ABSTRACT
Variance components and heritabilities for daily weight gain (DWG) were estimated for Nile tilapia farmed in cages across nine generations (G1-G9) of selection in a breeding program in Brazil. DWG was measured in 16,272 accumulated tagged animals representing 535 full- and half-sib families of Nile tilapia under cage farming. The additive genetic variance showed a slight variation (0.051-0.066), and heritability estimates ranged from 0.20 to 0.33. The common environmental effect accounted for a higher proportion of the total variance in DWG, especially in the last generations (6%-24%). A genetic trend based on all data available showed a substantial increase in the DWG (about 3.3% per generation) of Nile tilapia across nine generations of selection. Furthermore, our results demonstrate ample scope for further genetic improvement.
Subject(s)
Cichlids , Animals , Brazil , Cichlids/genetics , Weight GainABSTRACT
Jewel tetra (Hyphessobrycon eques) is a freshwater fish found in several rivers and basins in South America. The present study is the first study to create a panel of microsatellite markers for detecting genetic diversity in H. eques and evaluating the application of these markers in Serrapinnus notomelas. In total, 44 individuals were genotyped from the natural (WIL, n = 20) and stock in captivity (CAP, n = 24) population. Moreover, 19 microsatellite markers were obtained, of which only 8 loci presented a high degree polymorphism. In total, 45 alleles were detected, ranging from 126 bp (Hype2G2) to 420 bp (Hype2E2). The Hardy-Weinberg equilibrium (p < 0.05) revealed significant difference in one locus in WIL (Hype1G4) and three loci in CAP (Hype1F4, Hype2C3, and Hype2G2). Null alleles (p < 0.05) were present in only one locus (Hype1G4). The WIL and CAP populations revealed high genetic diversity during FST analysis. The cross-amplification test for S. notomelas revealed that only two loci (Hype2C3 and Hype2G2B) presented satisfactory transferability results. The developed microsatellite primers will be useful in studying the genetic diversity and population structure of H. eques in wild populations and fish farms in the Brazilian and other South American basins.
Subject(s)
Genetics, Population , Microsatellite Repeats , Alleles , Animals , Genetic Variation/genetics , Genotype , Microsatellite Repeats/genetics , Polymorphism, GeneticABSTRACT
With the rise of world fish farming, the national scenario is favorable for using native fish for intensive farming. Among the catfish, the Amazonian Jundiá (Leiarius marmoratus) is a robust candidate, easy to grow and with good organoleptic characteristics in its flesh. For productive success in captivity, it is necessary to consider some questions about the species, such as genetic variability, which must have an acceptable level in a breeding stock, in order to maintain a good diversity; this reduces losses due to inbreeding and low diversity. Therefore, the objective of this study was to characterize the genetic variability of commercial stocks of L. marmoratus from the State of Mato Grosso through microsatellite molecular markers. We analyzed 143 individuals from three stocks. The mean heterozygosity and the inbreeding coefficients observed were 0.060; 0.084; 0.141; and 0.539; 0.562; 0.514, respectively, for the stocks of Campo Verde, Juína, and Nova Mutum. The Deviation in the Hardy-Weinberg equilibrium was observed in most of the loci in the three populations. Considering the genetic differentiation, it is concluded that the three populations are very close genetically, which requires introduction of new genetic material in the stocks to enrich them genetically for a later reproductive program.(AU)
Subject(s)
Animals , Genetic Variation , Catfishes/genetics , Genetic Markers , FisheriesABSTRACT
With the rise of world fish farming, the national scenario is favorable for using native fish for intensive farming. Among the catfish, the Amazonian Jundiá (Leiarius marmoratus) is a robust candidate, easy to grow and with good organoleptic characteristics in its flesh. For productive success in captivity, it is necessary to consider some questions about the species, such as genetic variability, which must have an acceptable level in a breeding stock, in order to maintain a good diversity; this reduces losses due to inbreeding and low diversity. Therefore, the objective of this study was to characterize the genetic variability of commercial stocks of L. marmoratus from the State of Mato Grosso through microsatellite molecular markers. We analyzed 143 individuals from three stocks. The mean heterozygosity and the inbreeding coefficients observed were 0.060; 0.084; 0.141; and 0.539; 0.562; 0.514, respectively, for the stocks of Campo Verde, Juína, and Nova Mutum. The Deviation in the Hardy-Weinberg equilibrium was observed in most of the loci in the three populations. Considering the genetic differentiation, it is concluded that the three populations are very close genetically, which requires introduction of new genetic material in the stocks to enrich them genetically for a later reproductive program.
