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Nature article:
Unravelling angiosperm genome evolution by phylogenetic analysis of chromosomal
duplication events

Note:
...
Here we integrate a phylogenetic approach (relating chromosomal duplications to the
tree of life) with a genomic approach (mitigating information lost to diploidization) to
show that a genome-wide duplication post-dates the divergence of
arabidopsis from most dicots.
...
By using partial sequence data for many diverse taxa to better relate the
evolutionary history of completely sequenced genomes to the tree of life,
we foster comparative approaches to the study of genome organization,
consequences of polyploidy, and the molecular basis of quantitative traits.
....
It was recognized recently that even
small angiosperm genomes contain much duplication, but
robust application of this finding to comparative biology has
awaited a means to directly relate chromosomal events to the tree
of life in a manner that is not subject to the differing rates of various
molecular clocks.
....
we circumscribed 34 nonoverlapping
chromosomal segment pairs that include 23,177
Arabidopsis genes (representing 89% of the total) (Fig. 1a). Circumscription
of these segment pairs (here called the a group) is
conservative, as x2 tests comparing the observed number of gene
duplications comprising each pair to the number expected in a
chromosomal region of equal size if duplications are randomly
distributed over the genome, show a maximal random likelihood
of 2.8 £ 10284 (for a17). Of 2,851 (11%) genes in putatively nonduplicated
regions, 1,570 (55%) were near centromeres, and the rest
in gaps between the duplications.
sequence. By contrast, only 6?19% of Malvaceae and more distant
sequences clustered internally to the Arabidopsis syntenic
duplicates.
...

Posted by 西瓜 at January 11, 2004 10:45 PM