共查询到20条相似文献,搜索用时 31 毫秒
1.
Washington J. Gapare Miloš Ivković Brian S. Baltunis Colin A. Matheson Harry X. Wu 《Tree Genetics & Genomes》2010,6(1):113-125
Genetic variation for wood quality traits and diameter growth for radiata pine (Pinus radiata D. Don) at age 20/21 years was estimated from eight trials in Australia. The traits studied were wood density, acoustic time-of-flight
(an indirect measure of stiffness) and diameter at breast height (DBH). Wood density and DBH exhibited significant additive
genetic variation whereas non-additive effects were not significantly different from zero. Time of flight was also not significantly
different from zero for both additive and non-additive effects, respectively. Average single-site heritability estimates (±SE)
for wood density and DBH were 0.38 ± 0.10 and 0.16 ± 0.08, respectively. Pooled-site heritability estimates for wood density
and DBH were 0.38 ± 0.10 and 0.08 ± 0.10, respectively. For density, there was little evidence of genotype-by-environment
interaction (GEI) across the eight trials at the additive level (type B additive genetic correlation; r
BADD = 0.73 ± 0.08) and type B genetic correlation for full-sib families (r
BFS = 0.64 ± 0.08). In contrast, the type B additive genetic correlation for DBH was lower, (r
BADD = 0.51 ± 0.14), suggesting evidence of GEI. However, type B genetic correlation for full-sib families was moderate (0.63 ± 0.11)
for DBH, suggesting that there may be some stable full-sib families. On the basis of the results of this study, GEI should
be considered in order to optimise deployment of improved germplasm in Australia. 相似文献
2.
Relyea RA 《Journal of evolutionary biology》2005,18(4):856-866
The evolution of plastic traits requires phenotypic trade-offs and heritable traits, yet the latter requirement has received little attention, especially for predator-induced traits. Using a half-sib design, I examined the narrow-sense heritability of predator-induced behaviour, morphology, and life history in larval wood frogs (Rana sylvatica). Many of the traits had significant additive genetic variation in predator (caged Anax longipes) and no-predator environments. Whereas most traits had moderate to high heritability across environments, tail depth exhibited high heritability with predators but low heritability without predators. In addition, several traits had significant heritability for plasticity, suggesting a potential for selection to act on plasticity per se. Genetic correlations confirmed known phenotypic relationships across environments and identified novel relationships within each environment. This appears to be the first investigation of narrow-sense heritabilities for predator-induced traits and confirms that inducible traits previously shown to be under selection also have a genetic basis and should be capable of exhibiting evolutionary responses. 相似文献
3.
Matthew G. Hamilton Carolyn A. Raymond Chris E. Harwood Brad M. Potts 《Tree Genetics & Genomes》2009,5(2):307-316
Eucalyptus nitens plantations are generally established for pulpwood production but an increasing area is being managed for solid wood. Genetic
variation in, and correlations among, three Kraft pulpwood traits (diameter at breast height, basic density and near-infrared-predicted
cellulose content) and three 12-mm wood-core shrinkage traits (recoverable collapse, net shrinkage and gross shrinkage) were
examined, utilising data from two 9-year-old first-generation progeny trials in Tasmania. These trials contained approximately
400 open-pollinated families (over 100 of which were sampled for wood properties) representing three central-Victorian E. nitens races. Significant genetic variation at the race and/or within-race level was identified in all traits. Within races, relative
levels of additive genetic variation were higher for shrinkage traits, although narrow-sense heritabilities were lower and
the expression of genetic variation less stable across sites than for other wood property traits. Heterogeneous intertrait
genetic correlations were identified across sites between growth and some wood property traits. However, where significant,
genetic correlations indicated that within-race selection for growth would adversely affect core basic density and all core
shrinkage traits. Furthermore, results based on cores suggested that within-race selection for higher basic density would
favourably impact on cellulose content and collapse but selection for either higher basic density or cellulose content would
adversely affect net shrinkage. Most within-race genetic variation in gross shrinkage appeared to be due to genetic variation
in collapse. The implications of these results for sawn timber breeding will depend on the strength of genetic correlations
between core traits and rotation-age objective traits and objective trait economic weights. 相似文献
4.
