Heritability of flight distance for Cydia pomonella

Cydia pomonella L. (Lepidoptera: Tortricidae) is considered to be rather sedentary, but some individuals undertake flights of several kilometres in the field. This paper investigates the genetic influence on this variability. The flight capacity was measured in the laboratory by a flight mill and its heritability was estimated for two different strains. The laboratory strain was kept for more than 45 generations and the field strain from Embrach (northern Switzerland) was recently collected in the field.The multiple-trait-restricted-maximum-likelihood method was used for the estimation of genetic variances and covariances. A mixed full-sib/half-sib design was applied for the field strain and a full-sib design for the laboratory strain. The heritability of total distance was 0.57 for the field strain and 0.37 for the laboratory strain (both sexes). In addition, a heritability of 0.38 for total distance was estimated by parent-offspring regression for the laboratory strain. All three values were significantly different from zero P<0.05 and show that there is a significant additive genetic influence on flight capacity.The genetic correlations between total distance and other flight traits (total duration, flight velocity, longest flight) were between 0.84 and 1.00 for both strains and suggest that these traits actually belong to a single one. High genetic correlations were also found between total distance and the morphological traits body weight and wing length for the field strain, whereas a negative correlation was found between total flight distance and body weight for the laboratory strain. This difference between the two strains was interpreted as a possible trade-off between flight capacity and fecundity.     

Genetic parameters of dermal patterns of ridge counts.

Dermatoglyphic traits including ridge counts and pattern type counts on fingers were studied in 711 families representing six racial groups in Hawaii. Heritability tesimates were derived from regressions of offspring on father, mother and mid-parent values as well as from full-sib correlations. These estimates varied from 0.23 for radial loops to 0.80 for total ridge count. The heritability estimates were lower for ridge counts of single hands or single digits.     

Effects of propagule type on genetic parameters of wood density and growth in a loblolly pine progeny test at ages 10 and 11?years

Nine full-sib families of loblolly pine (Pinus taeda L.) were produced by a 3 × 3 factorial mating design. Rooted cuttings and seedlings of full-sib families were tested together in two field locations. Twelve-millimeter wood increment cores were collected from 10- and 11-year-old test trees. On each of the two sites, there were six blocks and a split-plot design, with propagule type as the whole plot and family as the sub-plot. In addition to the collection of wood samples, height and diameter of 1,600 trees were measured. No significant differences were found between cuttings and seedlings for wood density and growth traits. Significant family variation was found for growth and wood density. Genetic parameters estimated for wood density and growth traits using seedlings and rooted cuttings showed that individual-tree and family heritability estimates from rooted cuttings were similar to or higher than those from seedlings for all traits. Half-sib breeding values for parents were highly correlated based on seedling and rooted cutting estimates for height (0.95) and wood density (0.99) but not for diameter (0.56), which suggests that wood density and height breeding value estimates from rooted cuttings in clonal progeny tests can be estimated by traditional seedling tests, but not for tree diameter.     

GENETIC AND SOCIAL INHERITANCE OF BODY AND EGG SIZE IN THE BARNACLE GOOSE (BRANTA LEUCOPSIS)

We present heritability estimates for final size of body traits and egg size as well as phenotypic and genetic correlations between body and egg traits in a recently established population of the barnacle goose (Branta leucopsis) in the Baltic area. Body traits as well as egg size were heritable and, hence, could respond evolutionarily to phenotypic selection. Genetic correlations between body size traits were significantly positive and of similar magnitude or higher than the corresponding phenotypic correlations. Heritability estimates for tarsus length obtained from full-sib analyses were higher than those obtained from midoffspring-midparent regressions, and this indicates common environment effects on siblings. Heritabilities for tarsus length obtained from midoffspring-mother regressions were significantly higher than estimates from midoffspring-father regressions. The results suggest that this discrepancy is not caused by maternal effects through egg size, nor by extra-pair fertilizations, but by a socially inherited foraging site fidelity in females.     

