[A quantitative analysis of the effect of the initial conditions on the results of phylogenetic reconstructions]

Parameters of character description (homology, coding, weighting, ordering), of the context (outgroup and ingroup membership) belong to initial conditions of phylogenetic reconstructions. A principal possibility for the effects of the parameters on the results of these reconstructions to be evaluated numerically is shown. An algorithm of respective procedure is outlined which is based on combination of cladistic, principal component and dispersion (MANOVA) analyses. A study case is morphological diversity of mastoid bulla in the rodent families Gerbillidae, Dipodidae s. lato, Gliridae. The principal idea of the approach outlined is, first, to produce a set of cladograms under variable conditions determined by arbitrary altering the above parameters. Diversity of topology of these cladograms represented by respective distance matrixes is subsequently analyzed by MANOVA, the above parameters being treated as independent variables. This gives strictly quantitative and mutually commensurable estimates of the parameters influence on the topology of cladograms. It is shown that homology is the most and ordering is the least influential among character description parameters. Important effect of the context parameters is shown, as well.