The variability of wood basic density and fibre length was determined in six 13-year-old willow clones growing under two different site conditions in Argentina. Values of basic density and wood fibre length were obtained and variance analyses were performed considering site and clone as sources of variation. Components of genetic and phenotypic variations were determined to calculate heritability in the broad sense. Site influence was significant for basic density, which ranged from 0.364 kg/dm3 and 0.455 kg/dm3. Clones “americano” and hybrid cv “A 13-44” showed the highest density values in both sites. For fibre length, values of the continental site were significantly higher. For each clone, mean values vary between 837.1 μm and 1142.1 μm. Heritability values show that the genetic control is stronger for density (h2 = 0.65) than for fibre length (h2 = 0.32). The clones “americano” and “13-44” stand out because of their high density and long fibres.
Silvia Monteoliva, Gabriela Senisterra and Raúl Marlats
Diane J. Austin-Broos
Argues that Jamaican notions of 'race' and 'class' can be rendered as a discourse of heritable biological and environmental identity. There has been a movement in the meaning of colour categories from an emphasis on biology, to a greater emphasis on environment. This transition has been encouraged by the emergence of class as a 20th-c. idiom.
Brian K. Via, Michael Stine, Todd F. Shupe, Chi-Leung So and Leslie Groom
Improvement of specific gravity through tree breeding was an early choice made in the mid 20th century due to its ease of measurement and impact on pulp yield and lumber strength and stiffness. This was often the first, and in many cases, the only wood quality trait selected for. However, from a product standpoint, increased specific gravity has shown to lower many paper strength and stiffness properties and has been assumed to be directly attributable to increased fiber coarseness. As a result, it is currently not clear which fiber trait would best benefit a tree improvement program for paper products. This review found coarseness to be perhaps more important to paper strength and stiffness whereas tracheid length showed better promise from a breeding point of view due to its independence from specific gravity. However, both traits possessed strong heritability and influence on product performance and thus both would be beneficial to breed for depending on organizational goals and end product mix. The objective of this paper is to review and prioritize coarseness and tracheid length from both an end use and raw material perspective. To aid in prioritization, the variation, correlation, and heritability of both traits were reviewed along with significant genetic and phenotypic correlations. Variation trends within and between families as well as within a tree were reviewed.
Maximilian J. Telford
Molecular cladistics is an emerging discipline in which any heritable molecular characteristic can be treated in the same way that a traditional cladist would treat a morphological character. Taxa that share specific derived molecular characters (synapomorphies)are recognized as more closely related to each other than they are to other taxa without these characters. Herein, I point out that molecular characters are susceptible to the same problems of homoplasy and uncertain polarity as morphological characters and illustrate these problems (and point towards a general solution) using examples from the Metazoa.
Microfibril angle (MFA) is perhaps the easiest ultrastructural variable to measure for wood cell walls, and certainly the only such variable that has been measured on a large scale. Because cellulose is crystalline, the MFA of the S2 layer can be measured by X-ray diffraction. Automated X-ray scanning devices such as SilviScan have produced large datasets for a range of timber species using increment core samples. In conifers, microfibril angles are large in the juvenile wood and small in the mature wood. MFA is larger at the base of the tree for a given ring number from the pith, and decreases with height, increasing slightly at the top tree. In hardwoods, similar patterns occur, but with much less variation and much smaller microfibril angles in juvenile wood. MFA has significant heritability, but is also influenced by environmental factors as shown by its increased values in compression wood, decreased values in tension wood and, often, increased values following nutrient or water supplementation. Adjacent individual tracheids can show moderate differences in MFA that may be related to tracheid length, but not to lumen diameter or cell wall thickness. While there has been strong interest in the MFA of the S2 layer, which dominates the axial stiffness properties of tracheids and fibres, there has been little attention given to the microfibril angles of S1 and S3 layers, which may influence collapse resistance and other lateral properties. Such investigations have been limited by the much greater difficulty of measuring angles for these wall layers. MFA, in combination with basic density, shows a strong relationship to longitudinal modulus of elasticity, and to longitudinal shrinkage, which are the main reasons for interest in this cell wall property in conifers. In hardwoods, MFA is of more interest in relation to growth stress and shrinkage behaviour.
Vincent Vedel and Wallace Arthur
(Lewis 1961), gene expression patterns (Kettle et al. 2003), and the plasticity and heritability of its leg-bearing segment (LBS) number (Vedel et al. 2008, Vedel et al. 2009) all employ descriptions of its morphologi- cal development. A more complete understanding of early post-embryonic stages is
S.J. White, T.J. Kells and A.J. Wilson
found abundant evidence for heritable variation underpinning personality (van Oers et al., 2005; Dingemanse et al., 2012 ; Oswald et al., 2013 ), though tests of genetic (co)variance structures remain limited. While we found no support here for POLS at the level of the individual phenotype, we suggest
Paola A. Olivero, David E. Vrech, Mariela A. Oviedo-Diego, Camilo I. Mattoni and Alfredo V. Peretti
, 501 - 508 . Weygoldt , P. & Paulus , H.F. ( 1979 ) Untersuchungen zur Morphologie, Taxonomie und Phylogenie der Chelicerata1 I. Morphologische Untersuchungen . J. Zool. Syst. Evol. Res. , 17 , 85 - 116 . Wilcockson , R.W. , Crean , C.S. & Day , T.H. ( 1995 ) Heritability of a sexually
A Descriptive Summary and Potential Explanation
V. , Gao , T. , Bhattacharya , S. , Angel , C. , Furman , D. , Shen-Orr , S. , Dekker , C. , Swan , G. , Maecker , H. , & Davis , M. ( 2014 ). Variation in the Human Immune System Is Largely Driven by Non-Heritable Influences . Cell , DOI: http://dx.doi.org/10.1016/j.cell.2014
Grant E. Brown, Pierre J.C. Chuard, Ebony E.M. Demers, Indar W. Ramnarine, Douglas P. Chivers and Maud C.O. Ferrari
. Dingemanse , N.J. , Van der Plas , F. , Wright , J. , Réale , D. , Schrama , M. , Roff , D.A. , Van der Zee , E. & Barber , I. ( 2009 ). Individual experience and evolutionary history of predation affect expression of heritable variation in fish personality and morphology . — Proc. Roy