Kp. Johnson et Md. Sorenson, COMPARING MOLECULAR EVOLUTION IN 2 MITOCHONDRIAL PROTEIN-CODING GENES(CYTOCHROME-B AND ND2) IN THE DABBLING DUCKS (TRIBE, ANATINI), Molecular phylogenetics and evolution (Print), 10(1), 1998, pp. 82-94
Rates of sequence evolution were estimated for the cytochrome b (cyt b
) and NADH dehydrogenase subunit 2 (ND2) genes using a phylogeny of th
e dabbling ducks (Tribe: Anatini) and outgroups. This speciose group w
as densely sampled, reducing the impact of undetected homoplasy on rat
e comparisons. Phylogenies based on sequences of the two gene regions
and various weighting schemes differed, but most of the differences in
volved weakly supported nodes. In addition, partition homogeneity test
s show that these differences were not due to statistically significan
t conflict between the data sets. Cyt b and ND2 also showed similar ra
tes and types of both nucleotide and amino acid substitutions. For bot
h genes, substitutions between isoleucine and valine and between alani
ne and threonine were most common; both of these substitution types ar
e the result of A-G transitions at first positions of codons, Rates of
sequence evolution varied substantially and significantly among nucle
otide positions, and even within a given codon position (first, second
, or third), rates were significantly heterogeneous among sites. Withi
n Anatini, cyt b and ND2 show similar levels of variation and homoplas
y, and are equally useful for reconstructing the species level phyloge
ny of this group. (C) 1998 Academic Press.