Jose Alberto Ram��rez-Valiente Fernando Valladares Antonio Delgado Huertas S. Granados Ismael Aranda 《Tree Genetics & Genomes》2011,7(2):285-295
Increased drought severity is expected in the Mediterranean Basin over the twenty-first century, but our understanding of
the potential of most forest tree species to cope with it remains uncertain. In this study, (1) we examined the potential
effects of long-term selection and the capacity to respond to future changes in selective pressures in three populations of
cork oak (Quercus suber L.). For this purpose, we evaluated the response to dry conditions of 45 open-pollinated trees originating from populations
in Morocco, Portugal, and Spain. Growth, leaf size, specific leaf area (SLA), carbon isotope discrimination (Δ13C), leaf nitrogen content (Nmass), and total chlorophyll content (Chlmass) were measured in 9-year-old plants. (2) We also investigated the relationships between functional traits and aboveground
growth by regression models. Plants presenting larger and more sclerophyllous leaves (low SLA and high leaf thickness) exhibited
higher growths, with results suggesting that these traits are subjected to divergent selection in this species. Heritability
estimates were moderately high for Δ13C (0.43 ± 0.25–0.83 ± 0.31) and stem diameter (0.40 ± 0.15–0.71 ± 0.28) for the tree populations. For the rest of the traits
(except for annual growth), heritability values varied among populations, particularly for height, leaf size, leaf thickness,
and Nmass. Our results suggest that natural selection has led to local adaptations and has also affected the genetic variance intrapopulation
in these cork oak populations, although studies with a higher number of populations should be carried out across different
years. Additionally, the absence of significant genetic correlations and the fact that correlated traits did not undergo opposing
selection provided little evidence for constraints on evolution caused by genetic correlations. 相似文献
5.
Desmond J. Stackpole René E. Vaillancourt Marcelo de Aguigar Brad M. Potts 《Tree Genetics & Genomes》2010,6(2):179-193
Genetic parameters for stem diameter and wood density were compared at selection (4–5 years) and harvest (16–17 years) age
in an open-pollinated progeny trial of Eucalyptus globulus in Tasmania (Australia). The study examined 514 families collected from 17 subraces of E. globulus. Wood density was assessed on a subsample of trees indirectly using pilodyn penetration at both ages and directly by core
basic density at harvest age. Significant additive genetic variance and narrow-sense heritabilities (
h\textop2 h_{\text{op}}^2 ) were detected for all traits. Univariate and multivariate estimates of heritabilities were similar for each trait except
harvest-age diameter. Comparable univariate estimates of selection- and harvest-age heritabilities for diameter masked changes
in genetic architecture that occurred with stand development, whereby the loss of additive genetic variance through size-dependent
mortality was countered by the accentuation of additive genetic differences among survivors with age. Regardless, the additive
genetic (r
a) and subrace (r
s) correlations across ages were generally high for diameter (0.95 and 0.61, respectively) and pilodyn penetration (0.77 and
0.96), as were the correlations of harvest-age core basic density with selection- and harvest-age pilodyn (r
a −0.83, −0.88; r
s −0.96, −0.83). While r
s between diameter and pilodyn were close to zero at both ages, there was a significant change in r
a from adverse at selection age (0.25) to close to zero (−0.07) at harvest age. We argue that this change in the genetic correlation
reflects a decoupling of the genetic association of growth and wood density with age. This result highlights the need to validate
the use of selection-age genetic parameters for predicting harvest-age breeding values. 相似文献
6.
Guilherme Augusto Peres Silva Salvador Alejandro Gezan Melissa Pisaroglo de Carvalho Lígia Regina Lima Gouvêa Cecília Khusala Verardi André Luis Bombonato de Oliveira Paulo de Souza Gonçalves 《Tree Genetics & Genomes》2014,10(6):1511-1518
Rubber tree breeding programs are mainly driven by selection of individuals with high yield and quality of rubber. Data from 51 open-pollinated progenies tested on six sites in Brazil were analyzed over several traits to estimate the following: genetic parameters such as narrow-sense heritability and additive genetic variance in single- and multi-site analyses, type B correlations to determine the relevance of genotype-by-environment interactions and its effects on alternative selection strategies, additive genetic repeatability correlation for rubber yield based on three consecutive yearly measurements, and type A correlations to evaluate trait-to-trait genetic associations for all measured traits. Average rubber yield (RYm) showed an estimated narrow-sense heritability of 0.31, with an estimated type B correlation of 0.84, indicating low levels of genotype-by-environment interaction. The trait survival and number of latex vessel rings (RG) showed larger genotype-by-environment interaction and the lowest heritabilites. High to moderate type B correlation was found for most traits, with a value of 0.85 between diameter (or girth) and RYm; therefore, it is possible to achieve interesting rubber yield genetic gains (over 3 years of measurements) from indirect selection based on diameter at age 2. 相似文献
7.
