Assessing the genetic diversity of the mangrove oyster Crassostrea rhizophorae (Bivalvia, Ostreidae) by microsatellite markers in southeastern Brazil

Abstract

Oysters of the genus Crassostrea are an economically important resource occurring along the Brazilian coast, mainly in estuarine regions. Inter- and intra-population genetic diversity is essential for monitoring long-term genetic changes and for sustainable use of this bivalve by coastal fishing communities. Microsatellite markers were used to evaluate the genetic diversity of natural populations of the mangrove oyster Crassostrea rhizophorae in southeastern Brazil. Samples of 150 oysters from four areas were analyzed. Microsatellite loci were obtained from an enriched microsatellite library. The genetic structure was evaluated using an index of genetic differentiation described previously. The effective population size and rate of gene flow were estimated through a maximum likelihood coalescent approach using Migrate. The mean number of alleles ranged from 10 to 21 and the expected heterozygosity from 0.89 to 0.91. Evidence of a possible bottleneck effect under three mutational models was found. The D _est index indicated low to moderate differentiation among sample locales. Coalescent analysis showed variation in effective population size and asymmetry in the gene flow among samples. Levels of genetic variability and differentiation found among C. rhizophorae populated banks have important implications for the sustainable harvest, cultivation and conservation of this marine resource in the studied area.

Key words:

• Genetic diversity
• estuarine system
• mangrove oyster
• population structure
• STR

Acknowledgements

We thank Dr Marcelo Barbosa Henriques for his help with sampling and fieldwork logistics, Messrs Onésio Veríssimo and Antônio Pires for their help during oyster sampling, Dra Celina Maria Marcondes Pimentel and Ms Delcira de Fátima Santos Vieira for their assistance during oyster processing, and Vívian Uhlig, MSc for map-drawing. This work was developed as part of the full requirements for the PhD Thesis in Biotechnology at the University of Mogi das Cruzes/Fundação de Amparo ao Ensino e Pesquisa.

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplementary material (Table SI)

The supplementary material for this article is available via the Supplemental tab of the article’s online page at http://dx.doi.org/10.1080/17451000.2015.1047381

Additional information

Funding

We would like to thank the São Paulo Research Foundation (FAPESP # 07/50094–0) for granting funds to support this project.