Evaluation of Microsatelite loci in Largemouth Bass (Micropterus salmoides): Resolution of Population Structure and Individual Origins




Lutz-Carrillo, Dijar J.

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Microsatellite DNA variation was evaluated for the first time within the largemouth bass (Micropterus salmoides). Eleven of forty-five primer pairs, originally developed for the amplification of microsatellite loci in other centrarchid species, were found to be suitably polymorphic, or expressed conserved differences in allele frequencies between subspecies of M salmoides (HE = 0.407), for utilization in this study. Based on genetic variation at these loci and concurring measures of genetic distance and differentiation, multiple ANOV A analyses, and Bayesian inference techniques, population structure within the species was resolved as consisting of three genetic assemblages with M. s. floridanus (Florida largemouth bass) in peninsular Florida, and M. s. salmoides (Northern largemouth bass) at northern and southern latitudes within North America. Furthermore, samples from the Devil's River (southwest Texas) expressed unique allele frequencies at four of eleven loci. This fine scale genetic resolution has not previously been reported within the species and, given previous reports of morphologically distinct characteristics for the Devil's River population, suggests the unique nature of this group within M. salmoides. Additionally, a new method for probabilistically assessing the subspecific, regional and in some cases the population status, and genomic composition, of individuals within the species, allowing the correct assignment of 99% to 100% of individuals is provided. Although subspecies were confidently resolved, high levels of introgression would greatly complicate the process of identification. Simulation studies indicated that the clustering values of intergrades approach those of pure subspecies after two parental backcrosses from an F 1 generation. Microsatellite loci were also assessed for their utility in assigning multilocus fingerprints to individuals. Among 473 individuals, no duplicate genotypes were identified, but β-error probabilities ranged from 2.8 x 10-3 to 2.7 x 10-7 within populations. These relatively high levels of duplication and large number of loci required would limit the practicality of this application, but levels of polymorphism at two loci, Lma021 and Lar007, suggest that the future identification of other highly polymorphic loci will make fingerprinting and thus the unique identification of individuals feasible.



Largemouth bass, Microsatellites, Genetic polymorphisms, Fishery management


Lutz-Carrillo, D. J. (2004). <i>Evaluation of microsatelite loci in largemouth bass (Micropterus salmoides): Resolution of population structure and individual origins</i> (Unpublished thesis). Texas State University-San Marcos, San Marcos, Texas.


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