The common quantitative genetic basis of wing morphology and diapause occurrence in the cricket Gryllus veletis

A covariation between wing morphology and diapause occurrence has been observed in many insect species, but the genetic basis of this covariation has never been established. This study measures the heritability of, and genetic correlation between, these two ecologically important threshold traits in the cricket Gryllus veletis. A total of 81 full-sib families were reared in the laboratory to estimate these parameters. A comparison of laboratory and field samples showed that these two traits are highly plastic. The heritability of wing morphology was 0.25 (0.09), the heritability of diapause occurrence was 0.77 (0.11) and the genetic correlation between them was 0.61 (0.19). These estimates did not differ between males and females. The significance of these quantitative genetic parameters is discussed with reference to the monomorphism of natural populations of G. veletis for diapause occurrence and with reference to the trade-off between the ability to disperse by flight and the ability to diapause found in at least one closely related species. A survey of the literature reveals that genetic correlations between diapause occurrence or wing morphology and various other traits are common in insects, suggesting that these two traits are often genetically integrated in insect life-histories.     

Additive and non-additive genetic parameters for multipurpose traits in a clonally replicated incomplete factorial test of <Emphasis Type="Italic">Castanea</Emphasis> spp.

Second-year traits of growth, stem form, terminal flushing, and survival were assessed in 1770 ramets from 295 clones of 16 full-sib families of Castanea spp. Additive, dominance, and epistatic genetic variances were estimated in a clonally replicated incomplete 5?×?4 factorial test. Parents of the mating design were selected mainly on their phenotypes for wood quality (Castanea sativa traditional varieties) and their proven resistance to Phytophthora spp. (Asiatic species and Castanea crenata?×?C. sativa hybrids). Additive genetic variances were estimated to be 1.7–9 times greater than the dominance components. Inferred epistatic variance components showed a significant role in controlling growth traits and branch length. Narrow- and broad-sense heritability estimates showed that terminal flushing date was the most heritable trait, followed by height. The high estimates of half-sib, full-sib, and clonal mean heritabilities for almost all traits suggest that different strategies of backwards and forwards selection could be proposed. The ranking of the breeding values of parents allow us to select the best parents for new crosses and extend the mating design. Favorable genetic correlations were found between growth traits and straightness, so multi-trait selection looks promising. Our results provide the first information on the partitioning of genetic variance in Castanea spp. and a starting point for devising new selection strategies.     

Ultrastructural features of chloride cells in the gill epithelium of the Atlantic salmon, Salmo salar, and their modifications during smoltification

To elucidate the ultrastructural modifications of the gill epithelium during smoltification, gills of the Atlantic salmon (Salmo salar) were examined by electron microscopy at three stages of this process, which were defined as follows: "parrs" were freshwater fish that had not yet started their transformation; "freshwater smolts" were freshwater fish that were ready to enter seawater; and "seawater smolts" were smolts that had been transferred from fresh water and maintained for 4 days in seawater (35%). In the gill epithelium of parrs, there were two types of chloride cells. The large chloride cells contained deeply stained mitochondria and numerous apical, irregular, dense, membrane-bound bodies that formed 77% of the chloride cell population and were distinguished easily from small chloride cells that have distinctly paler mitochondria and no dense bodies in their apical cytoplasm. In freshwater smolts, the large chloride cells formed 95% of the chloride-cell population. In contrast to the small chloride cells that were not modified, they almost doubled in size. Their tubular system developed extensively to form a tight network with regular meshes significantly smaller than those observed in parr chloride cells. Forty percent of the large chloride cells were associated with a new type of cell, the accessory cell, to which they were bound by shallow apical junctions. Half of these accessory cells were not seen to be in contact with the external medium. In seawater smolts, 80% of the large chloride cells were associated with accessory cells. Most accessory cells reached the external medium and sent numerous cytoplasmic interdigitations within the apical portion of the adjacent chloride cells. As a result, a section through the apical portion of the chloride cells and their associated accessory cells revealed a mosaic of interlocked cell processes bound together by an extended, shallow apical junction. It was concluded that the Atlantic salmon develops in fresh water most of the ultrastructural modifications of the gill epithelium which in most euryhaline fish are triggered by exposure to seawater. The effective transfer into seawater would act only as a final stimulus to achieve some adequacy between the freshwater smolt and its new environment.     

