The implications of mating system for genetic diversity were assessed in the sister species Fucus spiralis and Fucus vesiculosus using a combination of ten microsatellite markers. Five new microsatellite markers specific for F. spiralis were developed in order to increase marker resolution and complement the results (i.e. mating system and genetic diversity extended to a larger geographic scale) acquired using five microsatellite loci previously developed from a mixed fucoid seaweed DNA library that excluded F. spiralis. Low genetic diversities observed at the population and species level in F. spiralis using the five new F. spiralis-specific loci described here were consistent with the results obtained previously with non-specific microsatellite loci. Results revealed that selfing is characteristic in F. spiralis across its latitudinal distribution along the Iberian and French Atlantic coasts. Higher levels of within-population genetic diversity were observed in the outcrossing species F. vesiculosus, decreasing towards the southern distributional range of the species. Some cases of significant biparental inbreeding in this species are indicative of short gamete dispersal or mating of spatially or temporally structured populations. In contrast to within-population diversities, higher total genetic diversity among populations was observed in the hermaphroditic species in comparison to the dioecious F. vesiculosus.

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The Eurasian badger Meles meles has a wide distribution area ranging from Japan to Ireland. In western Europe badger habitats are severely disturbed by anthropogenic factors, leading to fragmentation into subpopulations and formation of a metapopulation substructuring of once continuous panmictic populations. We have examined the genetic structure of Dutch and Danish badger populations on a relatively small scale (within countries) and a larger scale (between countries). The levels of genetic variation of populations were moderate and did not differ significantly among populations (overall H O = 0.30, overall H E = 0.34). Considerable genetic differentiation between the Dutch and Danish populations was found (overall F ST = 0.32, mean pairwise Dutch-Danish F ST = 0.42), indicating a largescale substructuring of these western European badger populations. Further analysis showed that the Danish badger population can be substructured into three clusters [P (k =3) = 0.99], but the Dutch populations cluster into one more or less panmictic population [P (k =1) = 0.99] with little or no substructuring. The presence of migration barriers, such as roads, together with the peninsular geography of Denmark, may have led to this structuring of badger populations. In contrast, measures that improve migration and connection to other populations from neighboring countries may have prevented substructuring of the Dutch badger population.