Population genetic structure of the endemic fish Gambusia marshi from the Cuatro Ciénegas basin and its outflow in Coahuila, Mexico

Abstract

1. The valley of Cuatro Ciénegas in Coahuila, Mexico, has the highest degree of local endemism of any habitat in North America. Despite the arid desert climate, the basin harbours an extensive system of permanent streams, wetlands, and springfed pools, and is divided into two sub-basins by the central Sierra de San Marcos y Pinos.2. Microsatellite loci were surveyed to infer the genetic diversity and population structure of Gambusia marshi, a poeciliid fish endemic to the Cuatro Ciénegas basin and the Río Salado de Nadadores in north-east Mexico.3. Bayesian clustering analysis revealed four genetic populations within G. marshi and a major east-west division corresponding to the Sierra de San Marcos y Pinos.

Out to sea: ocean currents and patterns of asymmetric gene flow in an intertidal fish species

“…While our discussion is focused on broad scale clustering results (K = 8), an AMOVA suggests significant population structure between regions (Central America, Bahamas, South Florida, West Florida, East Florida), populations within regions, sampling locations within populations, individuals within sampling locations, and within individuals ( Table 1 ). Strong population structure is common in intertidal fish ( Díez-del-Molino et al, 2016 ; Hurt et al, 2017 ; Xie et al, 2022 ) and species occupying highly fragmented landscapes ( Browne et al, 2015 ; Wultsch et al, 2016 ). We also expect strong population structure in mixed-mating species ( Mori et al, 2015 ), those that can outcross or self-fertilize, with more structure emerging as outcrossing rates decrease ( Duminil, et al, 2007 ; Hodgins and Yeaman, 2019 ).…”