With the rise of world fish farming, the national scenario is favorable for using native fish for intensive farming. Among the catfish, the Amazonian Jundiá (Leiarius marmoratus) is a robust candidate, easy to grow and with good organoleptic characteristics in its flesh. For productive success in captivity, it is necessary to consider some questions about the species, such as genetic variability, which must have an acceptable level in a breeding stock, in order to maintain a good diversity; this reduces losses due to inbreeding and low diversity. Therefore, the objective of this study was to characterize the genetic variability of commercial stocks of L. marmoratus from the State of Mato Grosso through microsatellite molecular markers. We analyzed 143 individuals from three stocks. The mean heterozygosity and the inbreeding coefficients observed were 0.060; 0.084; 0.141; and 0.539; 0.562; 0.514, respectively, for the stocks of Campo Verde, Juína, and Nova Mutum. The Deviation in the Hardy-Weinberg equilibrium was observed in most of the loci in the three populations. Considering the genetic differentiation, it is concluded that the three populations are very close genetically, which requires introduction of new genetic material in the stocks to enrich them genetically for a later reproductive program.
ABSTRACT
With the rise of world fish farming, the national scenario is favorable for using native fish for intensive farming. Among the catfish, the Amazonian Jundiá (Leiarius marmoratus) is a robust candidate, easy to grow and with good organoleptic characteristics in its flesh. For productive success in captivity, it is necessary to consider some questions about the species, such as genetic variability, which must have an acceptable level in a breeding stock, in order to maintain a good diversity; this reduces losses due to inbreeding and low diversity. Therefore, the objective of this study was to characterize the genetic variability of commercial stocks of L. marmoratus from the State of Mato Grosso through microsatellite molecular markers. We analyzed 143 individuals from three stocks. The mean heterozygosity and the inbreeding coefficients observed were 0.060; 0.084; 0.141; and 0.539; 0.562; 0.514, respectively, for the stocks of Campo Verde, Juína, and Nova Mutum. The Deviation in the Hardy-Weinberg equilibrium was observed in most of the loci in the three populations. Considering the genetic differentiation, it is concluded that the three populations are very close genetically, which requires introduction of new genetic material in the stocks to enrich them genetically for a later reproductive program.
With the rise of world fish farming, the national scenario is favorable for using native fish for intensive farming. Among the catfish, the Amazonian Jundiá (Leiarius marmoratus) is a robust candidate, easy to grow and with good organoleptic characteristics in its flesh. For productive success in captivity, it is necessary to consider some questions about the species, such as genetic variability, which must have an acceptable level in a breeding stock, in order to maintain a good diversity; this reduces losses due to inbreeding and low diversity. Therefore, the objective of this study was to characterize the genetic variability of commercial stocks of L. marmoratus from the State of Mato Grosso through microsatellite molecular markers. We analyzed 143 individuals from three stocks. The mean heterozygosity and the inbreeding coefficients observed were 0.060; 0.084; 0.141; and 0.539; 0.562; 0.514, respectively, for the stocks of Campo Verde, Juína, and Nova Mutum. The Deviation in the Hardy-Weinberg equilibrium was observed in most of the loci in the three populations. Considering the genetic differentiation, it is concluded that the three populations are very close genetically, which requires introduction of new genetic material in the stocks to enrich them genetically for a later reproductive program.
