ISSN:
1615-6110
Keywords:
Rubiaceae
;
Rubieae
;
Droseraceae
;
Drosera
;
Nothofagaceae
;
Nothofagus
;
Aquifoliaceae
;
Ilex
;
rbcL
;
nucleotide substitution pattern
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Variation in chloroplastrbcL sequences was studied in representative species of four different lineages: the tribeRubieae (Rubiaceae), and the generaDrosera (Droseraceae),Nothofagus (Nothofagaceae) andIlex (Aquifoliaceae). Each lineage has its particular non-overlapping set ofrbcL polymorphic sites, indicating that common unconstrainedrbcL sites are not shared. Large differences in the rate and pattern of nucleotide substitution are observed among the four lineages. The genusIlex has the lowest rate of substitution, the lowest transition/transversion ratio, the lowest synonymous/replacement ratio and the lowest number of substitutions at the third codon position. An apparent relationship of these measures to the age of the lineages is observed. The A + T content and codon use among the four lineages are very similar and, apparently, cannot account for the observed differences in patterns of nucleotide substitution. However, the A + T content of the two bases immediately flanking the polymorphic sites is higher inIlex than in the other lineages. This could be correlated with the transversion/transition bias observed inIlex. The particularly low synonymous/replacement ratio found inIlex could also be explained by the small population sizes of species in this genus.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00984915
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