Deciphering the mechanisms that underpin dietary specialization and niche partitioning is crucial to understanding the maintenance of biodiversity. New world army ants live in species‐rich assemblages throughout the Neotropics and are voracious predators of other arthropods. They are therefore an important and potentially informative group for addressing how diverse predator assemblages partition available prey resources. New World army ants are largely specialist predators of other ants, with each species specializing on different ant genera. However, the mechanisms of prey choice are unknown. In this study, we addressed whether the army ant Using field experiments, we tested the response of army ants to the following four odour treatments: alarm odours, dead ants, live ants and nest material. Each treatment had a unique combination of odour sources and included some movement in two of the treatments (alarm and live ants). Odour treatments were tested for both prey and non‐prey ants. These data were used to determine the degree to which Army ants responded strongly to odours derived from prey ants, which triggered both increased localized recruitment and slowed advancement of the raid as they targeted the odour source. Odours from non‐prey ants were largely ignored. Additionally, the army ants had the strongest response to the nest material of their preferred prey, with progressively weaker responses across the live ant, dead ant and alarm odours treatments respectively. This study reveals that the detection of prey odours, and especially the most persistent odours related to the prey's nest, provides a mechanism for dietary specialization in army ants. If ubiquitous across the Neotropical army ants, then this olfaction‐based ecological specialization may facilitate patterns of resource partitioning and coexistence in these diverse predator communities.
Myrmecophagy is one of the most common dietary specializations among vertebrates. Ants are an important food resource for many lizard species. Here, we use a large dataset on ant consumption by lizards (345 species, 33 families) to explore evolutionary and ecological correlates of myrmecophagy across the evolutionary history of lizards. Based on literature and previous empirical work, we develop and test the following hypotheses about myrmecophagy: (i) it does not occur randomly across Squamata; it is correlated with (ii) foraging mode, (iii) habitat, (iv) body size, (v) aridity, and/or (vi) species range size. We found that ant ingestion is not distributed randomly in the phylogeny, with higher ingestion concentrated in some Iguania. Myrmecophagy also evolved in Lacertoidea and it is a derived trait with relatively recent origin. Foraging mode, habitat, body size, and aridity do not influence ant ingestion. Species with smaller range sizes show high variability in ant ingestion, whereas lizards with larger ranges tend to eat a lower proportion of ants. This result confirms the general ecological pattern that specialization is more common in narrowly distributed species. We suggest that future studies should also explore dietary specialization more broadly and provide a better taxonomic resolution of ant species in the diet of lizards.
more » « less- NSF-PAR ID:
- 10477354
- Publisher / Repository:
- Oxford University Press
- Date Published:
- Journal Name:
- Zoological Journal of the Linnean Society
- ISSN:
- 0024-4082
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Location Veracruz, Mexico.
Taxon Leaf‐litter ants.
Methods We sampled 320 m2of leaf litter spread across eight equally spaced sites from sea level to 3500 m of elevation. We used regression models to predict α‐diversity patterns with climatic (temperature and precipitation) and spatial (geometric constraints) variables. We also assessed, through multiple regression based on distance matrices (MRM), the relative importance of habitat filtering and dispersal limitations for shaping total dissimilarity (βsor), turnover (βsim) and nestedness (βnes).
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