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Narrow-sense Heritabilities (narrow-sense + heritability)
Selected AbstractsSexual 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] Condition-dependent traits and the capture of genetic variance in male advertisement songJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 4 2004L. S. E. Brandt Abstract The occurrence of additive genetic variance (VA) for male sexual traits remains a major problem in evolutionary biology. Directional selection normally imposed by female choice is expected to reduce VA greatly, yet recent surveys indicate that a substantial amount remains in many species. We addressed this problem, also known as the ,lek paradox', in Achroia grisella (Lepidoptera: Pyralidae), an acoustic moth in which males advertise to females with a pulsed ultrasonic song. Using a standard half-sib/full-sib breeding design, we generated F1 progeny from whom we determined VA and genetic covariance (COVA) among seven traits: three song characters, an overall index of song attractiveness, nightly singing period, adult lifespan, and body mass at adult eclosion. Because A. grisella neither feed nor drink as adults, the last trait, eclosion body mass, is considered a measure of ,condition'. We found significant levels of VA and narrow-sense heritabilities (h2) for all seven traits and significant genetic correlations (= COVAi,j /,(VA i·VA j)) between most pairs of traits (i, j). Male attractiveness was positively correlated with body mass (condition), adult lifespan, and nightly singing period, which we interpret as an energy constraint preventing males in poor condition from singing attractively, from singing many hours per night, and from surviving an extended lifespan. The positive genetic correlation (r = 0.79) between condition and attractiveness, combined with significant levels of VA for both traits, indicates that much of the variation in male song can be explained by VA for condition. Finally, we discuss the morphological and physiological links between condition and song attractiveness, and the ultimate factors that may maintain VA for condition. [source] Genetic Analysis of the Latent Period of Stripe Rust in Wheat SeedlingsJOURNAL OF PHYTOPATHOLOGY, Issue 6 2004H. Dehghani Abstract Genetics of slow-rusting resistance to yellow rust (Puccinia striiformis f.sp. tritici) was studied by a half-diallel design using six wheat varieties, Tiritea (susceptible), Tancred, Kotare, Otane, Karamu, and Briscard. The parents and 15 F1 progenies were evaluated in the greenhouse by three pathotypes 7E18A,, 38E0A+, and 134E134A+. The latent period was measured as the number of days from inoculation to the appearance of the first pustule. For each pathotype a randomized complete block design was used and data were analysed by methods of Griffing and Hayman. The range of average degree of dominance was from complete dominance to over-dominance. Positive and negative degrees of dominance were observed for each pathotype that showed the reversal of dominance. Analysis of variance showed the importance of both additive and dominance effects in controlling the latent period. Broad-sense heritabilities were 0.99 and narrow-sense heritabilities ranged from 0.85 to 0.94. Briscard and Karamu for the pathotypes 38E0A+ and 134E134A+, Kotare for the pathotype 7E18A, and Tancred for the pathotype 38E0A+ had significant and positive general combining ability (GCA) (more resistance) for latent period. The crosses of Kotare with Tancred, Briscard and Karamu indicated the highest and positive specific combining ability (SCA) for the pathotype 7E18A,. Significant additive genetic component and moderate narrow-sense heritability indicate the possibility of improving for longer latent period of stripe rust in breeding programmes. [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] Genetic Analysis of the Latent Period of Stripe Rust in Wheat SeedlingsJOURNAL OF PHYTOPATHOLOGY, Issue 6 2004H. Dehghani Abstract Genetics of slow-rusting resistance to yellow rust (Puccinia striiformis f.sp. tritici) was studied by a half-diallel design using six wheat varieties, Tiritea (susceptible), Tancred, Kotare, Otane, Karamu, and Briscard. The parents and 15 F1 progenies were evaluated in the greenhouse by three pathotypes 7E18A,, 38E0A+, and 134E134A+. The latent period was measured as the number of days from inoculation to the appearance of the first pustule. For each pathotype a randomized complete block design was used and data were analysed by methods of Griffing and Hayman. The range of average degree of dominance was from complete dominance to over-dominance. Positive and negative degrees of dominance were observed for each pathotype that showed the reversal of dominance. Analysis of variance showed the importance of both additive and dominance effects in controlling the latent period. Broad-sense heritabilities were 0.99 and narrow-sense heritabilities ranged from 0.85 to 0.94. Briscard and Karamu for the pathotypes 38E0A+ and 134E134A+, Kotare for the pathotype 7E18A, and Tancred for the pathotype 38E0A+ had significant and positive general combining ability (GCA) (more resistance) for latent period. The crosses of Kotare with Tancred, Briscard and Karamu indicated the highest and positive specific combining ability (SCA) for the pathotype 7E18A,. Significant additive genetic component and moderate narrow-sense heritability indicate the possibility of improving for longer latent period of stripe rust in breeding programmes. [source] Heritability of morphophysiological traits and inbreeding effects in grazing-type lucernePLANT BREEDING, Issue 2 2005L. Pecetti Abstract To estimate heritability and inbreeding in grazing-type lucerne, 14 parent genotypes and their half-sib and selfed progeny were grown under spaced-plant conditions. Dry-matter weight (four cuts), plant height, basal plant diameter, stem density, and late-autumn vegetation were recorded on a plant basis. Genetic coefficients of variation for the three germplasm groups, and broad-sense heritability on a plot basis for parents were computed from variance component estimates; narrow-sense heritability was estimated from progeny-parent regression. Genetic variation was generally greater among selfed than half-sib progeny. Broad-sense heritability was high, while narrow-sense heritability was much lower for all traits except plant diameter. Inbreeding effects, assessed with comparison between parents and selfed progeny, were notable for plant weight and late-autumn vegetation only. The high correlation coefficients computed between parents and either progeny suggested the equivalent value of self- and polycross-progeny tests for selecting superior parents. [source] | ||||||||||