Genetic parameters and response to selection for growth in tambaqui

Although the tambaqui (Colossoma macropomum) is the most cultivated native fish species in Brazil, estimated breeding values for growth traits are rarely used for selection of superior individuals in commercial fingerling production. This study aimed to estimate the (co)variance components of growth traits. Body weight, length and width of 2500 tambaqui were determined at tagging and at 6 and 12 months after tagging in a commercial breeding programme in Brazil. Heritability estimates were low for traits measured at tagging (0.10 to 0.19) and moderate to high for traits measured at 6 and 12 months (0.23 to 0.81). Common full-sib effects were high at tagging (>73%), low at 6 months and negligible at 12 months. Positive genetic correlations were found among growth traits at 12 months (0.84 to 0.99) and between growth traits at 6 and 12 months (0.80 to 0.92). These results show that animal selection can be performed at 6 months after tagging. Expected genetic gains for growth traits ranged from 8% to 31%. A simulation of the sex ratio was performed, as individuals did not reach sexual maturity during the experimental period. Because of the sexual dimorphism, more accurate heritability estimates were obtained when considering the female proportion to be 90% in the high-weight group. The findings indicate that it is possible to obtain considerable genetic gains in growth by selecting for growth traits. The development of a tool to determine the sex of animals at early stages can improve the response to selection in tambaqui.     

A QTL study of cattle behavioral traits in embryo transfer families.

Two behavioral traits, temperament and habituation, were measured in 130 calves from 17 full-sib families which comprise the Canadian Beef Cattle Reference Herd. Using variance components, heritability was calculated as 0.36 for temperament and 0.46 for habituation. Genotyping of 162 microsatellites at approximately 20 cM intervals allowed the detection of six quantitative trait loci (QTL) for behavior traits on cattle chromosomes 1, 5, 9, 11, 14, 15.     

Changes in carbonic anhydrase activity in coho salmon smolts resulting from physical training and transfer into seawater

Carbonic anhydrase (CA) activity was measured in blood and in gill tissue of coho salmon smolts during chronic exercise and subsequent transfer into seawater. The mean level of CA activity was higher in blood than gill tissue in both freshwater and seawater. CA activity in gill tissue increased significantly after the smolts had adapted to seawater. CA activity in blood decreased significantly in the group of fish given the highest exercise level after they had adapted to seawater. There were no significant differences in CA activity in gill tissue between control and exercise groups in either freshwater or seawater.     

Genetic parameters for growth, wood density and pulp yield in Eucalyptus globulus

Genetic variation and co-variation among the key pulpwood selection traits for Eucalyptus globulus were estimated for a range of sites in Portugal, with the aim of improving genetic parameters used to predict breeding values and correlated response to selection. The trials comprised clonally replicated full-sib families (eight trials) and unrelated clones (17 trials), and exhibited varying levels of pedigree connectivity. The traits studied were stem diameter at breast height, Pilodyn penetration (an indirect measure of wood basic density) and near infrared reflectance predicted pulp yield. Univariate and multivariate linear mixed models were fitted within and across sites, and estimates of additive genetic, total genetic, environmental and phenotypic variances and covariances were obtained. All traits studied exhibited significant levels of additive genetic variation. The average estimated within-site narrow-sense heritability was 0.19 ± 0.03 for diameter and 0.29 ± 0.03 for Pilodyn penetration, and the pooled estimate for predicted pulp yield was 0.42 ± 0.14. When they could be tested, dominance and epistatic effects were generally not statistically significant, although broad-sense heritability estimates were slightly higher than narrow-sense heritability estimates. Averaged across trials, positive additive (0.64 ± 0.08), total genetic (0.58 ± 0.04), environmental (0.38 ± 0.03) and phenotypic (0.43 ± 0.02) correlation estimates were consistently obtained between diameter and Pilodyn penetration. This data argues for at least some form of pleiotropic relationship between these two traits and that selection for fast growth will adversely affect wood density in this population. Estimates of the across-site genetic correlations for diameter and Pilodyn penetration were high, indicating that the genotype by environment interaction is low across the range of sites tested. This result supports the use of single aggregated selection criteria for growth and wood density across planting environments in Portugal, as opposed to having to select for performance in different environments.     

