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MEPS prepress abstract   -  DOI: https://doi.org/10.3354/meps14171

Exploring the Genetic Diversity and Population Structure of Mobula birostris in Two Key Aggregation Zones in the Eastern Tropical Pacific

Karla E. Rojas López, Juan José Guadalupe, Milton Andrés Gordillo, Andrea Montero-Oleas, Diana A. Pazmiño, Michel Guerrero, Maria de Lourdes Torres*

*Corresponding author:

ABSTRACT: Mobula birostris is the largest ray species in the world. Little is known about its genetic composition in key aggregation sites such as the Galapagos Islands and Isla de la Plata, near the province of Manabi in mainland Ecuador. This study aimed to determine the genetic diversity and population structure of M. birostris in these two locations to better understand the connectivity and distribution of M. birostris in Ecuadorian oceanic waters and to assist in its conservation and appropriate management. A total of 127 samples from mainland Ecuador (2013-2018) and 21 samples from Galapagos (2019) were collected and analyzed using eight microsatellite loci. Results showed a moderately high level of genetic diversity for giant manta rays in both sites (mainland Ecuador He=0.72; Galapagos He= 0.66). Population structure analyses suggested the presence of two different populations between Galapagos and mainland Ecuador. The different genetic composition found for each location could be associated to resident behavior displayed by giant manta rays, linked to the formation of upwelling systems caused by oceanic currents that bring nutrient-rich waters to both sites year-round. Our genetic connectivity analysis confirmed low gene flow between these two locations, further rejecting the hypothesis of a single panmictic population of M. birostris in Ecuador. All together, these results provide valuable information about the genetic composition and diversity of the giant manta ray, an endangered species which has been scarcely studied in the Eastern tropical Pacific.