INCUMBENT ADVANTAGE IN COMMON LIZARDS AND THEIR COLONIZING ABILITY

1. Settlement in a new environment is a key phase in effective dispersal. We investigated this phase in the common lizard (Lacerta vivipara Jacquin) by an experimental introduction of known individuals. 2. Introducing lizards in an already occupied environment revealed a prior-residence advantage and some differences in the ability of individuals to face a new environment under conditions of high intraspecific competition. 3. Transplanted individuals (TI) died in larger numbers than resident ones (RI) immediately after the introduction, except for juveniles. this prior-residence advantage could arise from the difference of familiarity with the local environment or from a dominant behaviour of RI on TI. 4. TI which survived the first winter after the introduction survived better than RI afterwards. However, surviving TI females paid a cost in their reproduction. 5. Surviving TI were not a random subset of the initial sample: smaller adult males and leaner adult females were selected. These selective responses arose from the transplantation 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 survivors may have been transients or immigrants in their site of origin; (ii) TI adult female survivors were not transients nor immigrants in their site of origin. The latter result questions the use of introduction experiments to test dispersal ability. Strictly. introduction experiments only test settlement ability.