124 research outputs found
Inheritance of Isoenzymes in European Beech (Fagus sylvatica L.)
Segregation of isoenzymes was studied among 34 full-sib families of Fagus sylvatica L. by means of gel electrophoresis. Of the 16 enzyme systems analyzed, two showed substantial tissue-specific expression of isoenzymes. The remaining 14 enzyme systems are controlled genetically by at least 20 polymorphic gene loci, three of which were inferred from additional population studies. The inheritance of the complex system of 6PGDH is studied in detail. A 20-locus nomenclature is suggested, including 78 codominant alleles. Analyses of two-locus combinations did not reveal linkage between any of the tested gene loc
Do maternal environmental conditions during reproductive development induce genotypic selection in Picea abies?
In forest trees, environmental conditions during reproduction can greatly
influence progeny performance. This phenomenon probably results from
adaptive phenotypic plasticity but also may be associated with genotypic
selection. In order to determine whether selective effects during the
reproduction are environment specific, single pair-crosses of Norway spruce
were studied in two contrasted maternal environments (warm and cold
conditions). One family expressed large and the other small phenotypic
differences between these crossing environments. The inheritance of genetic
polymorphism was analysed at the seed stage. Four parental genetic maps
covering 66 to 78% of the genome were constructed using 190 to 200 loci.
After correcting for multiple testing, there is no evidence of locus under
strong and repeatable selection. The maternal environment could thus only
induce limited genotypic-selection effects during reproductive steps, and
performance of progenies may be mainly affected by a long-lasting epigenetic
memory regulated by temperature and photoperiod prevailing during seed
production.L'environnement maternel induit-il une sélection génotypique
durant les différents stades de reproduction chez Picea
abies ?. Chez les arbres forestiers, les conditions environnementales durant la
reproduction peuvent influencer les performances des descendants. Ce
phénomène reflète probablement la plasticité
phénotypique, mais également il pourrait être associé à une
sélection génotypique. Afin de déterminer si des effets
sélectifs durant la reproduction sont spécifiques d'un environnement
donné, deux familles d'épicéa commun non apparentées ont
été obtenues par croisements dirigés dans deux environnements
maternels contrastés (conditions chaude et froide). La première
famille exprimait de larges différences phénotypiques entre les deux
environnements tandis que la seconde ne montrait pas de différence
significative. La transmission des polymorphismes génétiques a
été étudiée au stade de la graine. Quatre cartes
génétiques parentales couvrant 66 à 78 % du génome ont
été construites. Aucun effet de sélection n'a été mis en
évidence aux différents locus étudiés. L'environnement
maternel n'induirait donc que des effets de sélection génotypique
relativement faibles durant les stades de la reproduction. Les performances
des descendants seraient principalement affectées par une mémoire
épigénétique durable régulée par la température et
la photopériode régnant durant la production des graines
The richest superclusters. I. Morphology
We study the morphology of the richest superclusters from the catalogues of
superclusters of galaxies in the 2dF Galaxy Redshift Survey and compare the
morphology of real superclusters with model superclusters in the Millennium
Simulation. We use Minkowski functionals and shapefinders to quantify the
morphology of superclusters: their sizes, shapes, and clumpiness. We generate
empirical models of simple geometry to understand which morphologies correspond
to the supercluster shapefinders. We show that rich superclusters have
elongated, filamentary shapes with high-density clumps in their core regions.
The clumpiness of superclusters is determined using the fourth Minkowski
functional . In the - shapefinder plane the morphology of
superclusters is described by a curve which is characteristic to
multi-branching filaments. We also find that the differences between the fourth
Minkowski functional for the bright and faint galaxies in observed
superclusters are larger than in simulated superclusters.Comment: 14 pages, 8 figures, submitted to Astronomy and Astrophysic
Toward understanding rich superclusters
We present a morphological study of the two richest superclusters from the
2dF Galaxy Redshift Survey (SCL126, the Sloan Great Wall, and SCL9, the
Sculptor supercluster). We use Minkowski functionals, shapefinders, and galaxy
group information to study the substructure of these superclusters as formed by
different populations of galaxies. We compare the properties of grouped and
isolated galaxies in the core region and in the outskirts of superclusters. The
fourth Minkowski functional and the morphological signature -
show a crossover from low-density morphology (outskirts of supercluster) to
high-density morphology (core of supercluster) at mass fraction . The galaxy content and the morphology of the galaxy populations in
supercluster cores and outskirts is different. The core regions contain a
larger fraction of early type, red galaxies, and richer groups than the
outskirts of superclusters. In the core and outskirt regions the fine structure
of the two prominent superclusters as delineated by galaxies from different
populations also differs. Our results suggest that both local (group/cluster)
and global (supercluster) environments are important in forming galaxy
morphologies and colors (and determining the star formation activity). The
differences between the superclusters indicate that these superclusters have
different evolutional histories (Abridged).Comment: 23 pages, accepted for publication in The Astrophysical Journa
Embryology and bony malformations of the craniovertebral junction
