Home About us Contact
|
Home About us Contact | ||
|
|
||
Selective Breeding (selective + breeding)
Terms modified by Selective Breeding Selected AbstractsSelective breeding for the hybrid striped bass (Morone chrysops, Rafinesque ×M. saxatilis, Walbaum) industry: status and perspectivesAQUACULTURE RESEARCH, Issue 4 2006Amber F. Garber Abstract The hybrid striped bass (HSB) farming industry has considerable potential for growth into domestic retail markets, but expansion of this industry is limited by high production costs that dictate high prices for HSB. It is widely recognized within the industry that selective breeding of an improved HSB will be required to increase production efficiency and reduce market prices. A National Program of Genetic Improvement and Selective Breeding for the HSB Industry has been initiated and some progress has been made toward domestication of the parent species of the hybrid. However, uncertainty remains as to which breeding procedures will most rapidly yield sustainable genetic gains in key production traits. This paper consolidates and reviews general information on the biology of temperate basses (genus Morone) relevant to selective breeding of improved HSB. The topics covered include control of reproduction, geographic distribution of stocks and population genetic variation. This is followed by a brief review of the current application of selective breeding techniques, including those based on molecular markers. Finally, we discuss potential avenues for genetic improvement of HSB in a selective breeding program. [source] Effects of CRF1 -Receptor and Opioid-Receptor Antagonists on Dependence-Induced Increases in Alcohol Drinking by Alcohol-Preferring (P) RatsALCOHOLISM, Issue 9 2008Nicholas W. Gilpin Background:, Selective breeding of rats over generations and induction of alcohol dependence via chronic vapor inhalation both enhance alcohol consumption in animal models. The purpose of this study was to determine whether dependence-induced increases in alcohol consumption by P rats is sensitive to naltrexone, a general opioid receptor antagonist (but with highest affinity at the ,-opioid receptor at low doses), and the recently characterized small molecule CRF1 -receptor antagonist MPZP (N,N -bis(2-methoxyethyl)-3-(4-methoxy-2-methylphenyl)-2,5-dimethyl-pyrazolo[1,5- a]pyrimidin-7-amine). Methods:, P rats (n = 20) were trained to respond for alcohol and water in a 2-lever operant situation during daily 30-minute sessions. P rats were then matched for alcohol intake and exposed to chronic intermittent alcohol vapor (n = 10) or ambient air (n = 10) for approximately 10 weeks. All rats were then administered MPZP and naltrexone in 2 separate and consecutive Latin-square designs. Results:, MPZP attenuated dependence-induced increases in alcohol intake by P rats while having no effect on alcohol consumption by nondependent controls. Conversely, operant alcohol responding was reduced similarly in dependent and nondependent P rats by naltrexone. Conclusions:, These results confirm a role for brain CRF1 -receptor systems in dependence-induced changes in the reinforcing properties of alcohol, and CRF1 -receptor blockade appears to suppress dependence-induced drinking at lower doses in P rats relative to other rat lines. Therefore, brain CRF1 -receptor systems are important in the regulation of dependence-induced alcohol consumption, whereas brain opioid systems are important in the regulation of basal alcohol consumption by rats. [source] Selective breeding for the hybrid striped bass (Morone chrysops, Rafinesque ×M. saxatilis, Walbaum) industry: status and perspectivesAQUACULTURE RESEARCH, Issue 4 2006Amber F. Garber Abstract The hybrid striped bass (HSB) farming industry has considerable potential for growth into domestic retail markets, but expansion of this industry is limited by high production costs that dictate high prices for HSB. It is widely recognized within the industry that selective breeding of an improved HSB will be required to increase production efficiency and reduce market prices. A National Program of Genetic Improvement and Selective Breeding for the HSB Industry has been initiated and some progress has been made toward domestication of the parent species of the hybrid. However, uncertainty remains as to which breeding procedures will most rapidly yield sustainable genetic gains in key production traits. This paper consolidates and reviews general information on the biology of temperate basses (genus Morone) relevant