Brian S. Baltunis Timothy A. Martin Dudley A. Huber John M. Davis 《Tree Genetics & Genomes》2008,4(4):797-807
Quantifying foliar stable carbon isotope discrimination (Δ) is a powerful approach for understanding genetic variation in
gas exchange traits in large populations. The genetic architecture of Δ and third-year height is described for more than 1,000
clones of Pinus taeda tested on two contrasting sites. for Δ was 0.14 (±0.03), 0.20 (±0.07), and 0.09 (±0.04) at Florida, Georgia, and across sites, respectively. for stable carbon isotope discrimination ranged from 0.25 (±0.03) at the Florida site to 0.33 (±0.03) at the Georgia site,
while the across-site estimate of was 0.19 (±0.02). For third-year height, ranged from 0.13 (±0.05) at the Georgia site to 0.20 (±0.06) at the Florida site with an across-site estimate of 0.09 (±0.05).
Broad-sense heritability estimates for third-year height were 0.23 (±0.03), 0.28 (±0.03), and 0.13 (±0.02) at the Florida
site, Georgia site, and across sites, respectively. Type B total genetic correlation for Δ was 0.70 ± 0.06, indicating that
clonal rankings were relatively stable across sites, while for third-year height, rankings of clones were more unstable across
the two trials . Third-year height and Δ were negatively correlated at the parental , full-sib family , and clonal levels, suggesting that genetic variation for Δ in P. taeda may be a result of differences in photosynthetic capacity. We conclude that Δ may be a useful selection trait to improve
water-use efficiency and for guiding deployment decisions in P. taeda. 相似文献
8.
Genetics of tassel branch number in maize and its implications for a selection program for small tassel size 总被引:2,自引:0,他引:2
Dr. S. H. Schuetz Dr. J. J. Mock 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1978,53(6):265-271
Summary Tassel branch numbers of six crosses of maize (Zea mays L.) were analyzed to determine inheritance of this trait. Generation mean analyses were used to estimate genetic effects, and additive and nonadditive components of variance were calculated and evaluated for bias due to linkage. Both narrow-sense and broad-sense heritabilities were estimated. Additive genetic variance estimates were significant in five of the six crosses, whereas estimates of variance due to nonadditive components were significant in only three crosses. Additionally, estimates of additive variance components usually were larger than corresponding nonadditive components. There was no evidence for linkage bias in these estimates. Estimates of additive genetic effects were significant in four of six crosses, but significant dominance, additive × additive and additive × dominance effects also were detected. Additive, dominance, and epistatic gene action, therefore, all influenced the inheritance of tassel branch number, but additive gene action was most important. Both narrow-sense and broadsense heritability estimates were larger than those reported for other physiological traits of maize and corroborated conclusions concerning the importance of additive gene action inferred from analyses of genetic effects and variances. We concluded that selection for smalltasseled inbreds could be accomplished most easily through a mass-selection and/or pedigree-selection system. Production of a small-tasseled hybrid would require crossing of two small-tasseled inbreds. We proposed two genetic models to explain unexpected results obtained for two crosses. One model involved five interacting loci and the other employed two loci displaying only additive and additive × additive gene action.Journal Paper No. J-9231 of the Iowa Agriculture and Home Economics Experiment Station, Ames, Iowa 50011. Project No. 2152 相似文献
9.
Washington J. Gapare Milo? Ivkovi? Gregory W. Dutkowski David J. Spencer Peter Buxton Harry X. Wu 《Tree Genetics & Genomes》2012,8(2):391-407
Growth and form traits data were obtained from eight provenance trials of radiata pine (Pinus radiata D. Don) planted across the radiata pine plantation estate in southeast Australia. The genetic pool included 466 open-pollinated
families collected from A?o Nuevo, Monterey and Cambria provenances on the Californian mainland coast in the USA and from
Guadalupe and Cedros islands off the coast of Baja California in Mexico. Early survival of all provenances was around 90%,
except for Cedros (<60%). Monterey and A?o Nuevo were the best performers at almost all sites. However, good growth performance
of Cambria and good stem straightness of Guadalupe on some sites are important results, because the genetic base of the present
Australian plantations evidently originated from only Monterey and A?o Nuevo. The average estimated single-site heritability
for diameter at breast height was 0.22 and 0.32 at juvenile and mature ages, respectively. Heritability estimates for stem
straightness and branching ranged from 0.23 to 0.55. Genetic correlation estimates between diameter at breast height (DBH)
at juvenile and rotation ages were all >0.80. Estimates of between-site genetic and provenance correlations for DBH were often
low, indicating high genotype by environment interaction across trials, consistent with previous Australian studies. However,
there was minimal G × E among trials on high-altitude high-rainfall sites and among trials on low-altitude, low-rainfall sites. 相似文献
10.