壳白长牡蛎家系幼体生长存活比较及生长性状遗传参数评估

研究以经过连续7代人工选育壳白长牡蛎品系为素材, 通过巢式设计, 成功构建了12个半同胞家系和29个全同胞家系, 同时以未经选育的个体子代为对照组, 评估了各家系和对照组幼体在不同日龄下的生长和存活差异。结果显示, 不同日龄, 壳白长牡蛎家系幼体生长和存活率均高于对照组, 壳高和存活率分别提高3.65%—14.58%和1.11%—19.26%; 生长和存活性状在不同壳白家系间差异显著(P<0.05), 其中G11、G15和G35家系在生长和存活率方面均有较大优势, 在19日龄, 与壳白家系平均值相比, 其壳高的累积生长量分别增加11.87%、17.03%和30.32%, 存活率分别提高38.35%、33.41%和51.07%; 与对照组相比, 其壳高的累积生长量分别增加34.09%、28.18%和49.31%, 存活率分别提高65.00%、59.11%和80.18%。同时对壳白长牡蛎幼体壳高和壳长的遗传参数进行了评估。壳白长牡蛎幼体壳高和壳长的遗传力变化范围分别为0.28—0.81、0.42—0.88, 均属于中高遗传力; 壳白长牡蛎幼体不同日龄壳高和壳长的遗传相关和表型相关均为正相关, 相关系数的范围分别为0.35—0.81、0.57—0.85。研究为培育生长性能优良和存活率高的壳白长牡蛎品系提供了基础资料。     

Heritability estimates from genomewide relatedness matrices in wild populations: Application to a passerine,using a small sample size

Genomic developments have empowered the investigation of heritability in wild populations directly from genomewide relatedness matrices (GRM). Such GRM‐based approaches can in particular be used to improve or substitute approaches based on social pedigree (PED‐social). However, measuring heritability from GRM in the wild has not been widely applied yet, especially using small samples and in nonmodel species. Here, we estimated heritability for four quantitative traits (tarsus length, wing length, bill length and body mass), using PED‐social, a pedigree corrected by genetic data (PED‐corrected) and a GRM from a small sample (n = 494) of blue tits from natural populations in Corsica genotyped at nearly 50,000 filtered SNPs derived from RAD‐seq. We also measured genetic correlations among traits, and we performed chromosome partitioning. Heritability estimates were slightly higher when using GRM compared to PED‐social, and PED‐corrected yielded intermediate values, suggesting a minor underestimation of heritability in PED‐social due to incorrect pedigree links, including extra‐pair paternity, and to lower information content than the GRM. Genetic correlations among traits were similar between PED‐social and GRM but credible intervals were very large in both cases, suggesting a lack of power for this small data set. Although a positive linear relationship was found between the number of genes per chromosome and the chromosome heritability for tarsus length, chromosome partitioning similarly showed a lack of power for the three other traits. We discuss the usefulness and limitations of the quantitative genetic inferences based on genomic data in small samples from wild populations.     

Temperature and genotypic effects on life history and fluctuating asymmetry in a field strain of Culex pipiens

Fluctuating asymmetry (FA) has been proposed as a tool to measure levels of stress experienced by populations of organisms during development. To be of value as a bio-marker to highlight conditions at particular sites, it is important that variation in FA is due to environmental (eg pollution) variation and not genetic variation among populations and families, in other words heritability for FA should be very close to zero. A full-sib design was set up in which families of Culex pipiens mosquitoes collected from the field were reared at three different developmental temperatures. The effects of temperature and family on developmental rate, egg to adult survival and four wing morphological measures were assessed. There was both a temperature and a family effect on development rate and survival. Temperature affected all four wing traits, but an influence of family was only evident in two of the wing traits. Two separate measures of FA for each of the wing traits were obtained. The mean estimates of FA were mainly around 1% of the value of the character measured. There was evidence of an increase in FA with increase in temperature stress. Heritability was estimated for the wing traits and wing trait FA's using restricted estimation maximum likelihood. The estimates of heritability for the wing traits were small and, individually, did not differ significantly from zero. There was also no evidence of heritable genetic variation for any of the wing trait FA's. The results are discussed in relation to other studies where FA heritabilities have been estimated and in relation to the use of FA as an indicator of environmental stress.     

