Polyandry levels in Fucus vesiculosus

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Polymorphic microsatellite markers in the brown seaweed Fucus vesiculosus

Publication . Candeias, Rui; Casado-Amezúa, Pilar; Pearson, G. A.; Serrão, Ester; Teixeira, Sara

Background: Fucus vesiculosus is a brown seaweed dominant on temperate rocky shores of the northern hemisphere and, is typically distributed in the mid-upper intertidal zone. It is an external fertilizer that reproduces sexually, providing an excellent model to address conflicting theories related to mating systems and sexual selection. Microsatellite markers have been reported for several Fucus species, however the genomic libraries from where these markers have been isolated, have originated from two or more species pooled together (F. vesiculosus and F. serratus in one library; F. vesiculosus, F. serratus and Ascophyllum nodosum in a second library), or when the genomic DNA originated from only one species it was from Fucus spiralis. Although these markers cross-amplify F. vesiculosus individuals, the level of polymorphism has been low for relatedness studies. Findings: The microsatellite markers described here were obtained from an enriched genomic library, followed by 454 pyrosequencing. A total of 9 microsatellite markers were tested across 44 individuals from the North of Portugal. The mean number of alleles across loci was 8.7 and the gene diversity 0.67. Conclusions: The high variability displayed by these microsatellite loci should be useful for paternity analysis, assessing variance of reproductive success and in estimations of genetic variation within and between populations.

2015-03-08Journal article

Open access

Lack of fine-scale genetic structure and distant mating in natural populations of Fucus vesiculosus

Publication . Teixeira, Sara; Pearson, G. A.; Candeias, Rui; Madeira, Celine; Valero, Myriam; Serrão, Ester

Fine-scale spatial genetic structure (SGS) within populations reflects the dispersal behaviour of genes and individuals. Here we studied very small-scale SGS and mating patterns in the brown seaweed Fucus vesiculosus, a dioecious marine broadcast spawner with immediate settlement upon gamete release, which is predicted to strongly restrict gene flow. We estimated SGS, inbreeding and kinship for adults and recruits from habitats with contrasting exposures and patchiness (open coast and estuarine ecosystems) using microsatellite loci. Heterozygote deficiency was found for most adult populations but it was even higher for recruits, indicating inbreeding depression. At the fine spatial resolution of this study there was no spatial genetic structuring for 3 of the 5 populations studied across different habitats. Habitat could not explain the unrestricted gene flow in some populations. In the kinship analyses, we identified more putative mothers than fathers, suggesting that male gamete dispersal mediates gene flow at broader distances. However, the vast majority of the parents of the recruits could not be found among the adults sampled nearby, indicating unrestricted gene flow at these small scales. We propose 3 nonexclusive hypotheses for our findings: (1) unrestricted gene flow, (2) inbreeding depression eliminating most inbred individuals resulting from nearby related parents, (3) temporal Wahlund effects, mediated by a hypothetic genetic pool of a bank of microscopic forms persisting from previous generations.

2016-02Journal article

Open access