Genetic variation in desiccation resistance and adaptability of the red imported fire ant (Hymenoptera : Formicidae) to arid regions
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abstract
We examined the genetic variation in resistance to desiccation in a polygyne fire ant, Solenopsis invicta Buren, population from central Texas using ful-sib analysis. Single-queen colonies were established artificially in the laboratory, and resulting daughters were subjected to desiccation upon maturity. We found significant genetic variation in time-to-death, and the heritability estimated using the Jackknife resampling method was significantly larger than zero (h2 = 0.4187). Head width was measured as an indicator of body size and heritability of body size was estimated. Body size and time-to-death was not genetically correlated, indicating that resistance to desciccation is not a function of body size. The significant genetic variaiton of desiccation resistance found in this study suggests that in a polygyne fire ant nest, queens with different degrees of resistance to desciccation may produce a cohort of workers that, as a group, can survive environments with a wide range of temporal and spatial variations in water availability.Results indicate that a polygyne fire ant population might be capable of adapting to arid habitats like those in western Texas, although at a slow pace as suggested by the low heritability. This study suggests that dominance of polygyne over monogyne fire ants in central and western Texas might be an adaptation to the local environments.
