Dinner with the roommates: trophic niche differentiation and competition in a mutualistic ant‐ant association

Abstract

1. The potential for competition is highest among species in close association. Despite net benefits for both parties, mutualisms can involve costs, including food competition. This might be true for the two neotropical ants Camponotus femoratus and Crematogaster levior, which share the same nest in a presumably mutualistic association (parabiosis). 2. While each nest involves one Crematogaster and one Camponotus partner, both taxa were recently found to comprise two cryptic species that show no partner preferences and seem ecologically similar. Since these cryptic species often occur in close sympatry, they might need to partition their niches to avoid competitive exclusion. 3. Here, we investigated first, is there interference competition between parabiotic Camponotus and Crematogaster, and do they prefer different food sources under competition? And second, is there trophic niche partitioning between the cryptic species of either genus? 4. Using cafeteria experiments, neutral lipid fatty acid and stable isotope analyses, we found evidence for interference competition, but also trophic niche partitioning between Camponotus and Crematogaster. Both preferred protein‐ and carbohydrate‐rich baits, but at protein‐rich baits Ca. femoratus displaced Cr. levior over time, suggesting a potential discovery‐dominance trade‐off between parabiotic partners. Only limited evidence was found for trophic differentiation between the cryptic species of each genus. 5. Although we cannot exclude differentiation in other niche dimensions, we argue that neutral dynamics might mediate the coexistence of cryptic species. This model system is highly suitable for further studies of the maintenance of species diversity and the role of mutualisms in promoting species coexistence.

Stable isotopes disentangle niche partitioning and species co-occurrence in a multi-level marine mutualism

“…In most cases, studies that employ stable isotopes to disentangle insect demonstrate, like ours, that co-occurring symbionts exhibit clear isotopic niche partitioning (e.g. Tillberg 2004, Parmentier et al 2016, Trimble and Sagers 2004, Sprenger et al 2021). However, microhabitat partitioning by symbionts is not always indicative of trophic or isotopic niche differentiation.…”

Co-habiting ants and silverfish display a converging feeding ecology

“…This tight relationship implies that these silverfish not only feed on similar food sources but also flexibly adapt their diet in accordance with the foraging decisions of the host colony. Previously, coupling of the isotopic niche among co-habiting animals have been shown in host-parasite systems [ 48 ], co-habiting ant species [ 49 ], co-habiting termite species [ 50 ], and myrmecophiles and their ant host [ 51 ]. In these studies, although the δ 13 C-δ 15 N (or only δ 15 N) profiles of the co-habiting species covary, there was a clear difference in the isotopic composition of the co-habiting species.…”

Co-habiting ants and silverfish display a converging feeding ecology

“…This tight relationship implies that these silverfish not only feed on similar food sources but also flexibly adapt their diet in accordance with the foraging decisions of the host colony. Previously, coupling of the isotopic niche among co-habiting animals have been shown in host-parasite systems (Gómez-Díaz & González-Solís, 2010), co-habiting ant species (Sprenger et al, 2021), co-habiting termite species (Florencio et al, 2013) and myrmecophiles and their ant host (Parmentier et al, 2023). In these studies, although the δ 13 C-δ 15 N (or only δ 15 N) profiles of the co-habiting species covary, there was a clear difference in the isotopic composition of the co-habiting species.…”