Sexual compatibility and hybrid formation between the giant kelp species Macrocystis pyrifera and M. integrifolia (Laminariales, Phaeophyceae) in Chile

Abstract

Two species of giant kelp inhabit the coast of Chile: Macrocystis integrifolia and M. pyrifera, representing important economic resources. As part of our efforts to domesticate these kelps for mariculture, and to obtain superior cultivars, we studied their biological relationship. Hybridization experiments with clonal gametophyte cultures showed reciprocal cross-fertility and produced fertile hybrid sporophytes with intermediate morphological characters. This hybridization potential in the laboratory contrasts with the persistence of two morphologically well-defined sister taxa in natural habitats on the Pacific coast of South America. We conclude that M. integrifolia and M. pyrifera are conspecific and speculate that unknown mechanisms support the co-existence of two morphologically distinct taxa on the subspecific level.