Nuclear and mitochondrial genes contain similar phylogenetic signal for pigeons and doves (Aves : Columbiformes)

Molecular systematic studies generally assume that gene trees are reasonabl e estimates of species trees. We tested the validity of this assumption in the pigeons and doves (Aves: Columbiformes) by comparing phylogenies derive d 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 nucl ear and mitochondrial data in subsequent phylogenetic analyses. The resulti ng tree, which was highly resolved and generally well supported, contained a strong biogeographic component. The rate of nucleotide substitution for t he nuclear intron was approximately six times slower than that of cytochrom e b, This resulted in a much higher consistency index for trees derived fro m the intron because of the low level of multiple substitution. However, th e degree of resolution and support for trees reconstructed from the two gen es was similar. We also examined the transition and transversion substituti on rates for the genes, Third position transversions for cytochrome b accum ulated linearly with intron divergence, suggesting low levels of multiple s ubstitution for third position transversions. (C) 2000 Academic Press.