W. Patrick Cumbie Fikret Isik Bailian Li Barry Goldfarb 《Tree Genetics & Genomes》2011,7(6):1147-1158
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. 相似文献
11.
Heritability of life span in mice and its implication for direct and indirect selection for longevity 总被引:1,自引:0,他引:1
S. Klebanov K. Flurkey T.H. Roderick J.R. Archer M.C. Astle J. Chen D.E. Harrison 《Genetica》2000,110(3):209-218
We found high narrow-sense heritability of life span based on the regression of offspring on average parental (midparent)
life spans. In two mouse populations prepared using the 4-way-cross design, mean ± SE heritabilities were 62 ± 11% (P ≤ 0.001) and 44 ± 15% (P ≤ 0.01). To reflect inherited rates of aging, rather than resistance to early disease, data from the first 25% to die were
deleted, so that only about 40% of families were used for offspring-midparent regressions. Heritabilities still remained high,
38% and 55%, for the same two populations, respectively. Populations studied in two other experiments did not show nearly
as high heritabilities; in one case probably due to environmental stress, and in the other probably because the strains used
did not have sufficient additive variance in genes regulating longevity. Significant heritabilities occurred only when a wild
derived inbred strain was included in the 4-way cross. The age when a female ceased to reproduce appeared to be related to
the life spans of her offspring, but only weakly, not approaching significance for any individual experiment. The age when
a female became infertile was related to her life span, but the relationship disappeared when short-lived mice were excluded
from the analysis. Our findings indicate that, in sufficiently diverse mouse populations, selection for increased longevity
should be possible and that the direct selection for parental life span will be a more efficient strategy than selection for
female reproductive life span.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
12.
Heidi S. Dungey John H. Russell João Costa e Silva Charlie B. Low Mark A. Miller Kane R. Fleet Graham T. Stovold 《Tree Genetics & Genomes》2013,9(2):443-453
Two trials on Mexican cypress Cupressus lusitanica Miller in the North Island of New Zealand were assessed for diameter at breast height and at one site, subjective scores for branch size and stem canker (caused by Seiridium spp.) at age 6 from planting. The trials comprised 15 open-pollinated families, represented by both cloned and seedling progeny. Linear mixed model methodology, using a spatial model for the residuals, was applied to estimate genetic parameters. Estimated narrow-sense heritabilities were moderate to high for diameter at breast height (range from 0.46 to 0.62), stem canker (≈0.30) and branch size (range from 0.23 to 0.45) and did not appear to differ significantly between propagule types for all traits. Clonally replicated progeny led to an increase in accuracy of selection for additive genetic merit when compared with seedling testing, with the improvement being greater for traits with lower narrow-sense heritabilities. Estimated additive genetic correlations between cloned and seedling progeny were moderate to high (≥0.65) for diameter and branch size, indicating that selection decisions would not be substantially changed using either propagule type for progeny testing. All estimates of non-additive genetic variation based on the cloned progeny were non-significant. The use of spatial analysis was effective for diameter and branch size, but not for stem canker. No significant genotype by environment interaction was detected for diameter. Implications of the results for breeding and deployment of C. lusitanica are discussed. 相似文献
13.
