Ant community structure on a small Pacific island

Authors: Xim Cerdá Elena Angulo Stéphane Caut Franck Courchamp

Publish Date: 2011/07/30

Volume: 14, Issue: 2, Pages: 323-339

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Abstract

In most studies about ant communities species are grouped into competitive hierarchies where top dominants drive the majority of other species away from resources Nevertheless in some ecosystems high ground temperatures may disrupt this hierarchical organization Other changes in community structure are caused by the arrival of invasive ant species which rapidly disassemble local communities We studied the effects of competition and temperature on ant community organization on Surprise Island New Caledonia Four different habitats were distinguished a central plain a sea shore Argusia shrubland a dense Scaveola shrub and an arboreal Pisonia strata Eight ant species were identified from pitfall traps seven introduced and only one native species Pheidole oceanica Ant assemblages in each habitat had a different ecologically dominant species and a dominant species in one habitat could be nondominant and less abundant in another From interactions at baits we built a competitive hierarchy where the top dominant species was the native Ph oceanica Daily foraging activity rhythms of the different species mostly overlapped The relationship between bait occupation and ground temperature followed a negative linear pattern at all sites and for most species except for the relatively thermophilous Monomorium floricola Indices of cooccurrence in pitfall traps indicated that species cooccurred randomly with respect to one another Conversely species appeared to be segregated when we examined cooccurrence at baits at the sites where Ph oceanica was abundant Oceanic islands are very susceptible to alien species but on Surprise Island it seems that the sole native species dominates in some habitats when confronted by invasive speciesWe would like to thank the French Navy in New Caledonia especially the commander and crew of “La Moqueuse” for transport onto the island Isabelle Brun for logistic assistance at the “Grande Terre” Francisco Carro Paco JeanLouis Chapuis Vincent Hulin and Mathias Gerhardt helped in the daily routine on the island and Paco also in the ant field work We are very grateful to Hervé Jourdan IRD Nouméa and Jacques H Delabie CEPECCEPLAC Itabuna for ant identification Funds were provided by the French Agence Nationale de la Recherche to FC Thanks are due for very helpful comments to Nate Sanders to two anonymous referees to Stephen Gregory and Donna Harris during ESE coffee meetings and to EBD Ant Group members Raphaël Boulay Ana Carvajal Michael Jowers Jessica PearceDuvet Camille Ruel and Louise van Oudenhove during lab meeting Thanks to Nick Gotelli for help with EcoSim to Neus MariMena for pitfall trap analysis of the first survey in 2003 and to Javi Retana and Dan Simberloff for accurate and constructive comments on a previous draft and during Caut’s PhD thesis dissertation respectively Jacqueline Minett Wilkinson and Michael J Jowers revised the English A first version was drafted during a XC sabbatical stay in France supported by the Spanish Ministry of Education and Science Sabbatical PR20040539 PR20060412 All experiments comply with current Spanish and French laws

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