Wednesday, August 8, 2007 - 2:50 PMCOS 89-5: Cost of reproduction in a short-lived perennial plant: Live hard, die young
Cristina F. Aragón, Marcos Méndez, and Adrián Escudero. Universidad Rey Juan Carlos
Life-history theory assumes that organisms have limited resources to invest in different functions, and thus reproductive investments would involve costs in terms or growth, future fecundity and/or future survival. However, our knowledge of quantitative relationships between resource investments in reproduction and their associated costs is still scant. The goal of this work was to estimate reproductive costs on a short-lived perennial plant, Helianthemum squamatum, an Iberian semiarid specialist restricted to gypsum soils. The study was conducted in two nearby sites of contrasting slope aspect, south vs. north, in central Spain . We established an experimental group (in which flower buds were clipped before anthesis) and a control group (undisturbed) in each site. We examined the seasonal variation in the resource level of the plants by sampling foliar nutrients (nitrogen and phosphorus), in four relevant phenological moments during reproduction. In the following reproductive season, we investigated the existence of costs of reproduction by assessing survival, reproductive output and growth. There were no significant differences in nutrient content between deblossomed and control plants. We detected costs of reproduction in terms of survival, but not in fecundity or growth. These results would explain to some extent the life strategy of this species, characterized by an intense reproduction “no matter what” and an extremely short life span (from four to six years), rather unusual for a perennial species in a semiarid environment.