Universidade Tecnológica Federal do Paraná, Santa Helena, PR, Brazil.
Universidade de São Paulo, Ribeirão Preto, PR, Brazil.
J Anim Ecol. 2021 Jun;90(6):1570-1582. doi: 10.1111/1365-2656.13477. Epub 2021 Apr 7.
Mechanisms promoting stable coexistence allow multiple species to persist in the same trophic level of a given network of species interactions. One of the most common stabilizing mechanisms of coexistence is niche differentiation, such as temporal and spatial patchiness. To understand the limits of coexistence between species we have to understand the limits of competitive interactions which translate in species exclusion or patterns of non-co-occurrence. We evaluated spatiotemporal niche-based mechanisms that could promote stable coexistence between ants and spiders which forage on extrafloral nectary (EFN)-bearing plants. We observed co-occurrence and overlapping patterns between ants and spiders in a temporal and spatial scale in nine different EFN-bearing plant species in a Neotropical savanna, using both community and species-level approach. Ants and spiders showed asynchrony of their abundances over the year with low temporal overlapping patterns between them (temporal niche specialization). Greater abundance of ants occurred between September and March, whereas greater abundance of spiders occurred between March and August, exactly at the time when the abundance of ants decreases on plants. However, there might also be some levels of temporal overlapping, but then individual ants and spiders occupy different branches (spatial segregation). Finally, we also observed a spatial negative effect of the abundance of ants on the presence of spiders. Our results suggest that spatiotemporal partitioning between ants and spiders may be one of the potential mechanisms behind a stable coexistence between these two groups of organisms that forage on EFN-bearing plants in the Brazilian savanna.
促进稳定共存的机制允许多个物种在给定的物种相互作用网络中同一营养级上持续存在。共存的最常见稳定机制之一是生态位分化，例如时间和空间的斑块性。为了了解物种之间共存的极限，我们必须了解竞争相互作用的极限，这些相互作用导致物种排斥或非共存模式。我们评估了基于时空生态位的机制，这些机制可以促进在觅食于额外花蜜（EFN）植物的蚂蚁和蜘蛛之间的稳定共存。我们在热带稀树草原的九种不同的 EFN 植物物种中，在时间和空间尺度上观察到了蚂蚁和蜘蛛的共存和重叠模式，同时采用了群落和物种水平的方法。蚂蚁和蜘蛛的丰度在一年中表现出不同步，它们之间的时间重叠模式较低（时间生态位特化）。蚂蚁的丰度在 9 月至 3 月之间较高，而蜘蛛的丰度在 3 月至 8 月之间较高，正好是蚂蚁在植物上的丰度下降的时候。然而，可能也存在一些时间重叠，但个体蚂蚁和蜘蛛占据不同的分支（空间隔离）。最后，我们还观察到蚂蚁丰度对蜘蛛存在的空间负效应。我们的结果表明，蚂蚁和蜘蛛之间的时空分离可能是这些在巴西稀树草原中觅食于 EFN 植物的两种生物之间稳定共存的潜在机制之一。