BACKGROUND: The embryology of the bony craniovertebral junction (CVJ) is reviewed with the purpose of explaining the genesis and unusual configurations of the numerous congenital malformations in this region. Functionally, the bony CVJ can be divided into a central pillar consisting of the basiocciput and dental pivot and a two-tiered ring revolving round the central pivot, comprising the foramen magnum rim and occipital condyles above and the atlantal ring below. Embryologically, the central pillar and the surrounding rings descend from different primordia, and accordingly, developmental anomalies at the CVJ can also be segregated into those affecting the central pillar and those affecting the surrounding rings, respectively. DISCUSSION: A logical classification of this seemingly unwieldy group of malformations is thus possible based on their ontogenetic lineage, morbid anatomy, and clinical relevance. Representative examples of the main constituents of this classification scheme are given, and their surgical treatments are selectively discussed
Broad-scale genetic homogeneity in natural populations of common hazel (Corylus avellana) in Ireland
The importance of the altricial – precocial spectrum for social complexity in mammals and birds:A review
Various types of long-term stable relationships that individuals uphold, including cooperation and competition between group members, define social complexity in vertebrates. Numerous life history, physiological and cognitive traits have been shown to affect, or to be affected by, such social relationships. As such, differences in developmental modes, i.e. the ‘altricial-precocial’ spectrum, may play an important role in understanding the interspecific variation in occurrence of social interactions, but to what extent this is the case is unclear because the role of the developmental mode has not been studied directly in across-species studies of sociality. In other words, although there are studies on the effects of developmental mode on brain size, on the effects of brain size on cognition, and on the effects of cognition on social complexity, there are no studies directly investigating the link between developmental mode and social complexity. This is surprising because developmental differences play a significant role in the evolution of, for example, brain size, which is in turn considered an essential building block with respect to social complexity. Here, we compiled an overview of studies on various aspects of the complexity of social systems in altricial and precocial mammals and birds. Although systematic studies are scarce and do not allow for a quantitative comparison, we show that several forms of social relationships and cognitive abilities occur in species along the entire developmental spectrum. Based on the existing evidence it seems that differences in developmental modes play a minor role in whether or not individuals or species are able to meet the cognitive capabilities and requirements for maintaining complex social relationships. Given the scarcity of comparative studies and potential subtle differences, however, we suggest that future studies should consider developmental differences to determine whether our finding is general or whether some of the vast variation in social complexity across species can be explained by developmental mode. This would allow a more detailed assessment of the relative importance of developmental mode in the evolution of vertebrate social systems
Intra- and interpopulational genetic variation in juvenile populations of Quercus robur L and Quercus petraea Liebl
In each of 5 2-year-old populations of Quercus robur and Q petraea (single and multipopulation samples), genetic variation was quantified with respect to 13 polymorphic enzyme coding gene loci. Genetic control and inheritance of isoenzymes was verified beforehand by means of analyses of full-sib families. The observed average heterozygosities were 21.3% Q robur and 21.9% for Q petraea (conditional heterozygosities of 56.6 and 56.7 respectively). The mean number of alleles per locus is 3.2 for Q robur and 3.1 for Q petraea. The relatively small genetic diversities indicate minor polymorphisms. The genetic distances between pairs of samples indicate remarkable differences between populations. Most of the single population samples could be proven to share a smaller proportion of the entire gene pool than each of the multipopulation samples. There is a strong genetic similarity between Q robur and Q petraea in terms of common alleles. It is concluded that, more than in other species, large genetic variation must be incorporated into oak population in order to maintain the ability of these species to adapt to heterogeneous environments.Variabilité génétique intra- et interpopulation dans de jeunes populations de Quercus robur L et de Quercus petraea Liebl. La variablité générique a été estimée dans 5 populations de Quercus robur et 5 populations de Q petraea à partir de 13 loci polymorphes contrôlant l'expression d'enzymes. L'hérédité mendélienne des isozymes a été au préalable vérifiée par l'étude de ségrégation dans les croisements contrôlés. Les valeurs moyennes de l'hétérozygotie observée sont de 21,3% chez Q robur et 21,9% chez Q petraea. Les mêmes valeurs pour les hétérozygoties conditionnelles sont de 56,6% et 56,7%. Le nombre moyen d'allèles est de 3,2 pour Q robur et 3,1 pour Q petraea. Les diversités génétiques sont relativement peu élevées. Les distances génétiques entre populations indiquent de très fortes différences entre elles. Les populations prises individuellement partagent une partie plus faible de l'ensemble du pool génétique que les populations regroupées entre elles. Les allèles communs indiquent une très forte similarité entre Q robur et Q petraea. En conclusion, il est recommandé de conserver une variabilité génétique élevée dans les chênaies de manière à maintenir leur aptitude à s'adapter à des milieux hétérogènes
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