  The asymptotic behavior of a subcritical Branching Process in Random
Environment (BPRE) starting with several particles depends on whether the BPRE
is strongly subcritical (SS), intermediate subcritical (IS) or weakly
subcritical (WS). %Descendances of particles for BPRE are not independent. In
the (SS+IS) case, the asymptotic probability of survival is proportional to the
initial number of particles, and conditionally on the survival of the
population, only one initial particle survives $a.s.$ These two properties do
not hold in the (WS) case and different asymptotics are established, which
require new results on random walks with negative drift. We provide an
interpretation of these results by characterizing the sequence of environments
selected when we condition on the survival of particles. This also raises the
problem of the dependence of the Yaglom quasistationary distributions on the
initial number of particles and the asymptotic behavior of the Q-process
associated with a subcritical BPRE.
