PARENT SESSION
Oral Session #46: Disturbance Ecology.
Presiding: M. Slocum
Tuesday, August 6. 1:00 PM to 4:45 PM. Grand Ballroom East, Radisson.

Genetic divergence and soil-related phenotypic plasticity following fire in the Mojave Desert.

Vanier, Cheryl^*,1,2, Thompson, Daniel², ¹ Department of Ecology and Evolutionary Biology, Tucson, AZ² Department of Biological Sciences, Las Vegas, NV

ABSTRACT- Plant population responses to a burned environment can result from the integration of many separate factors, including changes in perennial vegetation cover, light, temperature, moisture, soil quality, and past response to selection in a burned site. In this study, we focused on phenotypic differences in the field that could be attributed to soil quality and site of origin. We measured phenotypes in the field and in the greenhouse for the native Mojave Desert annual, Amsinckia tessellata, for two field seasons, one with high rainfall and one with average rainfall. Characters relating to rosette morphology, phenology, adult morphology, and allocation were studied. Strong temporal heterogeneity was observed both in the field and in the greenhouse, although few genetic effects or interactions between time and soil occurred. Few characters differed by site of seed origin. Soil effects were observed for seedling characters, most phenology variables, two adult characters, and stem allocation. Differences in morphology found early in life did not last to the adult stage, suggesting that soils alter the growth trajectories of these plants, but the absolute size is relatively constant within a year. Phenotypic differences in the greenhouse could be attributed to genetic divergence or maternal effects.

KEY WORDS: fire, desert, annual plant, genetic divergence