Can environmental complexity predict functional trait composition of ground-dwelling ant assemblages? A test across the Amazon Basin

• Published in: Acta oecologica (Montrouge) Vol. 99; p. 103434
• Main Authors: Guilherme, Diego Rodrigues, Souza, Jorge Luiz Pereira, Franklin, Elizabeth, Pequeno, Pedro Aurélio Costa Lima, Chagas, Andreia Conceição das, Baccaro, Fabricio Beggiato
• Format: Journal Article
• Language: English
• Published: Elsevier Masson SAS 01-08-2019
• Subjects: Amazon basin; Environmental complexity; Formicidae; Functional traits; Pitfall traps; Tropical forest; Environmental complexity; Formicidae; Functional traits; Tropical forest; Amazon basin; Pitfall traps
• ISSN: 1146-609X; 1873-6238
• DOI: 10.1016/j.actao.2019.05.004

Environmental gradients may influence species distributions by filtering their functional traits, resulting in a correspondence between community functional composition and local environmental conditions. We used a vegetation gradient as an indicator for environmental complexity to test whether it predicted the morphological composition of ground-dwelling ant assemblages across geographic extents. The sampling design covered 126 plots distributed across eight sampling sites along a broad environmental gradient in the Amazon Basin. Plots covered different phytophysiognomies that have a strong relation with forest biomass and, consequently, litter production. We selected six morphological traits related to ant foraging strategies and behavior. Generalized linear mixed models were used to predict how environmental complexity affects trait composition of ground-dwelling ant assemblages. Structurally less complex environments (eg. Amazonian savannah) harboured more species of smaller ants, with relatively smaller mandibles and relatively larger eyes. In more complex environments (eg. dense ombrophylous forest), there were more ant species of larger size, with relatively larger mandibles and relatively smaller eyes. No relationship was detected between relative femur length and the environmental gradient investigated. The functional approach focused on individual traits may illuminate which ant foraging strategies are best adapted to a particular habitat. Our data reveal that the morphological composition of ground-dewelling ant assemblages responds clearly to environmental complexity suggesting that certain ant characteristics offer ecological advantages to particular species in particular habitats.
[Display omitted]
•We tested whether the environmental complexity in a vegetation gradient can predict the morphological composition of ground-dwelling ant assemblages. Increasing environmental complexity increased body size, relative mandible length, and decreased eye size of ant species. Our data reveal a clear response pattern of morphological composition of ground-dwelling ant assemblages to the environmental gradient. The environmental complexity can act favouring species with certain characteristics associated with certain habitats.