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Significant Heritability (significant + heritability)
Selected AbstractsGenetic and environmental effects on morphology and fluctuating asymmetry in nestling barn swallowsJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 3 2000Cadée A barn swallow Hirundo rustica partial cross-fostering experiment with simultaneous brood size manipulation was conducted in two years with contrasting weather conditions, to estimate heritable variation in tarsus, tail and wing size and fluctuating asymmetry. Environmental stress had contrasting effects depending on trait type. Significant heritabilities for tarsus, tail and wing size were found only in enlarged broods irrespective of year effects, while tarsus asymmetry was significantly heritable in the year with benign weather conditions irrespective of brood size manipulation effects. Tail, wing and composite (multicharacter) asymmetry were never significantly heritable. The environment with the higher heritability generally had higher additive genetic variance and lower environmental variance, irrespective of trait type. Heritability was larger for trait size than for trait asymmetry. Patterns of genetic variation in nestlings do not necessarily translate to the juvenile or adult stage, as indicated by lack of correlation between nestling and fledgling traits. [source] Genetic variation in the life-history traits of Epiphyas postvittana: population structure and local adaptationAUSTRAL ECOLOGY, Issue 4 2000Hainan Gu Abstract The light brown apple moth, Epiphyas postvittana (Walker) shows high intraspecific variability in morphological, physiological, demographic and behavioural characters. To gain insight into the extent of adaptation and evolutionary changes in response to environmental heterogeneity in this species, quantitative genetic analyses of life-history variation were conducted for two natural populations under two thermal conditions (23°C and 28°C). Paternal half-sib heritability and genetic correlation in six life-history traits (i.e. development time, adult body weight, adult lifespan, age at first reproduction, the number of eggs laid during the first 5 days after emergence, and total fecundity) were compared. Significant heritabilities were shown consistently in development time; this is also true for adult body weight, except for the Canberra population at 23°C. However, neither population differences nor the effect of temperature were statistically detectable for any of these heritabilities, confirming the genetically determined flexibility. Positive genetic correlations between development time and adult body weight, and negative genetic correlations between the number of eggs laid during the first 5 days and adult lifespan were present for these populations at both temperatures, indicating the presence of genetic constraints. Pairwise comparisons of genetic correlations revealed the heterogeneity of the two populations and across temperatures. These results suggest that the structure of genetic covariance might have changed significantly during the divergence of natural populations and in response to the alteration of environmental conditions in E. postvittana. [source] Genetic variation in the life-history traits of Epiphyas postvittana: population structure and local adaptationAUSTRAL ECOLOGY, Issue 4 2000HAINAN GU Abstract The light brown apple moth, Epiphyas postvittana (Walker) shows high intraspecific variability in morphological, physiological, demographic and behavioural characters. To gain insight into the extent of adaptation and evolutionary changes in response to environmental heterogeneity in this species, quantitative genetic analyses of life-history variation were conducted for two natural populations under two thermal conditions (23°C and 28°C). Paternal half-sib heritability and genetic correlation in six life-history traits (i.e. development time, adult body weight, adult lifespan, age at first reproduction, the number of eggs laid during the first 5 days after emergence, and total fecundity) were compared. Significant heritabilities were shown consistently in development time; this is also true for adult body weight, except for the Canberra population at 23°C. However, neither population differences nor the effect of temperature were statistically detectable for any of these heritabilities, confirming the genetically determined flexibility. Positive genetic correlations between development time and adult body weight, and negative genetic correlations between the number of eggs laid during the first 5 days and adult lifespan were present for these populations at both temperatures, indicating the presence of genetic constraints. Pairwise comparisons of genetic correlations revealed the heterogeneity of the two populations and across temperatures. These results suggest that the structure of genetic covariance might have changed significantly during the divergence of natural populations and in response to the alteration of environmental conditions in E. postvittana. [source] Heritability of life-history tactics and