Spatiotemporal niche‐based mechanisms support a stable coexistence of ants and spiders in an extrafloral nectary‐bearing plant community

Abstract

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.

Dear neighbor: Trees with extrafloral nectaries facilitate defense and growth of adjacent undefended trees

“…In some situations, nonant natural enemies can be the numerous visitors of EFN plants, which could in our setting also benefit neighbor trees. These natural enemies may attenuate the observed influence of EFN trees, for example, when spatiotemporal complementarity among enemy groups exists (Lange et al, 2021), but we could not reliably sample these mostly winged species with the applied beating method. In turn, ants could also reduce the abundance of other natural enemies.…”

Spatio‐temporal species aggregations do not rule out interspecific competition in tree hollow spider assemblages

“…Spatial aggregations generally occur between species that share an ecological niche, as demonstrated by numerous studies (Azeria et al, 2012; Azeria, Fortin, Hébert, et al, 2009; Holt, 1984; Peres‐Neto, 2004; Sánchez‐Galván et al, 2018). However, studies of co‐occurrence patterns often do not include the temporal dimension (Lange et al, 2021), even when ‘true’ aggregation (i.e., where an interaction between the two species is highly likely) occurs spatially and temporally. In fact, by studying species phenology together with the spatial aggregations that resulted from statistical analyses, only 20% of the non‐random aggregation patterns, formed by species pairs A. scopolii – S. scutulatus and E. atrica – L. majus , occurred at the spatio‐temporal level.…”

“…In contrast, non‐random segregation patterns are attributed to competition phenomena (Camarota et al, 2016; Gotelli & Graves, 1996) or habitat filtering (Azeria et al, 2012; Oliveira‐Junior et al, 2021). In addition, co‐occurrence patterns can be studied at both the matrix (the whole community) and pairwise (species pairs) levels, although combining them is recommended because they provide different information (Lange et al, 2021; Oliveira‐Junior et al, 2021; Sánchez‐Galván et al, 2018).…”

Foliar herbivory increases sucrose concentration in bracteal extrafloral nectar of cotton

“…Total sugar content, which can include sucrose, is reported to be a determining factor in changes to ant foraging preferences to different EF nectars [47,48]. Typically, damage induces greater amounts of EF nectar produced, making more sugars available to foraging ants even if the concentration of sugars remains the same (e.g., [3,11,12,26,49].…”

“…Many plant species also recruit natural enemies by providing an attractive food source in the form of extrafloral (EF) nectar. EF nectar, which is typically rich in sucrose, glucose, and fructose, encourages ants, parasitoids, and other predatory arthropods such as spiders [3,4] to forage for carbohydrates on the plant (reviewed in [5]). This improves the chance of an encounter between the natural enemies and herbivores such as caterpillars that may be damaging the plant.…”