Genetic structure of Mexican golden trout defined by GBS methods.

Authors: Marco A. Escalante, Francisco J. Garcia-De Leon, Charles Perrier, Arturo Ruiz-Luna, Stephanie Manel

Year: 2016 (xlviii)

Abstract

Mexican golden trout (Oncorhynchus chrysogaster) is an endemic species that inhabits Fuerte; Sinaloa and Culiac’n basins in Northwestern Mexico and represents one of the salmonid species with southernmost distribution in the world. Mexican golden trout originates from a coastal anadromous trout during Pleistocene, being isolated in the high mountains of different watersheds in the western part of mainland Mexico. O. chrysogaster range is reduced to the highest parts of the mountains, and this species is threatened by several anthropogenic and environmental factors; climatic global change and mainly the introduction of the exot ic rainbow trout (Onchorhynchus mykiss) with aquaculture purposes. Recent works have divided Mexican golden trout in different genetic populations, however, these studies have been conducted with few neutral genetic markers. With the development of a greater number of markers Next Generation Sequencing opens the possibility to investigate more subtle genetic structure, and to detect both neutral and adaptive genetic variation (Allendorf et al. 2010). In this study, 271 Mexican golden trout and 24 cu ltured rainbow trout samples were collected at 27 sites in Northwestern Mexico. Genotyping by Sequencing (GBS) technics produced 10,000 SNPs markers for the 285 individuals analyzed. Population genetics analyses were performed through neighbor joining methods and assignment tests (Jombart 2008; Raj et al. 2014). Those analyses highlighted six different genetic clusters for Mexican golden trout and few native populations showed signal of genetic introgression from cultured rainbow trout. Analyzes of gene flow and effective population size are in process. Considering the importance of the genetic legacy of O. chrysogaster conservation efforts should increase preserving its habitat and biodiversity, in the same way aquaculture activities with exotic trout on its distribution area must be stopped. Our results will help to propose conservation strategies.