Competition for foraging resources and coexistence of two syntopic species of Messor harvester ants in Mediterranean grassland |
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Authors: | LUIGI SOLIDA ALESSANDRA CELANT LUCA LUISELLI DONATO A GRASSO ALESSANDRA MORI ALBERTO FANFANI |
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Institution: | 1. Dipartimento di Biologia e Biotecnologie ‘Charles Darwin’, Università di Roma ‘Sapienza’, Roma, Italy;2. Dipartimento di Biologia Ambientale, Università di Roma ‘Sapienza’, Roma, Italy;3. Centro Studi Demetra s.r.l., Dipartimento Ambiente Eni Spa, Roma, Italy;4. Dipartimento Biologia Evolutiva e Funzionale, Università di Parma, Parma, Italy |
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Abstract: | 1. Diet composition of two syntopic species of Messor seed‐harvester ants (M. wasmanni Krausse and M. minor André) was evaluated during different periods over the year (May, July, October), by analysing food type (plant parts and species) and food size (weight, length, width). Morphological traits of foragers (head width and femur length) considered important features promoting diet partitioning were measured. 2. We used two robust randomisation algorithms (RA2 and RA3), adopted in niche overlap studies, to check for random vs non random utilisation of resources at intra‐ and interspecific level for the different periods. 3. Analyses showed high levels of overlap in the diet of the two species and no evidence of interspecific competition during most of the activity season. In particular, there was an aggregated use of resources in summer, whilst niche partitioning and evidence of competition when resources decreased in autumn. Intraspecifically, no evidence of competition was found. 4. Results suggest two different mechanisms for minimising competition: when food resources are abundant (summer), ants collected the same plant species but selected different sizes; when food resource is scarce (autumn), ants foraged on different plants. 5. The importance of different factors (morphological, behavioural, ecological) possibly affecting competition and coexistence are discussed. |
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Keywords: | Coexistence diet Messor ants morphology niche overlap null models |
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