to selective breeding of improved HSB. The topics covered include control of reproduction, geographic distribution of stocks and population genetic variation. This is followed by a brief review of the current application of selective breeding techniques, including those based on molecular markers. Finally, we discuss potential avenues for genetic improvement of HSB in a selective breeding program. [source] The effects of selective breeding for differential rates of 50-kHz ultrasonic vocalizations on emotional behavior in ratsDEVELOPMENTAL PSYCHOBIOLOGY, Issue 1 2009Jeffrey Burgdorf Abstract Fifty-kHz ultrasonic vocalizations have previously been shown to be positively correlated with reward and appetitive social behavior in rats, and to reflect a positive affective state. In this study, rats selectively bred for high and low rates of 50-kHz vocalizations as juveniles were tested as adults in a battery of behavioral tests for social/emotional behaviors. We found that animals selectively bred for high rates of 50-kHz vocalizations exhibited more crosses into the center area of the open field apparatus, were more likely to show a preference for a dilute sucrose solution (.8%) compared to tap water, and were less aggressive than randomly bred animals. Conversely, animals bred for low rates of 50-kHz calls produced more fecal boli during both open field testing and "tickling" stimulation, and made less contact with conspecifics in a social interaction test compared to randomly bred animals. We also observed that low line rats have elevated brain levels of cholecystokinin (CCK) in the cortex, which is consistent with literature showing that CCK content in the cortex is positively correlated with rates of aversive 22-kHz USVs. Conversely, high line animals had elevated levels of met-enkephalin in several brain regions, which is consistent with the role of endogenous-opioids in the generation 50-kHz USVs and positive affect. These results suggest that animals bred for high rates of 50-kHz may show a stress resilient phenotype, whereas low line rats may show a stress prone phenotype. As such these animals could provide novel insights into the neurobiology of emotion. © 2008 Wiley Periodicals, Inc. Dev Psychobiol 51: 34,46, 2009 [source] Growth curve analyses are best suited to examine the relation between developmental pathways and selective breeding: Comment on Hofer, Shair, Masmela, & Brunelli, "Developmental effects of selective breeding for an infantile trait: The rat pup ultrasonic isolation call"DEVELOPMENTAL PSYCHOBIOLOGY, Issue 4 2001George F. Michel Abstract Hofer, Brunelli, Shair, & Masmela (2001) provide valuable information about the effects of selective breeding on rat-pup behaviors and physiology. Although the design and statistical analytic techniques employed are typical of those used to evaluate behavioral development in animals, I offer several suggestions about how to evaluate the influence of selective breeding on developmental pathways using modern statistical techniques. As Hofer et al. demonstrate, the development of rat behavior and physiology can be an excellent model for examining the relation between selection and development. © 2001 John Wiley & Sons, Inc. Dev Psychobiol 39: 247,250, 2001 [source] Letter to the editor: Chronicle for an orphan trait: Comment on Hofer, Shair, Masmela, & Brunelli, "Developmental effects of selective breeding for an infantile trait: The rat pup ultrasonic isolation call"DEVELOPMENTAL PSYCHOBIOLOGY, Issue 4 2001Pierre L. Roubertoux Abstract Hofer, Brunelli, Shair, and Masmela (2001) examined several behavioral and physiological measures in low, high, and unselected lines obtained from a divergent selection for ultrasound production (USP) in young rats. Although the response to selection was clear-cut, few correlated responses appeared. This surprising result could be explained by two reasons. USP has polygenic correlates in this population, and most of the chromosomal regions that are linked with these measures only contribute to a small part of the genetic variance. Therefore, correlated responses to selection might exist, but the common genetic variance between the trait under selection and the indirectly selected trait is too small to be detected by a selective breeding strategy. © 2001 John Wiley & Sons, Inc. Dev Psychobiol 39: 251,254, 2001.. [source] REVIEW: The alcohol-preferring P rat and animal models of excessive alcohol drinkingADDICTION BIOLOGY, Issue 3-4 2006Richard L. Bell ABSTRACT The alcohol-preferring, P, rat