ABSTRACT
With the rise of world fish farming, the national scenario is favorable for using native fish for intensive farming. Among the catfish, the Amazonian Jundiá (Leiarius marmoratus) is a robust candidate, easy to grow and with good organoleptic characteristics in its flesh. For productive success in c aptivity, it is necessary to consider some questions about the species, such as genetic variability, which must have an acceptable level in a breeding stoc k, in order to maintain a good diversity; this reduces losses due to inbreeding and low diversity. Therefore, the objective of this study was to characterize the genetic variability of commercial stocks of L. marmoratusfrom the State of Mato Grosso through microsatellite molecular markers. We analyzed 143 individuals from three stocks. The mean hete rozygosity and the inbreeding coefficients observed were 0.060; 0.084; 0 .141; and 0.539; 0.562; 0.514, respectively, for the stocks of Campo V erde, Juína,and Nova Mutum. The Deviation in the Hardy-Weinberg equilib rium was observed in most of the lociin the three populations. Considering the genetic differentiation, it is concluded that the three populations are very clo se genetically, which requires introduction of new genetic material in the stock s to enrich them genetically for a later reproductive program.(AU)
Subject(s)
Animals , Catfishes/genetics , Genetic Variation , DNA Primers/analysisABSTRACT
Digital image analysis is a practical, non-invasive, and relatively low-cost tool that may assist in the evaluation of body traits in Nile tilapia, being particularly useful for assessing difficult-to-measure variables, such as body areas. In this study, we aimed to estimate variance components and genetic parameters for body areas of Nile tilapia obtained by digital images. The data set comprised body weight (BW) records of 1,917 pond-reared fish at 366 days of age. Of this total, 656 animals were photographed and subjected to image analysis of trunk area (TA), head area (HA), caudal fin area (CFA) and fillet area (FA). Heritabilities and genetic correlations were estimated through multiple-trait models based on Bayesian inference. Heritability estimates for BW, TA, HA, CFA and FA were 0.25, 0.23, 0.26, 0.21 and 0.25, respectively. Genetic correlations between the traits were high and positive, ranging from 0.70 to 0.98. We highlight the genetic correlation between BW and TA (rG = 0.98) and FA (rG = 0.97). In view of the observed results, it can be concluded that trunk and fillet areas obtained by digital image analysis can lead to indirect genetic gains in weight and other body areas. In addition, the areas studied have potential as a selection criterion and may assist in studies on changes in the body shape in Nile tilapia.
Subject(s)
Cichlids , Animals , Bayes Theorem , Body Weight , Cichlids/genetics , PhenotypeABSTRACT
Nile tilapia (Oreochromis niloticus) is the major fish species produced in Brazil, a country with a vast territory and great climate diversity. This study assessed the effects of the genotype × environment interaction on heritability estimates and selection responses in Nile tilapia (Tilamax strain) cultivated in earthen ponds and net cages. The weight at harvest, trunk length, and head percentage of 4400 individuals were determined. Trait heritabilities were higher in pond fish (0.27-0.52) than in caged fish (0.09-0.33). Genetic correlations between farming systems were lower than 0.5 for the three traits. The rank position of the top 10 families differed according to the environment, as did the response to direct and indirect selection. The results revealed significant genotype × environment effects on the heritability of Nile tilapia farmed under different systems.
Subject(s)
Body Weight/genetics , Gene-Environment Interaction , Tilapia/genetics , Animals , Aquaculture , Brazil , Genotype , Phenotype , Tilapia/growth & developmentABSTRACT
In this paper, we introduce a class of continuous time dynamical planar systems that is capable of generating attractors in the plane by means of the use of hysteresis and at least two unstable foci. This class of systems shows stretching and folding behavior due to unstable equilibria and hysteresis. Hysteresis is used to overwhelm the constraints on the behavior of planar systems. This class of systems is derived from three-dimensional piecewise linear systems that have two manifolds, one stable and the other unstable, to generate heteroclinic chaos. Two numerical examples are given accordingly to the developed theory.