genetic correlation with body size in a natural population of brook charr (Salvelinus fontinalis)JOURNAL OF EVOLUTIONARY BIOLOGY, Issue 6 2007V. THÉRIAULT Abstract A common dimorphism in life-history tactic in salmonids is the presence of an anadromous pathway involving a migration to sea followed by a freshwater reproduction, along with an entirely freshwater resident tactic. Although common, the genetic and environmental influence on the adoption of a particular life-history tactic has rarely been studied under natural conditions. Here, we used sibship-reconstruction based on microsatellite data and an ,animal model' approach to estimate the additive genetic basis of the life-history tactic adopted (anadromy vs. residency) in a natural population of brook charr, Salvelinus fontinalis. We also assess its genetic correlation with phenotypic correlated traits, body size and body shape. Significant heritability was observed for life-history tactic (varying from 0.52 to 0.56 depending on the pedigree scenario adopted) as well as for body size (from 0.44 to 0.50). There was also a significant genetic correlation between these two traits, whereby anadromous fish were genetically associated with bigger size at age 1 (rG = ,0.52 and ,0.61). Our findings thus indicate that life-history tactics in this population have the potential to evolve in response to selection acting on the tactic itself or indirectly via selection on body size. This study is one of the very few to have successfully used sibship-reconstruction to estimate quantitative genetic parameters under wild conditions. [source] SEXUAL DIMORPHISM IN RELATION TO CURRENT SELECTION IN THE HOUSE FINCHEVOLUTION, Issue 3 2000Alexander V. Badyaev Abstract., Sexual dimorphism is thought to have evolved in response to selection pressures that differ between males and females. Our aim in this study was to determine the role of current net selection in shaping and maintaining contemporary sexual dimorphism in a recently established population of the house finch (Carpodacus mexicanus) in Montana. We found strong differences between sexes in direction of selection on sexually dimorphic traits, significant heritabilities of these traits, and a close congruence between current selection and observed sexual dimorphism in Montana house finches. Strong directional selection on sexually dimorphic traits and similar intensities of selection in each sex suggested that sexual dimorphism arises from adaptive responses in males and females, with both sexes being far from their local fitness optimum. This pattern is expected when a recently established population experiences continuous immigration from ecologically distinct areas of a species range or as a result of widely fluctuating selection pressures, as found in our study. Strong and sexually dimorphic selection pressures on heritable morphological traits, in combination with low phenotypic and genetic covariation among these traits during growth, may have accounted for close congruence between current selection and observed sexual dimorphism in the house finch. This conclusion is consistent with the profound adaptive population divergence in sexual dimorphism that accompanied very successful colonization of most of the North America by the house finch over the last 50 years. [source] The genetic basis of early-life morphological traits and their relation to alternative male reproductive tactics in Atlantic salmonJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 4 2010D. J. PáEZ Abstract Although heritability estimates for traits potentially under natural selection are increasingly being reported, their estimation remains a challenge if we are to understand the patterns of adaptive phenotypic change in nature. Given the potentially important role of selection on the early life phenotype, and thereby on future life history events in many fish species, we conducted a common garden experiment, using the Atlantic salmon (Salmo salar L.), with two major aims. The first objective is to determine how the site of origin, the paternal sexual tactic and additive genetic effects influence phenotypic variation of several morphological traits at hatching and emergence. The second aim is to test whether a link exists between phenotypic characteristics early in life and the incidence of male alternative tactics later in life. We found no evidence of a site or paternal effect on any morphological trait at hatching or emergence, suggesting that the spatial phenotypic differences observed in the natural river system from which these fish originated are mainly environmentally driven. However, we do find significant heritabilities and maternal effects for several traits, including body size. No direct evidence was found correlating the incidence of precocious maturation with early life characteristics. We suggest that under good growing conditions, body size and other traits at early developmental stages are not reliable cues for the surpassing of the threshold values associated with male sexual development. [source] Genetic parameters and QTL analysis of ,13C and ring width