was developed by selective breeding to study ethanol drinking behavior and its consequences. Characterization of this line indicates the P rat meets all of the criteria put forth for a valid animal model of alcoholism, and displays, relative to their alcohol-non-preferring, NP, counterparts, a number of phenotypic traits associated with alcohol abuse and alcoholism. Behaviorally, compared with NP rats, P rats are less sensitive to the sedative and aversive effects of ethanol and more sensitive to the stimulatory effects of ethanol. Neurochemically, research with the P line indicates the endogenous dopaminergic, serotonergic, GABAergic, opiodergic, and peptidergic systems may be involved in a predisposition for alcohol abuse and alcoholism. Paralleling the clinical literature, genetically selected P rats display levels of ethanol intake during adolescence comparable to that seen during adulthood. Binge drinking has been associated with an increased risk for health and other problems associated with ethanol abuse. A model of binge-like drinking during the dark cycle indicates that P rats will consume 6 g/kg/day of ethanol in as little as three 1-hour access periods/day, which approximates the 24-hour intake of P rats with free-choice access to a single concentration of ethanol. The alcohol deprivation effect (ADE) is a transient increase in ethanol intake above baseline values upon re-exposure to ethanol access after an extended period of deprivation. The ADE has been proposed to be an animal model of relapse behavior, with the adult P rat displaying a robust ADE after prolonged abstinence. Overall, these findings indicate that the P rat can be effectively used in models assessing alcohol-preference, a genetic predisposition for alcohol abuse and/or alcoholism, and excessive drinking using protocols of binge-like or relapse-like drinking. [source] Hormone response to bidirectional selection on social behaviorEVOLUTION AND DEVELOPMENT, Issue 5 2010Gro V. Amdam SUMMARY Behavior is a quantitative trait determined by multiple genes. Some of these genes may have effects from early development and onward by influencing hormonal systems that are active during different life-stages leading to complex associations, or suites, of traits. Honey bees (Apis mellifera) have been used extensively in experiments on the genetic and hormonal control of complex social behavior, but the relationships between their early developmental processes and adult behavioral variation are not well understood. Bidirectional selective breeding on social food-storage behavior produced two honey bee strains, each with several sublines, that differ in an associated suite of anatomical, physiological, and behavioral traits found in unselected wild type bees. Using these genotypes, we document strain-specific changes during larval, pupal, and early adult life-stages for the central insect hormones juvenile hormone (JH) and ecdysteroids. Strain differences correlate with variation in female reproductive anatomy (ovary size), which can be influenced by JH during development, and with secretion rates of ecdysteroid from the ovaries of adults. Ovary size was previously assigned to the suite of traits of honey bee food-storage behavior. Our findings support that bidirectional selection on honey bee social behavior acted on pleiotropic gene networks. These networks may bias a bee's adult phenotype by endocrine effects on early developmental processes that regulate variation in reproductive traits. [source] Physiological Society Symposium , the Athlete's HeartEXPERIMENTAL PHYSIOLOGY, Issue 5 2003Equine athletes, racing success, the equine athlete's heart Our recent data have confirmed that maximum oxygen delivery in racing Thoroughbreds is positively correlated to left ventricular mass measured by echocardiography. A similar, but weaker relationship also exists between left ventricular mass and Timeform performance rating in commercial racehorses. The relationship of the Thoroughbred heart to racing success and the special problems that selective breeding for aerobic capacity have had in this species are reviewed in this article. [source] Rats bred for high alcohol drinking are more sensitive to delayed and probabilistic outcomesGENES, BRAIN AND BEHAVIOR, Issue 7 2008C. J. Wilhelm Alcoholics and heavy drinkers score higher on measures of impulsivity than nonalcoholics and light drinkers. This may be because of factors that predate drug exposure (e.g. genetics). This study examined the role of genetics