Accelerated rate of evolution in SSU rDNA of Nematoda

Wurff, Andre vander Andre.vanderWurff at wur.nl
Thu Feb 26 06:59:43 EST 2004


Dear all,

We are wrestling to explain the finding that recently derived nematodal
clades have a significant higher rate of evolution that older clades
(Relative rate tests). In fact, we witness an increase in evolutionary
rate from primitive clades towards more recently derived clades.

Materials & Methods:
The program Phyltest {Kumar, 1995} was used to conduct relative rate
tests to compare the evolutionary rates between different groups of
nematodes. This program conducts the relative rate tests according to
Takezaki et al. {Takezaki, 1995}. Kimura's distance {Kimura, 1980} with
the gamma correction calculated by Modeltest was used to calculate
pairwise distances. All groups were tested pairwise and the sistergroup
to the two groups compared (not necessarily the outgroups to the phylum)
was used as outgroup when calculating the distances to get the best
result {Kumar, 1995}.

1. Can anyone help us in finding an explanation for this phenomenon ?
(e.g. relevant articles/opinions/vicariance/life hostory traits ?)
2. Do we have to correct for this in a phylogenetic analysis (in
MP/Bayesian/NJ trees) ?

Best regards,

Andre van der Wurff


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