Are the spatio-temporal dynamics of soil-feeding termite colonies shaped by intra-specific competition?

Authors

  • THOMAS BOURGUIGNON,

    1. Evolutionary Biology and Ecology, Department of Organism Biology, Université Libre de Bruxelles, Brussels, Belgium
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    • Current address: Division of Biosphere Science, Graduate School of Environmental Science, Hokkaido University, Sapporo 060-0810, Japan.

  • MAURICE LEPONCE,

    1. Section of Biological Evaluation, Department of Education and Nature, Royal Belgian Institute of Natural Sciences, Brussels, Belgium
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  • YVES ROISIN

    Corresponding author
    1. Evolutionary Biology and Ecology, Department of Organism Biology, Université Libre de Bruxelles, Brussels, Belgium
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Yves Roisin, Evolutionary Biology and Ecology, CP 160/12, Department of Organism Biology, Université Libre de Bruxelles, Avenue F.D. Roosevelt 50, 1050 Brussels, Belgium. E-mail: yroisin@ulb.ac.be

Abstract

1. Soil-feeding termites are abundant and diversified in neotropical forests, where they are among the major decomposers of the soil macrofauna. While niche specialisation along the humification gradient may reduce inter-specific competition, some species are represented by numerous colonies likely to be involved in intra-specific competition, but the subterranean nesting habits of most species of soil-feeding termites make direct observations difficult.

2. The soldierless species Anoplotermes banksi Emerson was studied, which, unlike other Anoplotermes-group species, builds arboreal nests that can be easily detected. To infer the biological processes driving the spatial distribution of this species, we conducted a 3-year survey of the dynamics of colonisation of a 1-ha plot by A. banksi. Ripley's L-function, detecting aggregation or dispersion at various spatial scales, was used to investigate the distribution pattern of A. banksi nests, as well as the distribution of new and established nests.

3. Only one-fourth of the nests recorded the first year were still alive after 3 years, highlighting a rapid turnover of the A. banksi nest population. Age classes were differentially affected by mortality, which was higher in young nests than in large, established nests.

4. Established nests were overdispersed at a short range, whereas young nests had a random or clumped distribution. Young nests tended to be overdispersed from established ones and were more abundant in areas with recently dead nests. Dead nests predominantly occurred where A. banksi nests were particularly abundant. Altogether, the present results indicate a negative interaction between neighbouring colonies suggesting intra-specific competition.

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