by comparing impulsivity measures in ethanol-naive rats selectively bred based on their high [high alcohol drinking (HAD)] or low [low alcohol drinking (LAD)] consumption of ethanol. Replicates 1 and 2 of the HAD and LAD rats, developed by the University of Indiana Alcohol Research Center, completed two different discounting tasks. Delay discounting examines sensitivity to rewards that are delayed in time and is commonly used to assess ,choice' impulsivity. Probability discounting examines sensitivity to the uncertain delivery of rewards and has been used to assess risk taking and risk assessment. High alcohol drinking rats discounted delayed and probabilistic rewards more steeply than LAD rats. Discount rates associated with probabilistic and delayed rewards were weakly correlated, while bias was strongly correlated with discount rate in both delay and probability discounting. The results suggest that selective breeding for high alcohol consumption selects for animals that are more sensitive to delayed and probabilistic outcomes. Sensitivity to delayed or probabilistic outcomes may be predictive of future drinking in genetically predisposed individuals. [source] QTL for traits related to humoral immune response estimated from data of a porcine F2 resource populationINTERNATIONAL JOURNAL OF IMMUNOGENETICS, Issue 3 2009K. Wimmers Summary This study aimed to map quantitative trait loci (QTL) for traits related to humoral innate immune defence. Therefore, haemolytic complement activity in the alternative and the classical pathway, serum concentration of C3c and of haptoglobin (HP) were measured in blood samples obtained from F2 piglets (n = 457) of a porcine F2 resource population before and after Mycoplasma hyopneumoniae, Aujeszky's disease virus (Suid herpesvirus I, SuHVI) and porcine reproductive and respiratory syndrome virus (PRRSV) vaccination at 6, 14 and 16 weeks of age. Animals were genotyped at 88 autosomal markers. QTL analysis was performed under the line cross and the half sib. Phenotypic data were adjusted for systematic effects by mixed models with and without repeated measures statement. In total, 46 and 21 estimated QTL positions were detected with genome-wide significance at the 0.05 and 0.01 level, respectively. The proximal region of SSC2 (orthologous to HSA11 0,70 Mb), the distal region of SSC4 (HSA1 95,155 Mb), and the intermediate region of SSC16 (HSA5 0,73 Mb and 150,174 Mb) showed a clustering of estimated QTL positions for complement activity based on the different models. A common genetic background, i.e. a single true QTL, might underlie these QTL positions for related traits. In addition, QTL for antibody titres were detected on SSC1, 2, 6 and 7. With regard to number and magnitude of their impact, QTL for humoral innate immune traits behave like those for other quantitative traits. Discovery of such QTL facilitates the identification of candidate genes for disease resistance and immune competence that are applicable in selective breeding and further research towards improving therapeutic and prophylactic measures. [source] Genetic quality of domesticated African tilapia populationsJOURNAL OF FISH BIOLOGY, Issue 2004R. E. Brummett Anecdotal and empirical evidence exists for substantial (up to 40%) declines in growth among Oreochromis populations domesticated in both large and small-scale fish farms in Africa. These declines are at least partly attributable to poor genetic management, including inadvertent selection, inbreeding, bottle-necks and founder effects. Due to restricted cash flow and investment capital, genetic management and selective breeding for the improvement of domesticate populations are difficult for small-scale farmers, but feasible on larger-scale farms. In managing domesticated gene pools, feral populations can serve as a broodstock reservoir, making the use of indigenous species advantageous. A development model of large-scale hatcheries producing selected lines of sex-reversed, indigenous tilapia for sale to smaller-scale farmers is proposed as a solution to the problems of poor genetic management in African aquaculture. [source] Differences in Growth and Nutrient Efficiency Between and Within Two Channel Catfish Ictalurus punctatus StrainsJOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 1 2005Brian. A 6-wk growth study was conducted comparing fingerling (mean weight = 24.7 g) USDA103 strain channel catfish Ictalurus punctatus to Norris strain channel catfish in an effort to determine strain differences in growth