The Effect of Intra- and Inter-Specific Competition on Growth of the Invasive Carpobrotus Edulis Under Different Nutrient Levels

Abstract

[Abstract] Competition for resources is one of the most important interactions affecting population dynamics and community structure. This study investigates the differences between three types of competition in the invasive clonal species Carpobrotus edulis: intra-clone (two identical genotypes of C. edulis), inter-clone (two different genotypes of C. edulis) and inter-specific (one individual of C. edulis and one individual of C. aff. acinaciformis) competition. In addition, it is determined whether the soil nutrients availability affects the different types of competition. The results showed a negative effect of inter-clone and inter-specific competition. However, there was no intra-clone competition, indicating the presence of a self-recognition mechanism between identical genotypes of C. edulis. This result may have important consequences on the invasive success of the species studied. Carpobrotus edulis expands forming large clumps of genotypically identical individuals. Intra-clone competition migh favour the successful expansion of this invasive species. The results did not find any significant effect of nutrient availability on the types of competition tested. However, there was a tendency for the negative impact of inter-clone and inter-specific competition to be more pronounced in the high nutrient treatment.