Pollination ecology and genetic population structure of three species of cacao (Theobroma spp.) in Bolivia

热带雨林树种的特点是种群密度低，同种个体之间的距离很大。这种空间分布对基因流，特别是传粉者的树间运动有影响。鉴于目前森林的破碎化，基因流的知识是了解热带树种繁殖成功的基础。在这里，我们建议使用三个下层种可可（可可）在北方玻利维亚作为一个模型系统，比较传粉者组合，交配系统，和模式的基因流在野生和栽培种群，使用不同的树木密度的地块。我们假设，可可属物种的授粉生态不同的物种之间，以及野生和栽培种群之间，传粉者的时空分布主要取决于气候因素，同时开放的花朵的数量，并通过树的人口密度。我们进一步假设，自交和异交之间的比例在不同密度的群体中变化，更高的群体密度，人工授粉和更高的遗传特异性增强授粉成功和坐果。由于授粉和种子传播都依赖动物，种群遗传结构可能是中等的。除了实地研究，包括传粉昆虫捕获研究和坐果实验，我们将使用直接和间接的分子方法来评估基因流，如评估空间遗传结构和亲子分析，以遵循这些假设。我们的研究结果是普遍感兴趣的了解交配系统在热带森林生态系统的演变。

Tropical rainforest tree species are characterized by low population densities, with great distances between conspecific individuals. This spatial distribution has consequences for gene flow, especially for the intertree movement of pollinators. In view of ongoing forest fragmentation, knowledge on gene flow is elementary for comprehending the reproductive success in tropical tree species. Here, we propose to use three understorey species of Theobroma (cacao) in northern Bolivia as a model system to compare pollinator assemblages, mating systems, and patterns of gene flow in wild and cultivated populations, using plots of different tree density. We assume that the pollination ecology of Theobroma species differs between species as well as between wild and cultivated populations, and that the spatial and temporal distribution of pollinators is mainly determined by climatic factors, by the number of simultaneously open flowers, and by tree population density. We further hypothesize that the ratio between selfing and outcrossing varies in differently dense populations, and that higher population density, artificial pollination and higher genetic distinctness enhance pollination success and fruit set. The population genetic structure will probably be moderate, due to the dependence on animals for both, pollination and seed dispersal. Besides field studies encompassing pollinator capture studies and fruit set experiments, we will use direct and indirect molecular methods for assessing gene flow such as assessment of spatial genetic structure and parentage analysis to follow these assumptions. Our results are of general interest for understanding the evolution of mating systems in tropical forest ecosystems.