and nutrient efficiency. Variability within strains also was assessed by randomly selecting four families from each strain for comparison. On average, USDA103 fish gained significantly (P < 0.05) more weight (51.2 vs. 31.7 g) and length (4.7 vs. 4.1 cm) compared to Norris strain catfish. Significantly (P < 0.05) greater feed consumption (56.6 vs 41.3 g) and feed efficiency (95.7 vs. 89.9) for USDA103 catfish were also observed. Family differences in weight and length gain and feed intake were significant (P < 0.05) among USDA103 families; whereas, only differences in feed intake and feed efficiency were significant (P < 0.05) among Norris families. Nitrogen retention was higher (P < 0.05) for the Norris strain catfish (35.6%) relative to the USDA103 strain average (31.0%). The results of this study reiterate the superior growth and feed efficiency of the USDA103 strain of channel catfish. Observed differences among USDA103 families suggest that further improvements in weight gain can be made through selective breeding; however, improvements in feed and protein efficiency may be difficult. [source] Prevalence of Unilateral and Bilateral Deafness in Border Collies and Association with PhenotypeJOURNAL OF VETERINARY INTERNAL MEDICINE, Issue 6 2006Simon Platt Background:Congenital sensorineural deafness (CSD) occurs in Border Collies, but its prevalence and inheritance are unknown. This study estimated the prevalence of CSD in Border Collies and investigated its association with phenotypic attributes linked to the merle gene, including coat pigmentation and iris color. Hypothesis:Deafness in Border Collies is associated with pigmentation patterns linked to the merle gene. Animals:A total of 2597 Border Collies from the United Kingdom. Methods:A retrospective study of Border Collies tested, during 1994,2002, by using brainstem auditory evoked responses. Associations between deafness and phenotypic attributes were assessed by using generalized logistic regression. Results:The prevalence of CSD in puppies was estimated as 2.8%. The corresponding rates of unilateral and bilateral CSD were 2.3 and 0.5%, respectively. Adjustment for clustering of hearing status by litter reduced the overall prevalence estimate to 1.6%. There was no association between CSD and sex (P= .2). Deaf Border Collies had higher rates of merle coat pigmentation, blue iris pigment, and excess white on the head than normal hearing Border Collies (all P < .001). The odds of deafness were increased by a factor of 14 for Border Collies with deaf dams, relative to the odds for dogs with normal dams (P= .007), after adjustment for phenotypic attributes. Conclusions and Clinical Importance: Associations between CSD and pigmentation patterns linked to the merle gene were demonstrated for Border Collies. Evidence for an inherited component to CSD in Border Collies supports selective breeding from only tested and normal parents to reduce the prevalence of this disease. [source] Mutation Causing von Willebrand's Disease in Scottish TerriersJOURNAL OF VETERINARY INTERNAL MEDICINE, Issue 1 2000Patrick J. Venta Von Willebrand's Disease (vWD) in the Scottish Terrier breed is a serious, often fatal, hereditary bleeding disorder. Elimination of the mutated gene by selective breeding is an important goal for the health of this breed. Although the standard protein-based tests are accurate for identification of affected Scottish Terriers, they are not reliable for the identification of carriers of the mutant gene unless multiple replicate assays are performed. A simple, highly accurate test for carriers of the disease is needed so that veterinarians can counsel clients on which animals to use in their breeding programs. The complete coding region of von Willebrand factor (vWF) complementary DNA (cDNA) was sequenced from an affected animal, and a single base deletion in the codon for amino acid 85 of the prepro-vWF cDNA that leads to Scottish Terrier vWD was identified. A highly accurate polymerase chain reaction assay was developed that can distinguish homozygous normal animals from those that are homozygous affected or heterozygous. In a voluntary survey of 87 animals provided by Scottish Terrier owners, 15 were carriers and 4 were affected with vWD, 2 of which had previously been shown to have undetectable vWF. The determination of the complete canine vWF cDNA sequence should facilitate the identification of additional vWD alleles in other breeds and other species. [source] Isolation and characterization of 17 polymorphic