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وإن آسف اني افتح النت من بيتي وليس من الجامعة فلا يتاح لي إلا رؤية ال abstract:
امثلة سريعة:
Phylogenomics and the reconstruction of the tree of life.
Delsuc F, Brinkmann H, Philippe H.
Source
Canadian Institute for Advanced Research, Département de Biochimie, Centre Robert-Cedergren, Université de Montréal, Succursale Centre-Ville, Montréal, Québec H3C3J7, Canada.
Abstract
As more complete genomes are sequenced, phylogenetic analysis is entering a new era - that of phylogenomics. One branch of this expanding field aims to reconstruct the evolutionary history of organisms on the basis of the analysis of their genomes. Recent studies have demonstrated the power of this approach, which has the potential to provide answers to several fundamental evolutionary questions. However, challenges for the future have also been revealed. The very nature of the evolutionary history of organisms and the limitations of current phylogenetic reconstruction methods mean that part of the tree of life might prove difficult,
if not impossible, to resolve with confidence
http://www.ncbi.nlm.nih.gov/pubmed/15861208
ركزوا الآن جيدا جدا على الجملة التي ألونها باللون الاصفر
Phylogenetic classification and the universal tree.
Source
Canadian Institute for Advanced Research, Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Nova Scotia B3H 4H7, Canada.
ford@is.dal.ca
Abstract
From comparative analyses of the nucleotide sequences of genes encoding ribosomal RNAs and several proteins, molecular phylogeneticists have constructed a "universal tree of life," taking it as the basis for a "natural" hierarchical classification of all living things.
Although confidence in some of the tree's early branches has recently been shaken, new approaches could still resolve many methodological uncertainties. More challenging is evidence that most archaeal and bacterial genomes (and the inferred ancestral eukaryotic nuclear genome) contain genes
from multiple sources. If "chimerism" or "lateral gene transfer" cannot be dismissed as trivial in extent or limited to special categories of genes, then no hierarchical universal classification can be taken as natural.
Molecular phylogeneticists will have failed to find the "true tree," not because their methods are inadequate or because they have chosen the wrong genes, but because the history of life cannot properly be represented as a tree. However, taxonomies based on molecular sequences will remain indispensable, and understanding of the evolutionary process will ultimately be enriched, not impoverished.
http://www.ncbi.nlm.nih.gov/pubmed/10381871
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