Adaptive traits regulating dormancy and germination of invasive species

Abstract

AbstractWeed invasion in cropland can be estimated by measuring specific constancy (Number of fields of occurence/Number of fields surveyed). Since the beginning of this century, many floristic surveys have been carried out in fields with similar soil types in the Pampas of Argentina. Thus, weed species with high constancy in maize or wheat crops over more than 60 years could be identified. Convergence among species of any trait having a selective advantage in the cropping environment would be expected. However, no evidence of such convergence was found in seed bank persistence or in dormancy and germination characteristics of summer or winter annuals selected as model species: Amaranthus retroflexus, Datura ferox, Echinochloa crus‐galli, Tagetes minuta, Avena fatua, Galinsoga parviflora. On the other hand, changes in dormancy and germination traits were recorded in seeds of E. crus‐galli and A. fatua in different agricultural systems, suggesting an adaptive value for invasion of human disturbed habitats. We used a simulation approach to investigate the importance of ecophysiologic seed phenotypes for the invasion of plants into specific human disturbed habitats. Results of the simulations showed that rainfall pattern and soil type interactions changed relative fitness of the tested phenotypes.