Comparative Analysis of Population Structure of Gymnothorax Vicinus (Muraenidae) in the Northern Islands of Cabo Verde through Morphological Features and Genetic Markers

Abstract

Data from 10039 specimens of Gymnothorax vicinus (Castelnau 1855), commonly known as black moray eels, were sampled on the islands of São Vicente, Santa Luzia, and Santo Antão, between 2002 and 2020. The series of morphometric data were provided by the Institute of Marine Research in Cabo Verde - IMAR, as a result of 18 years of biological sampling of the species. Likewise, a total of 26 specimens were collected in the present study, analysed for genetic purposes, and sequenced the Cytochrome Oxidase I for genetic characterisation. The analysis of the length-weight relationships showed a significant difference between the islands, and the respective parameters of the correlation straight line (a and b) were 0.0019 and 2.95 for Santa Luzia, 0.0017 and 2.97 for São Vicente, and 0.0026 and 2.88 for Santo Antão, respectively. The trend for the Fulton K condition factor revealed that relatively high values were found between 2006 - 2007 and 2013 - 2014. For length-frequency distributions, significant differences were identified for smaller sample sizes as well as not significant between islands. With increasing sample size, the differences between islands disappeared. The differences in length-weight relationships between Santo Antão on one side and São Vicente and Santa Luzia on the other did not have repercussions on the analyses of genetic data. Of the 26 specimens aligned with data from Genbank, 18 haplotypes unique to Cabo Verde were found. Haplotype diversity was high, and nucleotide diversity was low. The haplotype network revealed the non-existence of a population genetic pattern in G. vicinus between these three islands, the haplotypes in Cabo Verde is very similar to each other. The only significant difference that was observed in the length-weight relationships could be related to the environmental influences of the habitats of these specimens.