We have performed a systematic analysis of the dynamics of different galaxy populations in galaxy groups from the 2dFGRS .
For this purpose we have combined all the groups into a single system , where velocities v and radius r are expressed adimensionally .
We have used several methods to compare the distributions of relative velocities of galaxies with respect to the group centre for samples selected according to their spectral type ( as defined by Madgwick et al. , 2002 ) , b _ { j } band luminosity and B - R colour index .
We have found strong segregation effects : spectral type I objects show a statistically narrower velocity distribution than that of galaxies with a substantial star formation activity ( type II-IV ) .
Similarly , the same behavior is observed for galaxies with colour index B - R > 1 compared to galaxies with B - R < 1 .
Bright ( M _ { b } < -19 ) and faint ( M _ { b } > -19 ) galaxies show the same segregation .
It is not important once the sample is restricted to a given spectral type .
These effects are particularly important in the central region ( R _ { p } < 0.5 R _ { vir } ) and do not have a strong dependence on the mass of the parent group .
These trends show a strong correlation between the dynamics of galaxies in groups and star formation rate reflected both by spectral type and by colour index .