由于破碎化，传粉者的服务能力下降。这种差异可能是因为日本温带森林中的主要扩散者是候鸟，它们只在森林中居住很短的时间，从不强烈依赖森林。

The loss and fragmentation of natural habitats by human activities are pervasive phenomena in terrestrial ecosystems and considered to be major threats to biodiversity With increased levels of research, our understanding of processes involved in fragmentation and their impacts have developed considerablly over last decades. Recent important research advances include results of long-term fragmentation experiments, elucidation of the of influences caused by the creation of edges between fragments and surrounding altered detailed considerations of genetic and demographic consequences fragmentation and alternation of plant-animal interactions especially in plant reproductive processes. In this study we focused on alternation of gene flow by fragmentation of forests. First we observed pollinator fauna and density among different habitats. Window trap catches showed significant differences of abundance and species composition of trapped insects among different forest types, suggesting large changes of pollination processes by human disturbances. We aim observed seed dispersal of major bird-dispersed plants. We set seed traps in continuous and fragmented forests to see fruit production and seed dispersal patterns, and monitor density of disperses in the two forests We found that bird density was largely depended on fruit production of the forests rather than forest size. Thus it is unlikely that fragmentation itself caused changes in seed dispersal, although fragmentation afflicted seed dispersal through changes in plant species composition and thus fruit production patterns. The result is inconsistent with studies from tropical forests, which have indicated maims decline of pollinator service due to fragmentation. The difference may be because major dispersers in temperate forest of Japan are migratory birds, which inhabit a forest for only a short period and never strongly depend on the forest.