Date of Award

2019

Degree Type

Thesis

Degree Name

Master of Science in Biological and Environmental Sciences (MSBES)

Specialization

Cell and Molecular Biology (CMB)

Department

Cell & Molecular Biology

First Advisor

Marta Gomez-Chiarri

Abstract

Marine fishes represent a valuable resource for the global economy and food consumption, but many species experience high levels of exploitation necessitating effective management plans. Long term sustainability of these resources may be jeopardized from insufficient knowledge about intra-specific population structure. Restriction-site associated DNA sequencing (RAD-seq) methods are revolutionizing the field of population genomics in non-model organisms as they can generate a high number of single nucleotide polymorphisms (SNPs) even when no reference genomic information is available. Sardinella aurita and Sardinella maderensis are non-model species lacking reference genomes. Using double-digest restriction-site associated DNA (ddRAD) sequencing, we surveyed variation in 6,078 single nucleotide polymorphisms (SNPs) loci identified in S. aurita from Mauritania, Senegal, Ghana, Togo, and Benin in West Africa and 6,767 SNPs loci identified in S. maderensis from Mauritania, Senegal, Guinea, Togo, and Benin.

Sardinella aurita populations revealed low levels of genetic differentiation (overall FST value = 0.001 and pairwise FST values ranging from -0.002 to 0.005, p > 0.05) and lack of population structure at the geographic locations surveyed, suggesting the presence of a single panmictic population in this region. Analysis of S. maderensis samples also demonstrated that genetic differentiation does not exists across the locations studied (overall FST = 0.002, and pairwise FST values ranged from -0.005 to 0.016). More research needs to be performed to extend the geographical and temporal sampling. Overall, results from this research will contribute to our understanding of the distribution of the two species to assist in the management of the fish resources in the Eastern Central Atlantic region (CECAF) of the Food and Agriculture Organization (FAO).

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