Johannesson & Johannesson (1993) contend that we have misread their earlier paper (Johannesson & Johannesson, 1990). They write that it is only possible to use neutral loci to study genetic relationships in closely related taxa (Johannesson & Johannesson, 1993) and that, there-fore, they had dismissed the variation in Aat-1 when considering the taxonomic status of Littorina neglecta (Johannesson & Johannesson, 1993). However, in their earlier paper they write: & ldquo;This [the pattern of variation in Aat-1] indicates that the within-site differentiation at Aat-1 is caused by diversifying selection in the two different micro-habitats rather than to a reproductive barrier between neglecta and saxatilis type snails” (Johannesson & Johannesson, 1990, p. 94). Therefore, after dealing separately with the pattern of variation at four loci which are ‘presumably neutral’ (Johannesson & Johannesson, 1990, p. 96), the Aat-1 variation is considered by these authors in the context of a putative reproductive barrier. The argument is repeated at the beginning of the discussion in Johannesson & Johannesson (1990, p. 95).
Pollen precedence in sexual Potentilla puberula and its role as a protective reproductive barrier against apomictic cytotypes
