Body Size and Division of Labor Based on Body Size
The seed-harvesting ant Vermomesser pergandei is a harvesting ant common in the deserts of southern California, Arizona, Baja California, and Sonoran Mexico (Creighton 1953). It displays a high degree of worker size variation, having a body length size range from 3.5mm to 8.4mm. The variation in size is described as monophasic allometry (allometric relationships with single slope, Rissing 1987).
Published morphological data on this species has used head width (Rissing and Pollock 1984) and mandible length (Davidson 1978). The motivation for using these measures stems from their ecology as seed-harvesting ants, inferring head width and mandible length play an important role in determining seed size harvested.Measurement Size range Citation Head Width 0.8-1.88mm Rissing and Pollock 1984, Rising 1987 Mandible Length 0.5-1.05mm Davidson 1978
Evidence suggests variability of mandible size (correlated to body size) decreases as competition increases (Davdison 1978). However in this species seed size and worker body size is not 'size-matched', in that larger workers do not necessarily carry the largest seeds as foraging theory predicts (Rissing and Pollock 1984).
- Davidson, DW. 1978. Size variability in the worker caste of a social insect (Veromessor pergandei Mayer) as a function of the competitive environment. Am Nat. 112:523-532.
- Rissing, SW and Pollock, GB. 1984. Worker size variability and foraging efficiency in Veromessor pergandei (Hymenoptera: Formicidae). Behav Ecol Sociobiol. 15:121-126.
- Rissing, SW. 1987. Annual cycles in worker size of the seed-harvester ant Veromessor pergandei (Hymenoptera: Formicidae). Behav. Ecol. Sociobiol. 20: 117-124.