Phylogenetic Analyses of Quasars and Galaxies
  Phylogenetic approaches have proven to be useful in astrophysics. We have
recently published a Maximum Parsimony (or cladistics) analysis on two samples
of 215 and 85 low-z quasars (z < 0.7) which offer a satisfactory coverage of
the Eigenvector 1-derived main sequence. Cladistics is not only able to group
sources radiating at higher Eddington ratios, to separate radio-quiet (RQ) and
radio-loud (RL) quasars and properly distinguishes core-dominated and
lobe-dominated quasars, but it suggests a black hole mass threshold for
powerful radio emission as already proposed elsewhere. An interesting
interpretation from this work is that the phylogeny of quasars may be
represented by the ontogeny of their central black hole, i.e. the increase of
the black hole mass. However these exciting results are based on a small sample
of low-z quasars, so that the work must be extended. We are here faced with two
difficulties. The first one is the current lack of a larger sample with similar
observables. The second one is the prohibitive computation time to perform a
cladistic analysis on more that about one thousand objects. We show in this
paper an experimental strategy on about 1500 galaxies to get around this
difficulty. Even if it not related to the quasar study, it is interesting by
itself and opens new pathways to generalize the quasar findings.