Estimates of Heritability for Growth and Shell Color Traits and Their Genetic Correlations in the Black Shell Strain of Pacific Oyster <Emphasis Type="Italic">Crassostrea gigas</Emphasis>

The Pacific oyster Crassostrea gigas has been introduced widely and massively and became an economically important aquaculture species on a global scale. We estimated heritabilities of growth and shell color traits and their genetic correlations in black shell strain of C. gigas. Analyses were performed on 22 full-sib families in a nested mating design including 410 individuals at harvest (24 months of age). The parentage assignment was inferred based on four panels of multiplex PCR markers including 10 microsatellite loci and 94.9% of the offspring were unambiguously assigned to single parent pairs. The Spearman correlation test (r = ? 0.992, P < 0.001) demonstrated the high consistency of the shell pigmentation (SP) and L* and their same efficacy in shell color measurements. The narrow-sense heritability estimated under the animal model analysis was 0.18 ± 0.12 for shell height, 0.25 ± 0.16 for shell length, 0.10 ± 0.09 for shell width, 0.42 ± 0.20 for total weight, 0.32 ± 0.18 for shell weight, and 0.68 ± 0.16 for L*, 0.69 ± 0.16 for shell pigmentation, respectively. The considerable additive genetic variation in growth and shell color traits will make it feasible to produce genetic improvements for these traits in selective breeding program. High genetic and phenotypic correlations were found among growth traits and among shell color traits. To optimize a selection strategy for both fast growth and pure dark shell strain of C. gigas, it is proposed to take both total weight and black shell as joint objective traits in selective breeding program. Our study offers an important reference in the process of selective breeding in black shell color stain of C. gigas and will facilitate to develop favorable breeding strategies of genetic improvements for this economically important strain.     

Genetic and environmental correlation and path coefficient analysis of fruit yield per bush and other traits in black currants (Ribes nigrum L.)

Twenty-five F1 hybrid families of black currants (Ribes nigrum L.) originating from diallel crosses of five cultivars were assessed. Phenotypic correlation coefficient between full-sib family means (rFS), genetic correlation coefficient between full-sib family expected values (rG) and the environmental correlation were estimated on the basis of two years of observations for 12 quantitative characteristics studied. Evident repeatability of correlations in both years was proved. A considerable consistency between the values of genetic and phenotypic correlation coefficients was also observed. Coefficients of phenotypic and environmental correlation were significant for many pairs of traits. Most of the significant environmental correlation coefficients were found for the same pairs of characteristics for which phenotypic correlation coefficients were significant. This shows that genetic and environmental factors affected similar traits. Fruit yield expressed the largest number of significant correlations with other traits. Path coefficient analysis indicated that plant and berry size were the main factors influencing directly fruit yield in both years. It was proved that the number and length of one-year-old shoots via bush size had very large indirect effects on fruit yield per plant.     

A multi-marker test based on family data in genome-wide association study

Background

Requirements for successful implementation of multivariate animal threshold models including phenotypic and genotypic information are not known yet. Here simulated horse data were used to investigate the properties of multivariate estimators of genetic parameters for categorical, continuous and molecular genetic data in the context of important radiological health traits using mixed linear-threshold animal models via Gibbs sampling. The simulated pedigree comprised 7 generations and 40000 animals per generation. Additive genetic values, residuals and fixed effects for one continuous trait and liabilities of four binary traits were simulated, resembling situations encountered in the Warmblood horse. Quantitative trait locus (QTL) effects and genetic marker information were simulated for one of the liabilities. Different scenarios with respect to recombination rate between genetic markers and QTL and polymorphism information content of genetic markers were studied. For each scenario ten replicates were sampled from the simulated population, and within each replicate six different datasets differing in number and distribution of animals with trait records and availability of genetic marker information were generated. (Co)Variance components were estimated using a Bayesian mixed linear-threshold animal model via Gibbs sampling. Residual variances were fixed to zero and a proper prior was used for the genetic covariance matrix.