microsatellites in grass carpMOLECULAR ECOLOGY RESOURCES, Issue 6 2007JIA LE LI Abstract Here we report the isolation and characterization of 17 polymorphic loci isolated from a partial genomic DNA library of grass carp (Ctenopharyngodon idellus) enriched for CA repeats. We tested variability of these microsatellites on 24 unrelated individuals collected in China. All microsatellites were polymorphic. The average allele number was 7.9 per locus, ranging from four to 13. The observed heterozygosity was from 0.46 to 0.88 with an average of 0.71, whereas the average expected heterozygosity was 0.78. Sixteen of the 17 microsatellites conformed to Hardy,Weinberg equilibrium, and inherited independently. These microsatellites can be used to study genetic diversity and population structure of wild populations, and facilitate selective breeding of cultured broodstocks. [source] Development and characterization of novel tetra-, tri-, and dinucleotide microsatellite markers in rainbow trout (Oncorhynchus mykiss)MOLECULAR ECOLOGY RESOURCES, Issue 2 2005I. B. SPIES Abstract We discuss the development and characterization of 40 polymorphic rainbow trout (Oncorhynchus mykiss) microsatellite loci. We used enriched libraries to isolate 14 dinucleotide, seven trinucleodide, eight compound di/tetranucleotide, and 11 tetranucleotide loci. These markers will be useful for selective breeding via marker-assisted selection, population genetics studies, parentage analysis, and have already been used for genome mapping. [source] Functional significance of genetic variation underlying limb bone diaphyseal structureAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 1 2010Ian J. Wallace Abstract Limb bone diaphyseal structure is frequently used to infer hominin activity levels from skeletal remains, an approach based on the well-documented ability of bone to adjust to its loading environment during life. However, diaphyseal structure is also determined in part by genetic factors. This study investigates the possibility that genetic variation underlying diaphyseal structure is influenced by the activity levels of ancestral populations and might also have functional significance in an evolutionary context. We adopted an experimental evolution approach and tested for differences in femoral diaphyseal structure in 1-week-old mice from a line that had been artificially selected (45 generations) for high voluntary wheel running and non-selected controls. As adults, selected mice are significantly more active on wheels and in home cages, and have thicker diaphyses. Structural differences at 1 week can be assumed to primarily reflect the effects of selective breeding rather than direct mechanical stimuli, given that the onset of locomotion in mice is shortly after Day 7. We hypothesized that if genetically determined diaphyseal structure reflects the activity patterns of members of a lineage, then selected animals will have relatively larger diaphyseal dimensions at 1 week compared to controls. The results provide strong support for this hypothesis and suggest that limb bone cross sections may not always only reflect the activity levels of particular fossil individuals, but also convey an evolutionary signal providing information about hominin activity in the past. Am J Phys Anthropol 143:21,30, 2010. © 2010 Wiley-Liss, Inc. [source] Modelling selective breeding in protandrous, batch-reared Asian sea bass (Lates calcarifer, Bloch) using walkback selectionAQUACULTURE RESEARCH, Issue 10 2010Nicholas Andrew Robinson Abstract A bioeconomic simulation model for Lates calcarifer predicted that a strategy involving crossing current generation males with previous generation females would be a practical, effective and profitable way of dealing with protandry when batch rearing for selective breeding to improve the growth rate. The strategy allowed earlier initialization and more frequent ongoing rounds of selection, and resulted in a 16,19% higher overall response, than an alternative where each generation's males were crossed with the same generation's females. The strategy also yielded the highest short-term benefit,cost ratio (13:1 versus 7:1 after 8 years of selective breeding) and the highest short- and long-term value for participants in a breeding cooperative (a net present value of AU$28 million and an internal rate of return of 144% over 10 years), due to higher yields per fixed costs of production per unit area and due to savings in feed costs per kilogram of production. Breeding facilities