Genetic Diversity and Structure of Channel Catfish from Continental Waters of Mexico

Abstract

Mexico is the native site of 10 species of the genus Ictalurus, among which the Channel Catfish I. punctatus has great presence in worldwide aquaculture. Wild populations of catfish not only constitute a biological resource but have a great potential for aquaculture. Recently, this species was classified as an invasive organism by the Mexican government. The aim of this study was to determine the structure and genetic diversity of Channel Catfish belonging to native and introduced freshwater populations within Mexico. Using 11 DNA microsatellite loci, we analyzed 292 fish sampled from four rivers and five reservoirs. Observed heterozygosity values ranged between 0.66 and 0.80. The genetic distance analysis showed low to high differentiation among populations (overall genetic differentiation index FST = 0.14). Bayesian coancestry analysis identified two ancestral groups. A single management population on central Tamaulipas can be suggested. The findings of the present study provide the basis for future characterization of productive traits of Mexican Channel Catfish populations in order to use the species as a breeding source for aquaculture. The lower Rio Grande population is one of the most ancient and ecologically relevant Channel Catfish populations in Mexico, and this study identifies it as the most vulnerable. Free‐living populations of Channel Catfish, although they have been heedlessly spread, constitute a valuable natural resource that deserves our best effort to preserve.

Estimating the genetic diversity and potential influence of habitat segregation in Channel Catfish

“…Allelic richness of Channel Catfish from the Ottawa, Mississippi, and Madawaska rivers (5.7-6.1) was higher than that from Alabama hatchery populations (2.8-4.1; Lamkom et al 2008) and within the range of American Midwestern wild populations (5.4-6.5; Sotola et al 2017). Hatchery populations (10.6-10.9) and wild populations (8.2-16.3) from Tamaulipas, Mexico, however, were considerably more diverse than our study population (Parra-Bracamonte et al 2011;Lara-Rivera et al 2019). This is unsurprising given that population differentiation and speciation rates generally increase towards the equator (Mittelbach et al 2007;Freeman and Pennell 2021).…”

“…Channel Catfish sampled from Lac des Chats and its tributaries displayed low levels of inbreeding as evidenced by low F IS values between 0.001 and 0.058, comparable to wild Channel Catfish from the Ohio and Wabash rivers (0.008–0.115; Sotola et al 2017) and rivers throughout Mexico (0.006–0.065; Lara‐Rivera et al 2019). These low inbreeding levels indicate that the installation of both dams bordering Lac des Chats have not yet negatively impacted the genetic diversity of this population, even though they clearly prevent upriver movement.…”

Novel polymorphisms in Stearoyl‐CoA Desaturase (SCD) and Fatty Acid Desaturase 2 (FADS2) in channel catfish ( Ictalurus punctatus, Rafinesque, 1818 )

“…All these samples were previously assessed and described by Lara‐Rivera et al. (2019). DNA extraction was conducted using the GenElute Mammalian Genomic DNA Miniprep kit (SIGMA Aldrich, S. L. Missouri, USA).…”