Washington J. Gapare Brian S. Baltunis Milo? Ivkovi? Charlie B. Low Paul Jefferson Harry X. Wu 《Tree Genetics & Genomes》2011,7(2):409-419
Growth and form traits from a series of three provenance trials of Pinus radiata D. Don planted in New Zealand and Australia were analysed at age 9 years from planting. The trials included selections from
three mainland California natural populations—A?o Nuevo, Monterey and Cambria. Monterey and Cambria performed better than
A?o Nuevo at two New Zealand sites, but Monterey and A?o Nuevo were almost identical in growth, whereas Cambria grew less
vigorously at the Australian site. We detected significant provenance differences for diameter at breast height (DBH) growth
and stem straightness across countries (p < 0.001). Estimated heritability for DBH ranged from 0.19 to 0.26 within sites, while heritability estimates for stem straightness
and branching frequency ranged from 0.10 to 0.24. Estimated type B genetic correlations for DBH were always higher between
the two trials in New Zealand trials than between pairs of trials in New Zealand and the Australian site. The genetic coefficient
of variation (CVA) for DBH was around 8–10% compared to ca. 5% for the current breeding population. These results suggested that there is appreciable
genetic variation in the native populations, and infusion of these materials would increase the genetic variation in current
breeding populations. Ten unrelated parents ranked above control seedlots from the older open-pollinated seed orchard stock
for DBH growth and would be potential candidates for infusion. The promising performance of the Cambria material is an important
result because the genetic base of the present Australian and New Zealand plantations is principally derived from A?o Nuevo
and Monterey. 相似文献
14.
Maria João Gaspar Ana I. de-Lucas Ricardo Alía Jorge Almiro Pinto Paiva Elena Hidalgo José Louzada Helena Almeida Santiago C. González-Martínez 《Tree Genetics & Genomes》2009,5(4):609-616
The management of a genetic improvement program is based on the knowledge of the genetic parameters and their relationships
to determine the genetic gains. Knowledge of the coefficient of coancestry (θ) is a requirement for efficient progeny testing scheme and for estimating additive variance components for any quantitative
trait. When using open-pollinated families, most authors assume that the seedlings are related as half-sibs, but this is not
always true. Our aim was to estimate a mean value of the coancestry coefficient of the families present in a maritime pine
Pinus pinaster Ait. (maritime or cluster pine) progeny trial originating from seed collected in a clonal seed orchard and to study how deviations
from the standard assumption of θ = 0.125 affect heritability estimations. Five highly polymorphic microsatellite markers were scored in 125 offspring from
a subsample of five families from the progeny trial. The mean value of the coancestry coefficient of the families present
in this progeny trial was 0.130. Differences between the unadjusted and adjusted heritability estimates were more pronounced
in wood density (0.609 and 0.586, respectively) than in diameter (0.166 and 0.154, respectively). We conclude that in the
trial, the associated error in heritability estimates due to the inclusion of full-sibs, when assuming a standard coefficient
of relationship among open-pollinated sibs of 0.250, was low and that this result is robust with respect to the number of
families sampled, given unbiased estimates of average relationship among offspring within sib families. 相似文献
15.
S. Mucha F. Tortereau A. Doeschl-Wilson R. Rupp J. Conington 《Animal : an international journal of animal bioscience》2022,16(3):100456
Genetic selection focused purely on production traits has proven very successful in improving the productive performance of livestock. However, heightened environmental and infectious disease challenges have raised the need to also improve the resilience of animals to such external stressors, as well as their efficiency in utilising available resources. A better understanding of the relationship between efficiency and production and health traits is needed to properly account for it in breeding programmes and to produce animals that can maintain high production performance in a range of environmental conditions with minimal environmental footprint. The aim of this study was to perform a meta-analysis of genetic parameters for production, efficiency and health traits in sheep and goats. The dataset comprised 963 estimates of heritability and 572 genetic correlations collated from 162 published studies. A threelevel meta-analysis model was fitted. Pooled heritability estimates for milk production traits ranged between 0.27 ± 0.03 and 0.48 ± 0.13 in dairy goats and between 0.21 ± 0.06 and 0.33 ± 0.07 in dairy sheep. In meat sheep, the heritability of efficiency traits ranged from 0.09 ± 0.02 (prolificacy) up to 0.32 ± 0.14 (residual feed intake). For health traits, pooled heritability was 0.07 ± 0.01 (faecal egg count) and 0.21 ± 0.01 (somatic cell score) in dairy goats and 0.14 ± 0.04 (faecal egg count) and 0.13 ± 0.02 (somatic cell score) in dairy sheep. In meat sheep, the heritability of disease resistance and survival traits ranged between 0.07 ± 0.02 (mastitis) and 0.50 ± 0.10 (breech strike). Pooled estimates of genetic correlations between resilience and efficiency traits in dairy goats were not significantly different from zero with the exception of somatic cell score and fat content (?0.19 ± 0.01). In dairy sheep, only the unfavourable genetic correlation between somatic cell score and protein content (0.12 ± 0.03) was statistically significant. In meat sheep only, the correlations between growth and faecal egg count (?0.28 ± 0.11) as well as between growth and dagginess (?0.33 ± 0.13) were statistically significant and favourable. Results of this meta-analysis provide evidence of genetic antagonism between production and health in dairy sheep and goats. This was not observed in meat sheep where most of the pooled estimates had high standard errors and were non-significant. Based on the obtained results, it seems feasible to simultaneously improve efficiency and health in addition to production by including the different types of traits in the breeding goal. However, a better understanding of potential trade-offs between these traits would be beneficial. Particularly, more studies focused on reproduction and resilience traits linked to the animal’s multi-trait response to challenges are required. 相似文献
16.
