González-Zamora Arturo, Arroyo-Rodríguez Víctor, Escobar Federico, Rös Matthias, Oyama Ken, Ibarra-Manríquez Guillermo, Stoner Kathryn E, Chapman Colin A
División de Posgrado, Instituto de Ecología A.C., Xalapa, Veracruz, Mexico.
Centro de Investigaciones en Ecosistemas, Universidad Nacional Autónoma de México, Morelia, Michoacán, Mexico.
PLoS One. 2014 Feb 27;9(2):e89346. doi: 10.1371/journal.pone.0089346. eCollection 2014.
The repeated use of sleeping sites by frugivorous vertebrates promotes the deposition and aggregation of copious amounts of seeds in these sites. This spatially contagious pattern of seed deposition has key implications for seed dispersal, particularly because such patterns can persist through recruitment. Assessing the seed rain patterns in sleeping sites thus represents a fundamental step in understanding the spatial structure and regeneration of plant assemblages. We evaluated the seed rain produced by spider monkeys (Ateles geoffroyi) in latrines located beneath 60 sleeping trees in two continuous forest sites (CFS) and three forest fragments (FF) in the Lacandona rainforest, Mexico. We tested for differences among latrines, among sites, and between forest conditions in the abundance, diversity (α-, β- and, γ-components) and evenness of seed assemblages. We recorded 45,919 seeds ≥ 5 mm (in length) from 68 species. The abundance of seeds was 1.7 times higher in FF than in CFS, particularly because of the dominance of a few plant species. As a consequence, community evenness tended to be lower within FF. β-diversity of common and dominant species was two times greater among FF than between CFS. Although mean α-diversity per latrine did not differ among sites, the greater β-diversity among latrines in CFS increased γ-diversity in these sites, particularly when considering common and dominant species. Our results support the hypothesis that fruit scarcity in FF can 'force' spider monkeys to deplete the available fruit patches more intensively than in CFS. This feeding strategy can limit the effectiveness of spider monkeys as seed dispersers in FF, because (i) it can limit the number of seed dispersers visiting such fruit patches; (ii) it increases seed dispersal limitation; and (iii) it can contribute to the floristic homogenization (i.e., reduced β-diversity among latrines) in fragmented landscapes.
食果性脊椎动物对睡眠场所的反复利用，促进了大量种子在这些场所的沉积和聚集。这种种子沉积的空间传染模式对种子传播具有关键意义，特别是因为这种模式可以通过补充过程持续存在。因此，评估睡眠场所的种子雨模式是理解植物群落空间结构和更新的基本步骤。我们评估了墨西哥拉坎顿雨林中两个连续森林站点（CFS）和三个森林片段（FF）中60棵睡眠树下厕所中蜘蛛猴（Ateles geoffroyi）产生的种子雨。我们测试了不同厕所之间、不同站点之间以及森林条件之间种子组合在丰度、多样性（α-、β-和γ-成分）和均匀度方面的差异。我们记录了来自68个物种的45919颗长度≥5毫米的种子。FF中的种子丰度比CFS中的高1.7倍，这主要是由于少数植物物种占主导地位。因此，FF内的群落均匀度往往较低。FF之间常见和优势物种的β-多样性是CFS之间的两倍。尽管每个厕所的平均α-多样性在不同站点之间没有差异，但CFS中不同厕所之间更大的β-多样性增加了这些站点的γ-多样性，特别是在考虑常见和优势物种时。我们的结果支持以下假设：FF中的果实稀缺会“迫使”蜘蛛猴比在CFS中更密集地消耗可用的果实斑块。这种觅食策略可能会限制蜘蛛猴作为FF中种子传播者的有效性，因为（i）它可能会限制访问此类果实斑块的种子传播者数量；（ii）它会增加种子传播限制；（iii）它可能会导致破碎景观中的植物区系同质化（即不同厕所之间的β-多样性降低）。
