Field experiments on desert ants: testing for competition between colonies

• Published in: Ecology (Durham) 1988-12, Vol.69 (6), p.1993-2003
• Main Authors: Ryti, Randall T., Case, Ted J.
• Format: Article
• Language: English
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Animals; Ants; Autoecology; Biological and medical sciences; BUSQUEDA DE ALIMENTO; COLONIALISM; COLONIALISME; COLONIALISMO; Demecology; Desert insects; Deserts; DIET; DIETA; Ecological competition; ESSAI; Food; FORAGING; Formicidae; Fundamental and applied biological sciences. Psychology; Insect colonies; Insect ecology; PERFORMANCE DE REPRODUCTION; POGONOMYRMEX; Pogonomyrmex californicus; Protozoa. Invertebrata; PRUEBAS; RECHERCHE DE NOURRITURE; REGIME ALIMENTAIRE; REPRODUCTIVIDAD; REPRODUCTIVITY; TRIALS; VEROMESSOR PERGANDEI; Worker insects
• ISSN: 0012-9658; 1939-9170
• DOI: 10.2307/1941177

Our previous observations and short-term experiments on two granivorous ant species in the California desert indicated that established colonies may compete intraspecifically. Here we report the results of 3-yr neighbor-removal and food-addition experiments that tested for the presence of intraspecific and interspecific competition between colonies. We followed the responses of territory use, diet breadth, foraging activity, and reproductive output (alate production) to the treatments. Both territory use and alate production patterns were consistent with the predictions of intraspecific resource competition. We found to evidence for interspecific effects between colonies. Specifically, Veromessor pergandi @'neighbor-removed@' colonies foraged randomly throughout the treatments, while control colonies tended to forage away from their nearest conspecific neighbor when resource levels were low. Both food-supplemented and neighbor-removed V. pergandei colonies produced proportionately more alates than control colonies. There were no treatment effects on diet breadth or foraging activity at V. pergandei or Pogonomyrmex californicus colonies. Since other experiments on desert granivores have shown significant competitive effects on colony density over the same time scale, the lack of consistent effects of competition was most likely due to: (1) differences between the communities in relation to seed storage and productivity and (2) the fact that our experiments only tested for competition between established colonies and did not consider potential competitive effects of established colonies on alate survival (colony regeneration).