Departamento de Biologia, Universidade Federal de Lavras, CP 3037, Lavras, Minas Gerais, CEP 37200-000, Brazil.
Department of Natural Resources and Environmental Sciences, University of Illinois at Urbana-Champaign, Turner Hall, 1102 S Goodwin Avenue, Urbana, IL, USA.
Oecologia. 2020 May;193(1):189-198. doi: 10.1007/s00442-020-04662-4. Epub 2020 May 13.
While functional traits can facilitate or constrain interactions between pair of species in ecological communities, relative abundances regulate the probabilities of encounter among individuals. However, the relative importance of traits and relative abundances for the role species play in seed dispersion networks remains poorly explored. Here, we analyzed 20 Neotropical seed dispersal networks distributed from Mexico to southeastern Brazil to evaluate how relative abundance and functional traits influence bat species' roles in seed dispersal networks. We tested how bat relative abundance and traits relate to species contribution to between-module (c metric) and within-module connectivity (z metric) and their position and potential to mediate indirect effects between species (betweenness centrality). Our results indicate that relative abundance is the main determinant of the role bats play in the networks, while traits such as aspect ratio show modest yet statistically significant importance in predicting specific roles. Moreover, all seed dispersal networks presented two or three superabundant obligatory frugivore species that interacted with a high number of plants. The modest influence of the functional traits on species' roles is likely related to the low variation of morphological traits related to foraging ecology, which reduces the chances of morphological mismatching between consumers and resources in the system. In this scenario, abundant bats have higher chances of encountering resources and being capable of consuming them which leads such species to play critical roles in the community by acting as module hubs and network connectors.
虽然功能特征可以促进或限制生态群落中物种对之间的相互作用，但相对丰度调节了个体之间相遇的概率。然而，对于物种在种子扩散网络中所扮演的角色，特征和相对丰度的相对重要性仍未得到充分探索。在这里，我们分析了分布在从墨西哥到巴西东南部的 20 个新热带种子扩散网络，以评估蝙蝠相对丰度和功能特征如何影响其在种子扩散网络中的作用。我们测试了蝙蝠相对丰度和特征与物种对模块间（c 度量）和模块内连接性（z 度量）的贡献以及它们在物种间间接效应（中间中心性）中的位置和潜在作用之间的关系。我们的结果表明，相对丰度是蝙蝠在网络中作用的主要决定因素，而长宽比等特征在预测特定作用方面具有适度但具有统计学意义的重要性。此外，所有的种子扩散网络都有两个或三个超级丰富的专性食果蝙蝠物种，与大量的植物相互作用。功能特征对物种作用的影响较小，这可能与觅食生态相关的形态特征变化较小有关，这降低了系统中消费者和资源之间形态不匹配的可能性。在这种情况下，丰富的蝙蝠有更高的机会遇到资源并能够消耗它们，这使得这些物种通过充当模块枢纽和网络连接器在群落中发挥关键作用。
