Guerra Tadeu J, Dayrell Roberta L C, Arruda André J, Dáttilo Wesley, Teixido Alberto L, Messeder João V S, Silveira Fernando A O
Departamento de Botânica, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil.
Red de Ecoetología, Instituto de Ecología, A.C, Xalapa, Mexico.
Oecologia. 2017 Oct;185(2):233-243. doi: 10.1007/s00442-017-3943-z. Epub 2017 Sep 5.
The extent of specialization/generalization continuum in fruit-frugivore interactions at the individual level remains poorly explored. Here, we investigated the interactions between the Neotropical treelet Miconia irwinii (Melastomataceae) and its avian seed dispersers in Brazilian campo rupestre. We built an individual-based network to derive plant degree of interaction specialization regarding disperser species. Then, we explored how intraspecific variation in interaction niche breadth relates to fruit availability on individual plants in varying densities of fruiting conspecific neighbors, and how these factors affect the quantity of viable seeds dispersed. We predicted broader interaction niche breadths for individuals with larger fruit crops in denser fruiting neighborhoods. The downscaled network included nine bird species and 15 plants, which varied nearly five-fold in their degree of interaction specialization. We found positive effects of crop size on visitation and fruit removal rates, but not on degree of interaction specialization. Conversely, we found that an increase in the density of conspecific fruiting neighbors both increased visitation rate and reduced plant degree of interaction specialization. We suggest that tracking fruit-rich patches by avian frugivore species is the main driver of density-dependent intraspecific variation in plants' interaction niche breadth. Our study shed some light on the overlooked fitness consequences of intraspecific variation in interaction niches by showing that individuals along the specialization/generalization continuum may have their seed dispersed with similar effectiveness. Our study exemplifies how individual-based networks linking plants to frugivore species that differ in their seed dispersal effectiveness can advance our understanding of intraspecific variation in the outcomes of fruit-frugivore interactions.
在个体层面上，果实与食果动物相互作用中的专业化/泛化连续体的程度仍未得到充分探索。在这里，我们研究了新热带小树米氏红苞藤（野牡丹科）与其在巴西rupestre草原的鸟类种子传播者之间的相互作用。我们构建了一个基于个体的网络，以得出植物在传播者物种方面的相互作用专业化程度。然后，我们探讨了相互作用生态位宽度的种内变异如何与不同密度的结果实同种邻居个体植物上的果实可用性相关，以及这些因素如何影响传播的 viable 种子数量。我们预测，在结果实邻里密度较高的情况下，果实作物较大的个体具有更广泛的相互作用生态位宽度。缩小规模的网络包括9种鸟类和15种植物，它们在相互作用专业化程度上相差近5倍。我们发现作物大小对访问率和果实去除率有积极影响，但对相互作用专业化程度没有影响。相反，我们发现结果实同种邻居密度的增加既提高了访问率，又降低了植物的相互作用专业化程度。我们认为，鸟类食果动物追踪富含果实的斑块是植物相互作用生态位宽度中密度依赖性种内变异的主要驱动因素。我们的研究通过表明沿着专业化/泛化连续体的个体可能以相似的效率传播其种子，揭示了相互作用生态位种内变异被忽视的适合度后果。我们的研究例证了将植物与种子传播效果不同的食果动物物种联系起来的基于个体的网络如何能够推进我们对果实 - 食果动物相互作用结果种内变异的理解。
