1. Settlement in a new environment is a key phase in effective dispers
al. We investigated this phase in the common lizard (Lacerta vivipara
Jacquin) by an experimental introduction of known individuals. 2. Intr
oducing lizards in an already occupied environment revealed a prior-re
sidence advantage and some differences in the ability of individuals t
o face a new environment under conditions of high intraspecific compet
ition. 3. Transplanted individuals (TI) died in larger numbers than re
sident ones (RI) immediately after the introduction, except for juveni
les. this prior-residence advantage could arise from the difference of
familiarity with the local environment or from a dominant behaviour o
f RI on TI. 4. TI which survived the first winter after the introducti
on survived better than RI afterwards. However, surviving TI females p
aid a cost in their reproduction. 5. Surviving TI were not a random su
bset of the initial sample: smaller adult males and leaner adult femal
es were selected. These selective responses arose from the transplanta
tion since they were not observed in non-manipulated populations. 6. A
comparison of characteristics between natural transient or immigrant
individuals and TI survivors revealed: (i) TI male and yearling surviv
ors may have been transients or immigrants in their site of origin; (i
i) TI adult female survivors were not transients nor immigrants in the
ir site of origin. The latter result questions the use of introduction
experiments to test dispersal ability. Strictly. introduction experim
ents only test settlement ability.