We present a new approach to determine the number and composition of guilds, using the hyperdiverse leaf-litter ant fauna as a model, based on appropriate morphological variables and species co-occurrence null models to describe the complex assemblages of interacting species community structure at the 1-m 2 scale. We obtained 18 linear morphometric measures from 949 workers of 171 leaf-litter ant species (18 762 measurements) surveyed in four Atlantic Forest localities to test whether the assemblages are morphologically structured; the morphological characters were selected to indicate diet and foraging habits. Principal components analysis was used to characterize the morphospace and to describe the guild structure (number of species and composition). The guild proportionality assembly rule (significant tendency toward constant proportion of species in guilds) was assessed at the 1-m 2 scale. Our analysis indicates that the division of leaf-litter ants into guilds is based mainly on microhabitat distribution in the leaf-litter, body size and shape, eye size, and phylogeny. The same guild scheme applied to four more sites shows that different Atlantic Forest areas have the same leaf-litter ant guilds. The guild proportionality assembly rule was confirmed for most guilds, suggesting that there are guild-specific limitations on species coexistence within assemblages; on the other hand, in a few cases the variance in guild proportion was greater than expected under the null assumptions. Other studies on ant functional group classification are partially supported by our quantitative morphological analysis. Our results, however, imply that there are more compartments than indicated in previous models, particularly among cryptic species (confined to soil and litter) and tropical climate specialists. We argue that a general null model for the analysis of species association based on morphology can reveal objectively defined groups and may thus contribute to a robust theory to explain community structure in general and have important consequences on studies of litter ant community ecology in particular.

1. In recent years the focus in ecology has shifted from species to a greater emphasis on functional traits. In tandem with this shift, a number of trait databases have been developed covering a range of taxa. Here, we introduce the GlobalAnts database.2. Globally, ants are dominant, diverse and provide a range of ecosystem functions. The database represents a significant tool for ecology in that it (i) contributes to a global archive of ant traits (morphology, ecology and life history) which complements existing ant databases and (ii) promotes a trait-based approach in ant and other insect ecology through a broad set of standardised traits.3. The GlobalAnts database is unique in that it represents the largest online database of functional traits with associated georeferenced assemblage-level data (abundance and/or occupancy) for any animal group with 9056 ant species and morphospecies records for entire local assemblages across 4416 sites. 4. We describe the structure of the database, types of traits included and present a summary of data coverage. The value of the database is demonstrated through an initial examination of trait distributions across subfamilies, continents and biomes.5. Striking biogeographic differences in ant traits are highlighted which raise intriguing questions as to the mechanisms generating them.

No abstract

No abstract

Leafcutter ants propagate co-evolving fungi for food. The nearly 50 species of leafcutter ants (Atta, Acromyrmex) range from Argentina to the United States, with the greatest species diversity in southern South America. We elucidate the biogeography of fungi cultivated by leafcutter ants using DNA sequence and microsatellite-marker analyses of 474 cultivars collected across the leafcutter range. Fungal cultivars belong to two clades (Clade-A and Clade-B). The dominant and widespread Clade-A cultivars form three genotype clusters, with their relative prevalence corresponding to southern South America, northern South America, Central and North America. Admixture between Clade-A populations supports genetic exchange within a single species, Leucocoprinus gongylophorus. Some leafcutter species that cut grass as fungicultural substrate are specialized to cultivate Clade-B fungi, whereas leafcutters preferring dicot plants appear specialized on Clade-A fungi. Cultivar sharing between sympatric leafcutter species occurs frequently such that cultivars of Atta are not distinct from those of Acromyrmex. Leafcutters specialized on Clade-B fungi occur only in South America. Diversity of Clade-A fungi is greatest in South America, but minimal in Central and North America. Maximum cultivar diversity in South America is predicted by the Kusnezov-Fowler hypothesis that leafcutter ants originated in subtropical South America and only dicot-specialized leafcutter ants migrated out of South America, but the cultivar diversity becomes also compatible with a recently proposed hypothesis of a Central American origin by postulating that leafcutter ants acquired novel cultivars many times from other nonleafcutter fungus-growing ants during their migrations from Central America across South America. We evaluate these biogeographic hypotheses in the light of estimated dates for the origins of leafcutter ants and their cultivars.

No abstract

Systematists have come under a barrage of criticism because of the alleged inadequacy of the 'traditional' taxonomic paradigm to curb the 'biodiversity crisis' and expeditiously make available the products of systematic research-usually species names-to the professional biological 'user' community (including ecologists, physiologists, population geneticists, and conservationists). The accusations leveled on systematists range from being 'slow' to 'incapable' of furnishing these products at a rate considered (by users) appropriate, especially given that the professional systematic community is portrayed as being in stark decline while operating in a quickly deteriorating natural world. Some of the critics have proposed solutions to this 'taxonomic impediment' in the form of a triumvirate adjoining a unitary taxonomic cyberstructure + automated DNA barcoding + molecular phylogeny, which we consider to be nothing but a threefold miopia; one critic has even gone as far as to suggest that biologists who need systematists can circumvent this dependency by 'doing systematics themselves'. The application of a quick-fix, 'automatedpragmatist' model is antithetical to a science endowed with a strong epistemological and theoretical foundation. We view the current propaganda in favor of automation and pragmatism in systematics as a distraction from the real issues confronting systematists, who must do more to impede the current trend that has 'marginalized' organismal biology in general. Simply increasing the rate of species descriptions, as suggested by critics, will not ameliorate the 'crisis'-taxa that correspond to incorrect hypotheses of biological entities (i.e. that are not monophyletic) will compromise the reliability of systematic information. Systematists must therefore provide more than 'binomials'-they must strive to produce vigorous hypotheses of comparative biology that are historical and theory-rich in order to augment the general reference system that is so critical to research in other biological sciences and conservation.

No abstract