The above tree was inferred from a dataset of Penny et al (91) on 11 mammals (edges are represented here with an equal length to focus on the tree topology). The data consists of DNA sequences of 191 nucleotides, obtained from several genes (alpha- and beta-hemoglobins, fibrinopeptides A and B, cytochrome c, myoglobins, alpha-chrystallin). The quartet set was obtained by running the FPM method on distances collected from the sequences, corrected according to the Jukes Cantor model of evolution (69) (for this purpose we used the dnadist program of the Phylip package (93).

Most of the inferred inter-species relationships coincide with what is expected, e.g., primates (human, gorilla, ape) and ungulates (cow, sheep, pig, horse). The Dog-Kangaroo group, also inferred by other methods, such as Neighbor Joining (Penny et al 91) and Maximum Parsimony, may be suspected of being incorrect, but Penny et al (91) report that they did not reach any firm conclusion concerning that edge.

The Qstar program takes here no decision concerning the position of the rodent and the rabbit, in relation to the other mammals. To date, there is no strong consensus on the position of the rodent and the recent polemic concerns the possibility of the rodent being at the root of the mammalian evolution (Graur et al 91, Erchia et al 96).



Last modified: Thu Mar 11 10:51:25 MET DST 1999