Vertical stratification of plant-animal interactions and their impact on pollination and seed dispersal within a single Neotropical plant species

热带雨林中的动植物相互作用对花粉和种子的传播至关重要，因此对植物种群内的基因流动也是至关重要的。最近的研究表明，这些相互作用是垂直分层的：不同森林层的物种组合及其相互作用的频率不同，这反过来可能影响花粉和种子的传播，从而影响基因流动。到目前为止，关于授粉和种子传播的研究大多集中在只在一个地层中提供蜜源和果实资源的植物物种上。在我们的研究中，我们的目标是调查一种从地面到树冠开花的植物物种。我们试图研究涉及授粉和种子跨森林地层传播的动物组合，以及这些相互作用对授粉和种子传播的影响，从而对基因流动的影响。如果不同地层之间的相互作用不同，这将有力地支持传粉者和/或种子传播组合的垂直分层的存在，而不依赖于可用的资源。Marcgravia long gifolia是一种新热带藤本植物，为大量食蜜性和食果性脊椎动物提供从林地到树冠的蜜源和果实资源，是我们理想的研究物种。首先，我们试图获得食蜜性动物和食果性动物在不同地层中与长叶木霉相互作用的详细情况。我们将使用摄像机系统地评估探访率，并通过对白天食果动物的重点观察以及对夜间访问藤本植物花序的食蜜性和食果性蝙蝠的喷雾来补充这一点。其次，我们将调查花蜜和水果的质量和数量是否沿垂直梯度变化，以及这是否与食果者和食蜜者组合的变化有关。第三，我们希望详细研究授粉和种子传播的相互作用及其对基因流动的影响。为了研究种子的传播，我们将通过对一组食果性动物(罗望子和叶口蝙蝠)的行为观察来确定跨森林地层的水果去除率，大致的传播距离。此外，我们将使用微卫星标记来确定异交率以及花粉和种子的传播距离。最后，我们将研究长叶马蹄莲种群内的空间遗传结构，以获得种群内基因流动的总体估计。

Plant-animal interactions in tropical rainforests are crucial for pollen and seed dispersal, and thus, for gene flow within plant populations. Recent studies indicate that these interactions are vertically stratified: species assemblages and the frequencies of their interactions differ among forest strata, which in turn might impact pollen and seed dispersal, and thereby gene flow. So far, most studies on pollination and seed dispersal focused on plant species that provide nectar and fruit resources in only one of the strata. In our study, we aim to investigate a plant species that flowers from ground level up to the canopy. We seek to study the animal assemblages involved in pollination and seed dispersal across forest strata as well as the impact of these interactions on pollination and seed dispersal, and thus, on gene flow. If interactions differed between strata, this would strongly support the existence of a vertical stratification of pollinator and/or seed dispersal assemblages independently of the available resources. Marcgravia longifolia is a Neotropical liana species that provides nectar and fruit resources from the forest floor to the canopy for a large number of nectarivorous and frugivorous vertebrate species, and thereby embodies the perfect study species for our purposes. First, we seek to obtain a detailed picture of the assemblages of nectarivores and frugivores that interact with M. longifolia across strata. We will systematically assess visitation rates with video cameras and complement this with focal observation of diurnal frugivores and with mist netting of nectarivorous and frugivorous bats that visit the liana inflorescences at night. Second, we will investigate whether quality and quantity of nectar and fruits vary along the vertical gradient and whether this correlates to shifts in frugivore and nectarivore assemblages. Third, we want to study in detail pollination and seed dispersal interactions and their impact on gene flow. To study seed dispersal, we will determine fruit removal rates across forest strata, approximate dispersal distances by behavioral observations of a subset of frugivores (tamarins and Phyllostomid bats). Further, we will use microsatellite markers to determine outcrossing rates and pollen and seed dispersal distances. Finally we will examine spatial genetic structure within the Marcgravia longifolia population to obtain an overall estimate for intra-population gene flow.