Trophic ecology of the arboreal and ground ant communities in forests and savannas of central Brazil

Abstract

1. The trophic ecology of organisms is often mediated by habitat characteristics. Ants are key organisms of most food webs, and their diet can be plastic depending on the relative availability of different nutrients.2. Using stable isotope analysis, we investigated whether there were differences in the trophic position (δ 15 N) and/or in the relative importance of different carbon sources (δ 13 C) between the arboreal and ground-dwelling ant communities inhabiting two adjacent and contrasting habitats (savannas and semideciduous forests).3. Arboreal species on average occupied lower trophic positions (lower δ 15 N) than did the ground-dwelling species, as probably in the arboreal stratum there is a prevalence of genera whose species rely heavily on plant and insect exudates. However, regardless of the foraging/nesting strata, there was no difference in mean δ 15 N between the savanna and forest communities, indicating that differences between these two habitats in the relative availability of sources of protein and carbohydrates for ants are either small or non-significant.4. The savanna ant community presented a greater δ 13 C than did the forest community, as expected, given the high abundance of C 4 grasses in savannas. However, the difference in δ 13 C between the two communities was relatively small, as few savanna species derived most of their carbon from C 4 -based food webs.5. Overall, our study provided important insights into the trophic ecology of ant communities inhabiting contrasting natural habitats, such as different vegetation strata and adjacent forests and savannas.

Historical biogeography shapes functional ecology: Inter‐continental contrasts in responses of savanna ant communities to stress and disturbance

“…Generic composition of the cerrado ant fauna is very similar to that of rainforest (Vieira et al, 2021), which is in striking contrast to the case in Australia where rainforest and savanna faunas are highly disjunct at the genus level (van Ingen et al 2008). Moreover, many ants in cerrado are widespread forest species, and these extend not just into cerrado but also into semi-arid Caatinga (Leal et al, 2018).…”

“…For example, phylogenetic analyses of two prominent groups of cerrado ants, the turtle ants of the genus Cephalotes (Price et al, 2014) and the fungus‐growing ants (including the leaf‐cutter genus Atta ; Branstetter et al, 2017), indicate that both originated in rainforest and more recently diversified in dry habitats. Generic composition of the cerrado ant fauna is very similar to that of rainforest (Vieira et al, 2021), which is in striking contrast to the case in Australia where rainforest and savanna faunas are highly disjunct at the genus level (van Ingen et al 2008). Moreover, many ants in cerrado are widespread forest species, and these extend not just into cerrado but also into semi‐arid Caatinga (Leal et al, 2018).…”

Macroecological patterns of functional and phylogenetic diversity vary between ground and arboreal assemblages in Neotropical savanna ants

“…Similarly, there is little information on the extent to which ant communities associated with different vertical strata respond differentially to macroscale climatic gradients, or on potential differences in the relative importance of competition versus environmental filtering as mechanisms structuring ground and arboreal communities. Arboreal and ground‐dwelling ant communities occupy distinct habitats, which differ from each other in many aspects, such as in microclimate (Scheffers et al 2013, Leahy et al 2022), food resources (Yanoviak and Kaspari 2000, Blüthgen et al 2003, Vieira et al 2021), and nesting substrates (Almeida et al 2023). Furthermore, arboreal and ground‐dwelling ants show differences in their thermal tolerances (Leahy et al 2022) and in the extent to which they can adapt to climatic variation through flexible foraging along the vertical gradient (Leahy et al 2022, Vasconcelos et al 2023).…”

Vertical stratification of ant assemblages varies along a latitudinal gradient in Brazilian savanna

“…This is considered a derived nesting habit, given that the representatives of the older ant lineages all nest on the ground or in the litter layer (Blaimer et al, 2015; Brühl et al, 1998). Arboreal and ground‐dwelling ants from Brazilian savanna tend to have different nutritional requirements and to occupy different trophic positions, with many of the former specializing on liquid carbohydrate in the form of honeydew or extra‐floral nectar (Vieira et al, 2021).…”