Implications of mating system for genetic diversity of sister algal species:Fucus spiralisandFucus vesiculosus(Heterokontophyta, Phaeophyceae)

Abstract

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.

Fucus vesiculosus and spiralis species complex: a nested model of local adaptation at the shore level

“…4 mg of dried tissue using the Nucleospin® Multi-96 plant kit (Macherey-Nagel) according to the manufacturer's protocol and diluted 1:250. Polymerase chain reactions (PCR) on a MJ Research PTC200 thermocycler and electrophoresis of PCR products on a automated DNA sequencer (Li-Cor 4200) were performed for the 7 microsatellite loci L20, L38, L94, L58, L78, and fsp1, fsp2, as described, respectively, in Engel et al (2003) and Perrin et al (2007).…”

“…This may be important for the persistence of the high intertidal species F. spiralis, and data available to date suggest that selfing is predominant in this species (e.g. Billard et al 2005, Engel et al 2005, Perrin et al 2007, but see also Coleman & Brawley 2005).…”

Evolution and diversification within the intertidal brown macroalgae Fucus spiralis/F. vesiculosus species complex in the North Atlantic

“…One of the commonly occurring intertidal fucoids, and usually confined to the upper intertidal of rocky shores, is the desiccation-resistant (Davidson and Pearson, 1996), hermaphroditic and mainly self-fertilizing F. spiralis Perrin et al, 2007). Along eastern Atlantic shores in the northern hemisphere, F. spiralis (sensu lato) ranges from northern Norway to the Azores and Canary Islands, the latter being the southern-most record for the genus (Lüning, 1990;Haroun et al, 2002).…”

“…Morphological differences exist between the entities and each is subjected to different regimes of desiccation resistance (Billard et al, 2010;Zardi et al, submitted for publication). Although divergence of the habitat-specific ecotypes may have occurred by gradual adaptation of each entity to its respective micro-environment, the possibility of divergence of one entity from the other by hybridization/introgression with a co-occurring species cannot be discounted, especially as inter-specific gene flow is well documented within the genus Fucus (Wallace et al, 2004;Billard et al, 2005Billard et al, , 2010Engel et al, 2005;Coyer et al, 2006b;Mathieson et al, 2006;Perrin et al, 2007).…”

The mixed mating system of the sea palm kelpPostelsia palmaeformis: few costs to selfing

“…Some abundant brown algae species (such as the rockweed species of temperate shores) show high levels of selfing [17,18], while other species such as the giant kelp (Macrocystis pyrifera) self while also showing conspicuous inbreeding depression [22]. Despite estimates of spore dispersal for kelp in excess of 1 km [23,24] and spore viability for several days [25], many kelp spores settle near to the parental source, a feature that may lead to selfing in nature.…”