Genetic structure of natural populations of Gelidium species: A re-evaluation of results

Abstract

Twenty-two loci were re-evaluated to assess genetic variation and differentiation in three natural populations (two from Gran Canaria and one from Tenerife) of Gelidium (G. canariensis and G. arbuscula). The new data using exclusively the diploid subpopulation gene frequencies confirm that dispersal was restricted over short distances for the two species, but contrary to previous conclusions, the data reveal that these two closely related species differed markedly by their mating systems and patterns of genetic differentiation. Genetic differentiation among populations was twice as high in G. arbuscula as in G. canariensis. It was confirmed that the mean way of reproduction is asexual in G. arbuscula and a discussion included as to how clonal propagation may explain the difference in haploid and diploid allele frequencies in this species. There was no evidence for asexual reproduction in G. canariensis. Heterozygote deficiency could be explained simply by spatial sub-structuring within populations. The importance of the sampling design in determining the level and pattern of genetic differentiation within a species is discussed.