Overview of the Distribution, Habitat Association and Impact of Exotic Ants on Native Ant Communities in New Caledonia

• Published in: PloS one Vol. 8; no. 6; p. e67245
• Main Authors: Berman, Maïa, Andersen, Alan N, Hély, Christelle, Gaucherel, Cédric
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 26-06-2013; Public Library of Science (PLoS)
• Subjects: Abundance; Animal behavior; Animals; Anoplolepis gracilipes; Ants; Baiting; Biodiversity; Biodiversity and Ecology; Biology; Community composition; Ecosystem; Ecosystem biology; Ecosystems; Environmental Sciences; Fauna; Formicidae; Functional groups; Habitats; Hymenoptera; Industrial research; Introduced Species; Islands; Multivariate analysis; New Caledonia; Nonnative species; Pheidole megacephala; Population Dynamics; Rainforests; Savannahs; Species composition; Volcanoes; Wasmannia auropunctata; New Caledonia; fire ant; functional-groups; Argentine ant; species richness; invasion; introduced ant
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0067245

Ants are among the most ubiquitous and harmful invaders worldwide, but there are few regional studies of their relationships with habitat and native ant communities. New Caledonia has a unique and diverse ant fauna that is threatened by exotic ants, but broad-scale patterns of exotic and native ant community composition in relation to habitat remain poorly documented. We conducted a systematic baiting survey of 56 sites representing the main New Caledonian habitat types: rainforest on ultramafic soils (15 sites), rainforest on volcano-sedimentary soils (13), maquis shrubland (15), Melaleuca-dominated savannas (11) and Acacia spirorbis thickets (2). We collected a total of 49 species, 13 of which were exotic. Only five sites were free of exotic species, and these were all rainforest. The five most abundant exotic species differed in their habitat association, with Pheidole megacephala associated with rainforests, Brachymyrmex cf. obscurior with savanna, and Wasmannia auropunctata and Nylanderia vaga present in most habitats. Anoplolepis gracilipes occurred primarily in maquis-shrubland, which contrasts with its rainforest affinity elsewhere. Multivariate analysis of overall ant species composition showed strong differentiation of sites according to the distribution of exotic species, and these patterns were maintained at the genus and functional group levels. Native ant composition differed at invaded versus uninvaded rainforest sites, in the absence of differences in habitat variables. Generalised Myrmicinae and Forest Opportunists were particularly affected by invasion. There was a strong negative relationship between the abundance of W. auropunctata and native ant abundance and richness. This emphasizes that, in addition to dominating many ant communities numerically, some exotic species, and in particular W. auropunctata, have a marked impact on native ant communities.