Genetic parameters for growth, stem straightness, pilodyn penetration, relative bark thickness and survival were estimated in a base-population of five open-pollinated provenance/progeny trials of Eucalyptus viminalis. The trials, located in northern, central and southern Buenos Aires Province, Argentina, comprised 148 open-pollinated families from 13 Australian native provenances and eight local Argentinean seedlots. The Australian native provenances come from a limited range of the natural distribution. Overall survival, based on the latest assessment of each trial, was 62.4%. Single-site analyses showed that statistically significant provenances differences (p?<?0.05) for at least one of the studied traits in three out of the five trials analyzed. The local land race performed inconsistently in this study. The average narrow-sense individual-tree heritability estimate $ \left( {{{\hat{h}}^2}} \right) $ was 0.27 for diameter and 0.17 for total height. Values of $ {\hat{h}^2} $ also increased with age. Pilodyn penetration, assessed at only one site, was more heritable $ \left( {{{\hat{h}}^2} = 0.32} \right) $ than the average of growth traits. Estimated individual-tree heritabilities were moderate to low for stem straightness (average of 0.20) and relative bark thickness (0.16). The estimated additive genetic correlations $ \left( {{{{r}}_{{A}}}} \right) $ between diameter and height were consistently high and positive ( $ {{r}_{^A}} $ average of 0.90). High additive genetic correlations were observed between growth variables and pilodyn penetration ( $ {{r}_{^A}} $ average of 0.58). Relative bark thickness showed a negative correlation with diameter $ \left( {{{{r}}_{^A}} = - 0.39} \right) $ and height $ \left( {{{{r}}_{^A}} = - 0.51} \right) $ . The average estimated additive genetic correlation between sites was high for diameter (0.67). The implications of all these parameter estimates for genetic improvement of E. viminalis in Argentina are discussed. 相似文献
17.
The heritability estimates of 25 external morphometric characters and 23 craniometric indices are obtained by use of variances
in monoclonal all-female triploids and bisexual tetraploids of spined loaches (genus Cobitis, Cobitidae) collected from the same breeding biotope. Most of studied traits demonstrate low heritability confirming previous
conclusion on the similarity between external morphometric characters and craniological indices in relative effects of genetic
and environmental components in their total phenotypic variation. Low heritability estimates in most of external morphological
traits correspond to their low diagnostic value in Cobitis species. As a whole, in spite of certain deviations, studies on clonal forms do not refute the concept on higher heritability
estimates in diagnostically significant traits in comparison with traits without diagnostic values in the same taxonomic group.
Low heritability in most morphometric traits more probably is resulted from their low additive genetic variation caused by
strong selection of evolutionary developed specific body shape in spined loaches, because strong selection should reduce the
genetic variance in body proportions to minimal size. Sex differences observed in heritability estimates should be interpreted
as a result of linkage of several additive genes controlling these traits to sex chromosomes. A few characters demonstrating
high heritability estimates up to 0.492–0.580 are of great interest for taxonomic and phylogenetic studies in genus Cobitis and related taxa. 相似文献
18.