of scale producing 50 full-sibling families per generation were found to be more profitable than those producing 100 families. [source] Testing options for the commercialization of abalone selective breeding using bioeconomic simulation modellingAQUACULTURE RESEARCH, Issue 9 2010Nick Robinson Abstract The genetic response and economic benefit from alternative breeding programme designs for blacklip and greenlip abalone (Haliotis rubra and Haliotis laevigata, respectively) were evaluated using a computer simulation model. Two selection criteria were investigated, one used family breeding values for liability to disease challenge test infection and the other used a direct selection of the best performing individuals across families for growth rate. Five scales of breeding programme were tested and the model predicted that if growth rate is the only selection criterion, breeding programmes of a scale using 150 families of each species each generation would result in 12,13% genetic improvement in initial generations and have the greatest beneficial economic impact on the Australian abalone industry of the options tested. The model predicts an average discounted benefit,cost ratio of 48:1, total added discounted benefit of AU$4.90 for each kilogram of abalone produced and nominal economic effect on operating income of over AU$16 million per year after 10 years. If disease resistance is the only selective breeding criterion, 100 families of each species would result in the highest benefit,cost ratio of the options tested, although some genetic gain would need to be sacrificed to reduce inbreeding to acceptable levels in this scenario. A strategy for a stand-alone abalone selective breeding cooperative was also modelled. For a farm of current tank area yielding 100 t year,1, participation is expected to yield over AU$0.7 million in discounted total added production value and annual discounted returns of over AU$0.4 million per annum by year 10. [source] Production of a base population and its responses to F1 selection in the bay scallop, Argopecten irradians irradians Lamarck (1819)AQUACULTURE RESEARCH, Issue 9 2008Haibin Zhang Abstract A base population of the bay scallop, Argopecten irradians irradians Lamarck, was produced by crossing two cultured bay scallop populations. After 1 year of rearing, the top 10% truncation selection of the top 10% (i=1.755) was carried out in the base population of about 1300 adults. A control parental group with a an identical number to the select parental group was randomly selected from the entire population before isolation of the select parental group. The result showed that, at the larval stage, the growth rate of larvae in the selected line was significantly higher than that of the control (P<0.05), and that the genetic gain was 6.78%. Owing to the lower density of control at the spat stage, the mean shell length of the control line was larger than that of the select line at day 100. When the same density was adjusted between two lines in the grow-out stage (from day 100 to 160), the daily growth rate of the selected line was significantly higher than that of the control line (P<0.05). Survival of the select line was significantly larger than that of the control line in the grow-out stage. In conclusion, the results obtained from this experiment indicate that selective breeding from a base population with a high genetic diversity established by mass spawning between different populations appears to be a promising method of genetic improvement in bay scallop, A. irradians irradians Lamarck. [source] Realized heritability and response to selection for shell height in the pearl oyster Pinctada fucata (Gould)AQUACULTURE RESEARCH, Issue 8 2008Maoxian He Abstract The common pearl oyster, Pinctada fucata (Gould), is the most important species that is cultured for production of marine pearls in China. Heavy mortality and the decline of pearl quality have resulted in a breeding programme being established in recent years. In this study, we conducted selective breeding for the second generation of pearl oyster P. fucata (JCS-2) by mass selection for shell height (SH) with a selection intensity of 1.614, and analysed the growth of the selected line (JCS-2) and the non-selected control line (JCC) during a 1-year grow-out period. The results show that the selected line grew faster than the control one in the SH and total weight (TW) (P<0.05), and there were higher proportion of larger sized oysters. Coefficient of variation for SH of JCS-2 was