Molecular systematic studies generally assume that gene trees are reasonable estimates of species trees. We tested the validity of this assumption in the pigeons and doves (Aves: Columbiformes) by comparing phylogenies derived from nuclear (beta-fibrinogen intron 7) and mitochondrial (cytochrome b) genes. Trees derived from the two genes when analyzed separately contained many nodes in common. A partition homogeneity test revealed no significant incongruence between trees derived from the two genes; so, we combined nuclear and mitochondrial data in subsequent phylogenetic analyses. The resulting tree, which was highly resolved and generally well supported, contained a strong biogeographic component. The rate of nucleotide substitution for the nuclear intron was approximately six times slower than that of cytochrome b. This resulted in a much higher consistency index for trees derived from the intron because of the low level of multiple substitution. However, the degree of resolution and support for trees reconstructed from the two genes was similar. We also examined the transition and transversion substitution rates for the genes. Third position transversions for cytochrome b accumulated linearly with intron divergence, suggesting low levels of multiple substitution for third position transversions.

Copyright 2000 Academic Press.