Results

Effective sample sizes (ESS) and biases of genetic parameters differed significantly between datasets. Bias of heritability estimates was -6% to +6% for the continuous trait, -6% to +10% for the binary traits of moderate heritability, and -21% to +25% for the binary traits of low heritability. Additive genetic correlations were mostly underestimated between the continuous trait and binary traits of low heritability, under- or overestimated between the continuous trait and binary traits of moderate heritability, and overestimated between two binary traits. Use of trait information on two subsequent generations of animals increased ESS and reduced bias of parameter estimates more than mere increase of the number of informative animals from one generation. Consideration of genotype information as a fixed effect in the model resulted in overestimation of polygenic heritability of the QTL trait, but increased accuracy of estimated additive genetic correlations of the QTL trait.

Conclusion

Combined use of phenotype and genotype information on parents and offspring will help to identify agonistic and antagonistic genetic correlations between traits of interests, facilitating design of effective multiple trait selection schemes.     

Bayesian inference of genetic parameters for ultrasound scanning traits of Kivircik lambs

Ultrasound scanning traits have been adapted in selection programs in many countries to improve carcass traits for lean meat production. As the genetic parameters of the traits interested are important for breeding programs, the estimation of these parameters was aimed at the present investigation. The estimated parameters were direct and maternal heritability as well as genetic correlations between the studied traits. The traits were backfat thickness (BFT), skin+backfat thickness (SBFT), eye muscle depth (MD) and live weights at the day of scanning (LW). The breed investigated was Kivircik, which has a high quality of meat. Six different multi-trait animal models were fitted to determine the most suitable model for the data using Bayesian approach. Based on deviance information criterion, a model that includes direct additive genetic effects, maternal additive genetic effects, direct maternal genetic covariance and maternal permanent environmental effects revealed to be the most appropriate for the data, and therefore, inferences were built on the results of that model. The direct heritability estimates for BFT, SBFT, MD and LW were 0.26, 0.26, 0.23 and 0.09, whereas the maternal heritability estimates were 0.27, 0.27, 0.24 and 0.20, respectively. Negative genetic correlations were obtained between direct and maternal effects for BFT, SBFT and MD. Both direct and maternal genetic correlations between traits were favorable, whereas BFT–MD and SBFT–MD had negligible direct genetic correlation. The highest direct and maternal genetic correlations were between BFT and SBFT (0.39) and between MD and LW (0.48), respectively. Our results, in general, indicated that maternal effects should be accounted for in estimation of genetic parameters of ultrasound scanning traits in Kivircik lambs, and SBFT can be used as a selection criterion to improve BFT.     

Selection bias in quantitative trait loci mapping

A simulation study was performed to see whether selection affected quantitative trait loci (QTL) mapping. Populations under random selection, under selection among full-sib families, and under selection within a full-sib family were simulated each with heritability of 0.3, 0.5, and 0.7. They were analyzed with the marker spacing of 10 cM and 20 cM. The accuracy for QTL detection decreased for the populations under selection within full-sib family. Estimates of QTL effects and positions differed (P < .05) from their input values. The problems could be ignored when mapping a QTL for the populations under selection among full-sib families. A large heritability helped reduction of such problems. When the animals were selected within a full-sib family, the QTL was detected for the populations with heritability of 0.5 or larger using the marker spacing of 10 cM, and with heritability of 0.7 using the marker spacing of 20 cM. This study implied that when selection was introduced, the accuracy for QTL detection decreased and the estimates of QTL effects were biased. A caution was warranted on the decision of data (including selected animals to be genotyped) for QTL mapping.     

Length–weight relationships for 37 freshwater fish species of Iran

Length–weight parameters were estimated for 37 freshwater fish species of Iran belonging to seven families. Significant length–weight relationships with high correlation coefficients were found for all species.