Abstract The spotted rose snapper, Lutjanus guttatus, is an important fishery species with high potential for aquaculture. Genetic characterization of its natural populations is necessary to avoid stock collapse and loss of genetic diversity. Previous studies carried out in the Tropical Eastern Pacific (TEP), however, have shown contrasting results in the genetic structure of fish populations, particularly in species of Lutjanidae. Therefore, to understand the genetic structure of spotted rose snapper in the TEP, twelve microsatellite loci were used to assess the genetic diversity and explore the hypothesis of population genetic structure in samples of the species collected throughout the TEP. Fin clips from 186 sampled individuals (27 to 49 per site) were analyzed from five sites in the three regional biogeographic provinces, delimited by shoreline reef habitat breaks: La Paz (Cortez province), Colima and Oaxaca (Mexican province), Chiriqui and Port of Panama (Panamic province). Results of global Analysis of Molecular Variance (AMOVA), population pairwise FST, hierarchical AMOVA, and a discriminant analysis of principal components (DAPC) reflected a panmictic population involving the entire set of sampled sites. The role of larval dispersal, post-recruitment migration, and marine current dynamics as drivers of genetic connectivity in this species is discussed.

Resumen El pargo lunarejo, Lutjanus guttatus, es una importante especie pesquera, con alto potencial para la acuicultura. La caracterización genética de sus poblaciones naturales es necesaria para evitar el colapso del stock y la pérdida de diversidad genética. Sin embargo, estudios previos realizados en el Pacífico Oriental Tropical (TEP), han mostrado resultados contrastantes en la estructura genética de poblaciones de peces, particularmente en especies de Lutjanidae. Por lo tanto, para entender la estructura genética del pargo lunarejo en el TEP, se usaron 12 loci microsatélites para evaluar la diversidad genética y explorar la hipótesis de estructura genética poblacional en muestras de la especie colectada a lo largo del TEP. Se analizaron fragmentos de aletas de 186 individuos (27 a 49 por sitio) de cinco localidades en las tres provincias biogeográficas regionales, delimitadas por las discontinuidades de hábitat de arrecife costero: La Paz (Provincia de Cortés), Colima y Oaxaca (Provincia Mexicana), Chiriquí y Puerto de Panamá (Provincia Panámica). Los resultados del Análisis de Varianza Molecular (AMOVA) global, FST de poblaciones pareadas, AMOVA jerárquico y un análisis discriminante de componentes principales (DAPC) reflejaron una población panmíctica que involucraba todo el conjunto de sitios muestreados. Se discute el papel de la dispersión larvaria, migración post-reclutamiento y la dinámica de las corrientes marinas como propulsores de la conectividad genética en esta especie.

ABSTRACT Cherax quadricarinatus is a decapod crustacean of interest to the aquaculture industry. In Mexico, a significant effort has been made to improve biological requirements, but the genetic characteristics are unknown. We examined the genetic diversity and differentiation in four populations in Mexico (three commercial farms and one feral population), as well as one research line from Argentina, used as reference. To initiate a founder stock in a genetic improvement program, we analyzed five microsatellite markers. The genetic diversity in terms of the number of alleles was low to moderate (2.8-6.2) in Mexican populations than the Argentinean sample (8.8). A pairwise Wright's Fst analysis showed that all populations were significantly different (P < 0.5). Cross-breeding organisms from a different population are suggested to increase genetic variability before initiating a founder stock with higher genetic variation.

ABSTRACT The spotted rose snapper Lutjanus guttatus is a fishery relevant species from the eastern Pacific Ocean, with aquaculture potential. Species-specific genetic markers are needed for the genetic characterization of wild and cultivated populations to help management strategies. Eighteen hypervariable microsatellites were developed by Next Generation Sequencing and characterized in a wild population sample. Genetic diversity was high (observed heterozygosity = 0.88 ± 0.050; the number of alleles per locus = 13.4 ± 1.3) and few loci departed from the Hardy-Weinberg Equilibrium, leaving 14 loci potentially suitable for population genetic studies. A reduced panel of five loci was tested in a cultivated stock to determine the parentage of progeny (embryonated eggs; n = 413), to estimate the temporal contribution of each parental broodstock. The above resulted in the successful assignment of 95.6% of the progeny to its parental couple, representing 17 out of the 24 possible families. Two of the four females produced most of those progeny (97.3%). These females, which reproduced throughout the season, did not spawn on consecutive days. The contribution of males was evenly distributed during the season and occurred on successive days. Some microsatellites can be used in other lutjanids (L. peru, L. argentiventris, and Hoplopagrus guentherii).

