Diurnal foraging ant–tree co‐occurrence networks are similar between canopy and understorey in a Neotropical rain forest

Abstract

Discussion of the vertical stratification of organisms in tropical forests has traditionally focused on species distribution. Most studies have shown that, due to differences in abiotic conditions and resource distribution, species can be distributed along the vertical gradient according to their ecophysiological needs. However, the network structure between distinct vertical strata remains little‐explored. To fill this gap in knowledge, we used baits to sample ants in the canopy and understorey trees of a Mexican tropical rain forest to record the ant–tree co‐occurrences. We examined the ant–tree co‐occurrences in the canopy and understorey using complementary network metrics (i.e., specialization, interaction diversity, modularity, and nestedness). In addition, we evaluated co‐occurrence patterns between ant species on trees, using C‐score analysis. In general, we found no differences in the network structure, although the interaction diversity was greater in the understorey than in the canopy networks. We also observed that co‐occurrence networks of each vertical stratum featured four ant species in the central core of highly co‐occurring species, with three species unique to each stratum. Moreover, we found a similar trend toward ant species segregation in the both strata. These findings reveal a similar pattern of ant–ant co‐occurrences in both vertical strata, probably due to the presence of arboreal‐nesting ants in the understorey. Overall, we showed that despite the marked differences in species composition and environmental conditions between understorey and canopy strata, ant–tree co‐occurrences in these habitats could be governed by similar mechanisms, related to dominance and resource monopolization by ants.Abstract in Spanish is available with online material.

Environmental drivers of ant dominance in a tropical rainforest canopy at different spatial scales

“…(2020) showed that the abundance of ants in the upper and lower canopies depends on season in an Australian tropical rainforest, with higher levels of activity in the upper canopy only during the dry season. Therefore, higher levels of ant foraging activity found at lower heights within the canopy is likely because arboreal and epigeic ants often move between the ground and the canopy top, crossing through the intermediate layers (Hahn & Wheeler, 2002; Hashimoto et al ., 2010; Dejean et al ., 2019; Macedo‐Reis et al ., 2019; Antoniazzi et al ., 2020). Here, we found that the probability of ant presence on baits decreased with the distance from the ground.…”

“…Here, we found that the probability of ant presence on baits decreased with the distance from the ground. The most frequent species present on our baits, C. sericeiventris and P. dossena , often nest in the understory and can be found in the canopy, the understory, and at ground level (Fisher, 2002; Yamamoto & Del‐claro, 2008; Antoniazzi et al ., 2020). A previous study performed in our study area showed that, in general, ant species composition differs between canopy and understory (Antoniazzi et al ., 2020).…”

“…The most frequent species present on our baits, C. sericeiventris and P. dossena , often nest in the understory and can be found in the canopy, the understory, and at ground level (Fisher, 2002; Yamamoto & Del‐claro, 2008; Antoniazzi et al ., 2020). A previous study performed in our study area showed that, in general, ant species composition differs between canopy and understory (Antoniazzi et al ., 2020). In addition, and contrary to our hypothesis, we found no evidence that micro‐environmental characteristics (i.e., distance to the trunk, distance to the crown surface, distance to the upper surface of the tree crown, the thickness of the branch, or the percentage of branch coverage by epiphyte/climbing plants) are related to the probability of ant presence on baits.…”

“…Woody climbing plants, lianas, occur in a high proportion of the trees in this forest (Pérez‐Salicrup & Meijere, 2005). Few studies have reported on canopy ants in the study area, but the species of at least eight genera are known to dwell in the canopy: Azteca , Camponotus , Dolichoderus , Myrmelachista , Pachycondyla , Pheidole , Pseudomyrmex , and Tetramorium (Estrada & Coates‐Estrada, 1986; Ibarra‐Manríquez & Dirzo, 1990; Alvarez‐Buylla & Martínez‐Ramos, 1992; Martínez‐Mota et al ., 2004; Antoniazzi et al ., 2020).…”

“…The ants that fell onto this piece of fabric were also collected. Then, all the ants were sorted, mounted, and identified to the lowest possible taxonomic level using the reference collection from the Los Tuxtlas study site (Antoniazzi et al ., 2020) and according to the MEXICO ANTS database (Dáttilo et al ., 2020) with the support of specialists from the entomological collection (IEXA) of Instituto de Ecología A.C. (INECOL), Xalapa, Mexico.…”