in maritime pinePLANT CELL & ENVIRONMENT, Issue 8 2002O. Brendel Abstract Classical quantitative genetics and quantitative trait dissection analysis (QTL) approaches were used in order to investigate the genetic determinism of wood cellulose carbon isotope composition (,13C, a time integrated estimate of water use efficiency) and of diameter growth and their relationship on adult trees (15 years) of a forest tree species (maritime pine). A half diallel experimental set-up was used to (1) estimate heritabilities for ,13C and ring width and (2) to decompose the phenotypic ,13C/growth correlation into its genetic and environmental components. Considerable variation was found for ,13C (range of over 3,) and for ring width (range of over 5 mm) and significant heritabilities (narrow sense 0·17/0·19 for ,13C and ring width, respectively, 100% additivity). The significant phenotypic correlation between ,13C and ring width was not determined by the genetic component, but was attributable to environmental components. Using a genetic linkage map of a full-sib family, four significant and four suggestive QTLs were detected for ,13C, the first for ,13C in a forest tree species, as far as known to the authors. Two significant and four suggestive QTLs were found for ring width. No co-location of QTLs was found between ,13C and growth. [source] CLIMATIC AND TEMPORAL EFFECTS ON THE EXPRESSION OF SECONDARY SEXUAL CHARACTERS: GENETIC AND ENVIRONMENTAL COMPONENTSEVOLUTION, Issue 3 2004Dany Garant Abstract Despite great interest in sexual selection, relatively little is known in detail about the genetic and environmental determinants of secondary sexual characters in natural populations. Such information is important for determining the way in which populations may respond to sexual selection. We report analyses of genetic and large-scale environmental components of phenotypic variation of two secondary sexual plumage characters (forehead and wing patch size) in the collared flycatcher Ficedula albicollis over a 22-year period. We found significant heritability for both characters but little genetic covariance between the two. We found a positive association between forehead patch size and a large-scale climatic index, the North Atlantic Oscillation (NAO) index, but not for wing patch. This pattern was observed in both cross-sectional and longitudinal data suggesting that the population response to NAO index can be explained as the result of phenotypic plasticity. Heritability of forehead patch size for old males, calculated under favorable conditions (NAO index median), was greater than that under unfavorable conditions (NAO index < median). These changes occurred because there were opposing changes in additive genetic variance (VA) and residual variance (VR) under favorable and unfavorable conditions, with VA increasing and VR decreasing in good environments. However, no such effect was detected for young birds, or for wing patch size in either age class. In addition to these environmental effects on both phenotypic and genetic variances, we found evidence for a significant decrease of forehead patch size over time in older birds. This change appears to be caused by a change in the sign of viability selection on forehead patch size, which is associated with a decline in the breeding value of multiple breeders. Our data thus reveal complex patterns of environmental influence on the expression of secondary sexual characters, which may have important implications for understanding selection and evolution of these characters. [source] Geographical range size heritability: what do neutral models with different modes of speciation predict?GLOBAL ECOLOGY, Issue 3 2007David Mouillot ABSTRACT Aim, Phylogenetic conservatism or heritability of the geographical range sizes of species (i.e. the tendency for closely related species to share similar range sizes) has been predicted to occur because of the strong phylogenetic conservatism of niche traits. However, the extent of such heritability in range size is disputed and the role of biology in shaping this attribute remains unclear. Here, we investigate the level of heritability of geographical range sizes that is generated from neutral models assuming no biological differences between species. Methods, We used three different neutral models, which differ in their speciation mode, to simulate the life-history of 250,000 individuals in a square lattice of 50 × 50 cells. These individuals can speciate, reproduce, migrate and die in the metacommunity according to stochastic events. We ran each model for 3000 steps and recorded the range size of each species at each step. The heritability of geographical range size was assessed using an asymmetry coefficient between range sizes of sister species and using the coefficient of correlation between the range sizes of ancestors and their descendants. Results, Our results demonstrated the ability of neutral models to mimic some important observed patterns in the heritability of geographical range size. Consistently, sister species exhibited higher asymmetry in range sizes than expected