The maintenance of variation in sexually selected traits is a puzzle that has received increasing attention in the past several decades. Traits that are related to fitness, such as life‐history or sexually selected traits, are expected to have low additive genetic variance (and hence, heritability) due to the rapid fixation of advantageous alleles. However, previous analyses have suggested that the heritabilities of sexually selected traits are on average higher than nonsexually selected traits. We show that the heritabilities of sexually selected traits are not significantly different from those of nonsexually selected traits overall or when separated into the three trait categories: behavioural, morphological and physiological. In contrast with previous findings, the heritability of preference is quite low (h2 = 0.25 ± 0.06) and is in the same range as life‐history traits. We distinguish preferred traits as a category of sexually selected traits and find that the heritability of the former is not significantly different than sexually selected traits overall (0.48 ± 0.04 vs. 0.46 ± 0.03). We test the hypothesis that the heritability of sexually selected traits is negatively correlated with the strength of sexual selection. As predicted, there is a significant negative correlation between the heritabilities of sexually selected traits and the strength of selection. This suggests that heritabilities do indeed decrease as sexual selection increases but sexual selection is not strong enough to cause heritabilities of sexually selected traits to deviate from the same type of nonsexually selected traits. 相似文献
19.
Heritability of the backtest response in piglets and its genetic correlations with production traits
《Animal : an international journal of animal bioscience》2017,11(4):556-563
The backtest response of a pig gives an indication of its coping style, that is, its preferred strategy to cope with stressful situations, which may in turn be related to production traits. The objective of this study was therefore to estimate the heritability of the backtest response and estimate genetic correlations with production traits (birth weight, growth, fat depth and loin depth). The backtest was performed by placing the piglet on its back for 60 s and the number of struggles (NrS) and vocalizations (NrV), and the latency to struggle and vocalize (LV) was recorded. In total, 992 piglets were subjected to the backtest. Heritability estimates for backtest traits were statistically moderate (although high for behavioral traits), with LV having the highest heritability estimate (0.56±0.10, P<0.001) and NrS having the lowest estimate (0.37±0.09, P<0.001). Backtest traits also had high genetic correlations with each other, with vocalization traits (NrV and LV) having the highest (−0.94±0.03, P<0.001), and NrS with NrV the lowest correlation (0.70±0.09, P<0.001). No significant correlations were found between backtest traits and production traits, but correlations between NrS and birth weight (−0.38±0.25), and NrV and loin depth (−0.28±0.19) approached significance (P=0.07). More research into genotype-by-environment interactions may be needed to assess possible connections between backtest traits and production traits, as this may depend on the circumstances (environment, experiences, etc.). In conclusion, heritability estimates of backtest traits are high and it would therefore be possible to select for them. The high genetic correlations between backtest traits indicate that it may be possible to only consider one or two traits for characterization and selection purposes. There were no significant genetic correlations found between backtest traits and production traits, although some of the correlations approached significance and hence warrant further research. 相似文献
20.
Zhi-Qiang Chen María Rosario García Gil Bo Karlsson Sven-Olof Lundqvist Lars Olsson Harry X. Wu 《Tree Genetics & Genomes》2014,10(5):1291-1303
Unfavorable genetic correlations between growth and wood quality traits are one of the biggest challenges in advanced conifer breeding programs. To examine and deal with such correlation, increment cores were sampled at breast height from 5,618 trees in 524 open-pollinated families in two 21-year-old Norway spruce progeny trials in southern Sweden, and age trends of genetic variation, genetic correlation, and efficiency of selection were investigated. Wood quality traits were measured on 12-mm increment cores using SilviScan. Heritability was moderate (~0.4–0.5) for wood density and modulus of elasticity (MOE) but low (~0.2) for microfibril angle (MFA). Different age trends were observed for wood density, MFA, and MOE, and the lower heritability of MFA relative to wood density and MOE in Norway spruce contrasted with general trends of the three wood quality traits in pine. Genetic correlations among growth, wood density, MFA, and MOE increased to a considerably high value from pith to bark with unfavorable genetic correlations (?0.6 between growth and wood density, ?0.74 between growth and MOE). Age–age genetic correlations reached 0.9 after ring 4 for diameter at breast height (DBH), wood density, MFA, and MOE traits. Early selections at ring 10 for diameter and at ring 6 or 7 for wood quality traits had similar effectiveness as selection conducted at reference ring 15. Selection based on diameter alone produced 19.0 % genetic gain in diameter but resulted in 4.8 % decrease in wood density, 9.4 % decrease in MOE, and 8.0 % increase in MFA. Index selection with a restriction of no change in wood density, MOE, and MFA, respectively, produced relatively lower genetic gains in diameter (16.4, 12.2, and 14.1 %, respectively), indicating such index selection could be implemented to maintain current wood density. Index selection using economic weights is, however, recommended for maximum economic efficiency. 相似文献