smaller than that of JCC. The current genetic gains and realized heritability for JCS-2 averaged 16.03 ± 4.79% and 0.713 ± 0.208 at 3,15 months of age respectively. The findings indicated the selection response to faster growth for SH is markedly effective in the second generation, and there was a high correlated response of TW when selecting for SH. [source] Selective breeding for the hybrid striped bass (Morone chrysops, Rafinesque ×M. saxatilis, Walbaum) industry: status and perspectivesAQUACULTURE RESEARCH, Issue 4 2006Amber F. Garber Abstract The hybrid striped bass (HSB) farming industry has considerable potential for growth into domestic retail markets, but expansion of this industry is limited by high production costs that dictate high prices for HSB. It is widely recognized within the industry that selective breeding of an improved HSB will be required to increase production efficiency and reduce market prices. A National Program of Genetic Improvement and Selective Breeding for the HSB Industry has been initiated and some progress has been made toward domestication of the parent species of the hybrid. However, uncertainty remains as to which breeding procedures will most rapidly yield sustainable genetic gains in key production traits. This paper consolidates and reviews general information on the biology of temperate basses (genus Morone) relevant to selective breeding of improved HSB. The topics covered include control of reproduction, geographic distribution of stocks and population genetic variation. This is followed by a brief review of the current application of selective breeding techniques, including those based on molecular markers. Finally, we discuss potential avenues for genetic improvement of HSB in a selective breeding program. [source] Maternal variation in juvenile survival and growth of triploid hybrids between female rainbow trout and male brown trout and brook charrAQUACULTURE RESEARCH, Issue 2 2005J M Blanc Abstract Related sib-groups of rainbow trout × brown trout and rainbow trout × brook charr triploid hybrids and monospecific diploid and triploid rainbow trout controls were obtained from a common set of rainbow trout dams. On the basis of hybrid juvenile performances, 10 sib-groups were selected and the corresponding diploid rainbow trouts were raised up to adult stage. Females from each group of rainbow trout were used to produce a second generation of hybrid progeny, the performances of which were analysed for grandmaternal variation and relation with first-generation relatives. Results showed that hybrid traits (alevin yield and weight, survival and growth of fingerlings) were strongly influenced by maternal origin, and could be correlated to those of rainbow trout controls, but that maternal abilities had a low rate of inheritance. It was concluded that little improvement can be expected through selective breeding within parental populations. [source] Persea americana (avocado): bringing ancient flowers to fruit in the genomics eraBIOESSAYS, Issue 4 2008André S. Chanderbali The avocado (Persea americana) is a major crop commodity worldwide. Moreover, avocado, a paleopolyploid, is an evolutionary "outpost" among flowering plants, representing a basal lineage (the magnoliid clade) near the origin of the flowering plants themselves. Following centuries of selective breeding, avocado germplasm has been characterized at the level of microsatellite and RFLP markers. Nonetheless, little is known beyond these general diversity estimates, and much work remains to be done to develop avocado as a major subtropical-zone crop. Among the goals of avocado improvement are to develop varieties with fruit that will "store" better on the tree, show uniform ripening and have better post-harvest storage. Avocado transcriptome sequencing, genome mapping and partial genomic sequencing will represent a major step toward the goal of sequencing the entire avocado genome, which is expected to aid in improving avocado varieties and production, as well as understanding the evolution of flowers from non-flowering seed plants (gymnosperms). Additionally, continued evolutionary and other comparative studies of flower and fruit development in different avocado strains can be accomplished at the gene expression level, including in comparison with avocado relatives, and these should provide important insights into the genetic regulation of fruit development in basal angiosperms. BioEssays 30:386,396, 2008. © 2008 Wiley Periodicals, Inc. [source] | ||||||||||||||||