by chance, and correlations between the range sizes of ancestor,descendant species pairs, although often weak, were almost invariably positive. Main conclusions, Our findings suggest that, even without any biological trait differences, statistically significant heritability in the geographical range sizes of species can be found. This heritability is weaker than that observed in some empirical studies, but suggests that even here a substantial component of heritability may not necessarily be associated with niche conservatism. We also conclude that both present-day and fossil data sets may provide similar information on the heritability of the geographical range sizes of species, while the omission of rare species will tend to overestimate this heritability. [source] Sexual dimorphism and the genetic potential for evolution of sex allocation in the gynodioecious plant, Schiedea salicariaJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 1 2008A. K. SAKAI Abstract Sex allocation theory addresses how separate sexes can evolve from hermaphroditism but little is known about the genetic potential for shifts in sex allocation in flowering plants. We tested assumptions of this theory using the common currency of biomass and measurements of narrow-sense heritabilities and genetic correlations in Schiedea salicaria, a gynodioecious species under selection for greater differentiation of the sexes. Female (carpel) biomass showed heritable variation in both sexes. Male (stamen) biomass in hermaphrodites also had significant heritability, suggesting the potential for further evolution of dioecy. Significant positive genetic correlations between females and hermaphrodites in carpel mass may slow differentiation between the sexes. Within hermaphrodites, there were no negative genetic correlations between male and female biomass as assumed by models for the evolution of dioecy, suggesting that S. salicaria is capable of further changes in biomass allocation to male and female functions and evolution toward dioecy. [source] The heritability of inducible defenses in tadpolesJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 4 2005R. A. RELYEA Abstract 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. [source] Fluctuating asymmetry in a secondary sexual trait: no associations with individual fitness, environmental stress or inbreeding, and no heritabilityJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 1 2003L. E. B. Kruuk Abstract It has been suggested that fluctuating asymmetry (FA) in secondary sexual traits may be a useful indicator of either individual quality or environmental stress. We tested this concept using a series of analyses of FA in male antler size in a wild red deer (Cervus elaphus) population, using four measures of size repeated across successive years on the same individuals. We found no consistent evidence of correlations between traits in levels of FA, nor of any associations between known environmental or developmental conditions. None of the four measures of FA showed a significant heritability (average h2=0.041), nor was there any evidence of inbreeding depression. For three of the four traits, fluctuating asymmetry did not predict either annual or lifetime breeding success. However there were significant associations between breeding success and FA in antler length. Given the series of null results in our other tests, it seems likely that this was a direct mechanistic effect rather than because measures of FA were indicative of individual quality or condition. [source] Analysis of Heritability of Hormonal Responses to Alcohol in Twins: Beta-Endorphin as a Potential Biomarker of Genetic Risk for AlcoholismALCOHOLISM, Issue 3 2000J. C. Froehlich Background: Hormonal responses to alcohol have been reported to differ in subjects with and without a family history of alcoholism which suggests that alcohol-induced hormonal changes might be used to identify individuals who are at elevated genetic risk for developing alcoholism. However, before a biological response can be used as a marker of genetic risk for disease, it must first be demonstrated that the response is, in fact, heritable. The present study was designed to determine whether hormonal responses to alcohol are heritable. Methods: The adrenocorticotropic hormone (ACTH), beta-endorphin (,-E), cortisol (CORT), and prolactin (PRL) responses to alcohol were examined in male and female identical (monozygotic or MZ) and fraternal (dizygotic or DZ) twin pairs. Male subjects consumed 0.35g ethanol/kg body weight (BW) and female consumed 0.325 g ethanol/kg BW in each of two alcohol drinking sessions administered 1 hr apar (total dose of 0.7 g/kg BW in males and 0.65 g/kg BW in females). Plasma hormone content was analyzed in samples collected before (resting conditions) and at 15, 60, 75, 120, 180, and 240 min after onset of drinking. Hormonal responses to alcohol were examined with twin analyses using the TWINAN90 program. A separate analysis was performed for each of the four hormones. A subset of subjects from each zygosity was seen on two separate occasions to establish