Evolutionary trees for the genus Bordetella.

Recent data on enzyme electrophoretic mobility and DNA sequences for pertussis toxin allow the construction of evolutionary trees for various strains belonging to the genus Bordetella. In contrast to previous analyses, these data can be seen to support the separate clustering of Bordetella pertussis strains, in agreement with the traditional classification based on other phenotypic characteristics. An earlier argument placing the divergence of B. pertussis and B. parapertussis before 1912 does not follow from the evolutionary trees proposed here, which also have different implications for several other claims concerning the evolution of these strains.