An empirical evaluation of qualitative Hennigian analyses of protein electrophoretic data

MITOCHONDRIAL GENE TREES AND THE EVOLUTIONARY RELATIONSHIP OF MALLARD AND BLACK DUCKS

We assayed restriction site differences in mitochondrial DNA (mtDNA) within and among allopatric populations of the Mallard (Anas platyrhynchos) and the American Black Duck (A. rubripes). The observed mtDNA clones grouped into two phylogenetically distinct arrays that we estimate differ by about 0.8% in nucleotide sequence. Genotypes in one clonal array were present in both species, while genotypes in the other array were seen only in Mallards. In terms of the mtDNA "gene tree," the assayed Mallards exhibit a paraphyletic relationship with respect to Black Ducks, meaning that genealogical separations among some extant haplotypes in the Mallard predate the species separation. Evidence is advanced that this pattern probably resulted from demographically based processes of lineage sorting, rather than recent, secondary introgressive hybridization. However, haplotype frequencies were most similar among conspecific populations, so the Mallard and Black Ducks cluster separately in terms of a population phenogram. The results provide a clear example of the distinction between a gene tree and a population tree, and of the distinction between data analyses that view individuals versus populations as operational taxonomic units (OTUs). Overall, the mtDNA data indicate an extremely close evolutionary relationship between Mallards and Black Ducks, and in conjunction with the geographic distributions suggest that the Black Duck is a recent evolutionary derivative of a more broadly distributed Mallard-Black ancestor.

Amino acid sequences of P1 protamines and the phylogeny of eutherian mammals: a cladistic study

Amino acid and cDNA sequences of eutherian P1 protamines, known from publications of other authors, were compared by a cladistic method. Fish, toad and bird protamines were used for the pertinent "outgroup comparisons", i.e. they provided relevant data for the comparative alignment of the sequences and for the recognition of evolutionary trends. In the sequence positions compared, each amino acid was individually assigned as a plesiomorphic or apomorphic character state (qualitative treatment). The resulting phylogenetic tree (Fig. 2) is only partially in accordance with common ideas on eutherian phylogeny. Disagreements refer to the branching points of Perissodactyla, Lagomorpha and Rodentia.

Molecular evolution and phylogeny of the Drosophila virilis species group as inferred by two-dimensional electrophoresis

Systematic relationship among the 12 species of the Drosophila virilis species group, and Drosophila robusta, were investigated by the use of two-dimensional electrophoresis (2-DE). A total of 389 protein characters (about 200 loci) were scored and analyzed both phylogenetically and phenetically. The resulting phylogeny was found to be largely concordant with the current views of evolution among these species based on other independent morphological, chromosomal, electrophoretic, and immunological data sets, although some notable differences were observed. The 2-DE data also appeared to be useful for constructing a molecular clock to date the absolute times of divergence among the species. It appears from this analysis that the evolution of the major clades within the species group occurred about 20 million years ago. Previous suggestions that the rate of molecular evolution was different between the virilis and montana phylads was not confirmed. The technique of 2-DE seems to be an excellent tool for reconstructing phylogenies and should be particularly valuable for examining relatively closely related species.

Molecular evolution among some Drosophila species groups as indicated by two-dimensional electrophoresis

The evolutionary and phylogenetic relationships of seven Drosophila species groups (represented by D. melanogaster, D. mulleri, D. mercatorum, D. robusta, D. virilis, D. immigrans, D. funebris, and D. melanica) were investigated by the use of two-dimensional electrophoresis. The resulting phylogeny is congruent with the current views of evolution among these groups based on morphological characters and immunological distances. Previous studies indicated that the ability of one-dimensional electrophoresis to resolve relationships between distantly related taxa extended to about the Miocene [25 million years (Myr) ago], but the present study demonstrates that two-dimensional electrophoresis is a useful indicator of phylogeny even back to the Paleocene (65 Myr ago). In addition, two-dimensional electrophoresis is shown to be a useful technique for detecting slowly evolving structural proteins such as actins and tropomyosins.