retest reliability. Heritability of hormonal responses to alcohol was estimated using the intraclass correlation approach before and after removing the contribution of covariates that have the potential of influencing the plasma levels of these hormones. Results: Resting plasma levels of all four hormones were within the expected range, and the ,-E, ACTH, and PRL responses to the alcohol challenge evidenced good test-retest reliability. Of the four hormones examined, the only one that showed significant heritability after alcohol drinking was ,-E. Heritability estimates were not altered for any of the four hormones after removal of the variance contributed by covariates, such as gender and age. Conclusions: Taken together with other recent findings, the results suggest that the ,-E response to alcohol may represent a new biomarker that can be used to identify individuals who are at elevated genetic risk for developing alcoholism. [source] Heritability of plasma concentrations of clotting factors and measures of a prethrombotic state in a protein C-deficient familyJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 2 2004C. Y. Vossen Summary.,Background:,Earlier studies found strong support for a genetic basis for regulation of coagulation factor levels and measures of a prethrombotic state (d -dimer, prothrombin fragment 1.2). Objectives:,Estimation of how much of the variation in the levels of coagulation factors and measures of a prethrombotic state, including measures of protein C activation and inactivation, could be attributed to heritability and household effect. Patients and methods:,Blood samples were collected from 330 members of a large kindred of French-Canadian origin with type I protein C deficiency. Heritability and common household effect were estimated for plasma concentrations of prothrombin, factor (F)V, factor VIII, factor (F)IX, fibrinogen, von Willebrand factor (VWF), antithrombin, protein C, protein S, protein Z, protein Z-dependent protease inhibitor (ZPI), fibrinopeptide A (FPA), protein C activation peptide (PCP), activated protein C,protein C inhibitor complex (APC,PCI), activated protein C,,1 -antitrypsin complex (APC,,1AT), prothrombin fragment 1.2 (F1.2) and d -dimer, using the variance component method in sequential oligo-genic linkage analysis routines (SOLAR). Results:,The highest heritability was found for measures of thrombin activity (PCP and FPA). High estimates were also found for prothrombin, FV, FIX, protein C, protein Z, ZPI, APC,PCI and APC,,1AT. An important influence of shared household effect on phenotypic variation was found for VWF, antithrombin, protein S and F1.2. Conclusions:,We found strong evidence for the heritability of single coagulation factors and measures of a prethrombotic state. Hemostatic markers with statistically significant heritability constitute potential targets for the identification of novel genes involved in the control of quantitative trait loci. [source] Genome-wide linkage analysis of quantitative biomarker traits of osteoarthritis in a large, multigenerational extended familyARTHRITIS & RHEUMATISM, Issue 3 2010Hsiang-Cheng Chen Objective The genetic contributions to the multifactorial disorder osteoarthritis (OA) have been increasingly recognized. The goal of the current study was to use OA-related biomarkers of severity and disease burden as quantitative traits to identify genetic susceptibility loci for OA. Methods In a large multigenerational extended family (n = 350), we measured 5 OA-related biomarkers: hyaluronan (HA), cartilage oligomeric matrix protein (COMP), N-propeptide of type IIA collagen (PIIANP), C-propeptide of type II procollagen (CPII), and type II collagen neoepitope (C2C). Single-nucleotide polymorphism markers (n = 6,090) covering the whole genome were genotyped using the Illumina HumanLinkage-12 BeadChip. Variance components analysis, as implemented in the Sequential Oligogenic Linkage Analysis Routines, was used to estimate heritabilities of the quantitative traits and to calculate 2-point and multipoint logarithm of odds (LOD) scores using a polygenic model. Results After adjusting for age and sex, we found that 4 of the 5 biomarkers exhibited significant heritability (PIIANP 0.57, HA 0.49, COMP 0.43, C2C 0.30; P , 0.01 for all). Fourteen of the 19 loci that had multipoint LOD scores of >1.5 were near to or overlapped with previously reported OA susceptibility loci. Four of these loci were identified by more than 1 biomarker. The maximum multipoint LOD scores for the heritable quantitative biomarker traits were 4.3 for PIIANP (chromosome 8p23.2), 3.2 for COMP (chromosome 8q11.1), 2.0 for HA (chromosome 6q16.3), and 2.0 for C2C (chromosome 5q31.2). Conclusion Herein, we report the first evidence of genetic susceptibility loci identified by OA-related biomarkers in an extended family. Our results demonstrate that serum concentrations of PIIANP, HA, COMP, and C2C have substantial heritable components, and using these biomarkers, several genetic loci potentially contributing to the genetic diversity of OA were identified. [source] | |||||||||||||