Resumen La liberación o escape de lotes de cultivo pueden impactar la composición y variabilidad genética de las poblaciones silvestres, dando lugar a diversos problemas que pueden comprometer la eficacia biológica a largo plazo. Por lo tanto, es relevante determinar si las poblaciones de cultivo se encuentran actualmente interactuando con las poblaciones silvestres. El cultivo de camarón es una actividad de acuicultura que tiene lugar a lo largo de la costa del Pacífico tropical de América, y es la más importante en el noroeste de México. En este estudio, el camarón blanco Litopenaeus vannameisilvestre y de cultivo proveniente del Estado de Sinaloa, México, fueron evaluados genéticamente para determinar los niveles de mezcla. Se desarrolló un lote de 14 marcadores microsatélites nuevos (número de alelos promedio por locus de 11.8 y heterocigosidad esperada promedio de 0.836), mediante secuenciación de nueva generación, para la caracterización de las muestras. El muestreo consistió en camarón silvestre recolectado durante tres años (2002, 2012 y 2013) y dos lotes de unidades productoras de larva del 2007. No se observaron diferencias significativas entre años en las muestras silvestres, pero el análisis de agrupamiento indicó que los lotes de las unidades productoras de larva fueron distintos a los ejemplares silvestres. Desviaciones del equilibrio de Hardy-Weinberg y los análisis de asignación de genotipos indicaron que una fracción de cada una de las muestras silvestres podría contener individuos originados del larvicultivo. Se discuten las razones que explican la liberación de camarón de cultivo intencional y no intencional al medio silvestre. Aun cuando la fracción estimada de individuos de origen de cultivo en las muestras silvestres más recientes (2012-2013; promedio = 7.1 %) se considera de bajo riesgo, se dan recomendaciones de manejo para unidades de larvicultura y granjas de cultivo.

Abstract Release or escapes of aquaculture organisms may impact the genetic composition and variability of wild populations, leading to diverse issues that may compromise long-term wild stock fitness. Therefore, it is relevant to determine if farmed stocks are currently interacting with wild populations. Shrimp farming is an aquaculture activity taking place along the tropical Pacific coast of the Americas, and represents the most important culture business of Northwestern Mexico. In this study, wild and farmed whiteleg shrimp Litopenaeus vannamei from the State of Sinaloa were genetically evaluated to determine admixture levels. A newly developed set of 14 microsatellite markers (mean number of alleles per locus 11.8, and 0.836 expected heterozygosity) was obtained by Next Generation Sequencing to characterize samples. Sampling consisted of 32 wild shrimps collected during three years (2002, 2012, and 2013) and three different sites, and two hatchery stocks from 2007. No significant differences were observed among years in the wild samples, but cluster analyses showed that hatchery-produced individuals were different from wild specimens. Deviations from Hardy-Weinberg Equilibrium and genotype assignment tests indicated that a fraction from each sample could contain individuals from hatchery origin. Even though the estimated fraction of escaped farmed individuals in the most recent samples (2012-2013; mean = 7.1 %) is considered of low genetic risk, management recommendations for hatcheries and farms were provided. Besides, the reasons that explain the intended and unintended farmed shrimp release into the wild were discussed. Rev. Biol. Trop. 66(1): 381-393. Epub 2018 March 01.

Abstract: To increase productivity, genetic improvement in cultivated shrimp is of much interest. Evaluation of genetic parameters (e.g., heritability, genotype-environment interaction, inbreeding) and the design of appropriate breeding plans are necessary steps towards genetic improvement. Pedigree traceability by genetic markers is relevant to these objectives. The aim of this study was to compare the performance of 2 genetic marker panels (microsatellites and single nucleotide polymorphisms [SNPs]) for pedigree traceability of a cultivated stock of whiteleg shrimp (Litopenaeus vannamei). Pedigree of a stock from 81 full-sib families reared in a common environment was assessed with microsatellites and SNPs as genetic markers. The panel of 76 SNPs performed better than microsatellites, allowing 94-96% of parentage assignment of the tested progeny (n = 192). A minimum number of 50 SNPs with a proportion of 60% loci with a minimum allele frequency of 0.3 is suitable for successful pedigree assignment. SNP markers are suggested for confidently testing the pedigree of shrimp from known parental broodstock.

Resumen: El mejoramiento genético en el camarón cultivado es de amplio interés para incrementar la productividad. La evaluación de parámetros genéticos (e.g., heredabilidad, interacción entre genotipo y ambiente, endogamia) y el diseño de planes de apareamiento son elementos necesarios para el mejoramiento genético. La rastreabilidad del pedigrí con marcadores genéticos es importante para estos objetivos. El objetivo de este trabajo fue comparar el desempeño de 2 paneles de marcadores genéticos (microsatélites y polimorfismos de nucleótido sencillo [SNP]) para rastrear el pedigrí en una población de camarón blanco (Litopenaeus vannamei) de cultivo. Se determinó el pedigrí de la progenie de 81 familias de hermanos completos mediante el uso de microsatélites y SNP como marcadores genéticos. Un panel de 76 SNP probó tener un mejor desempeño que los microsatélites para la asignación de parentesco, obteniéndose un 94-96% de asignación en una muestra de la progenie (n = 192). Un número mínimo de 50 SNP con una proporción de 60% de loci con una frecuencia alélica mínima de 0.3 es adecuado para una asignación exitosa de pedigrí. Se sugiere utilizar los marcadores SNP para determinar el parentesco de la progenie de camarón proveniente de padres conocidos.