COLONIZATION DYNAMICS OF NEW PONDS, AND THE AGE STRUCTURE OF COLONIZING ALPINE NEWTS, TRITURUS-ALPESTRIS

Age-specific dispersal and colonization were investigated by monitorin g the colonization of a set of five newly-created ponds over three yea rs, and the age structure of colonizer individuals was compared to the age structure in two resident populations by means of skeletochronolo gy. Whereas the youngest adult individuals in the resident populations were 3 years old, most colonizers were 1-2 year-old adult newts. This study also shows that older newts participate in the colonization of new sites, as well as juveniles. As expected, the sex ratio of the fir st year colonizers was biased in favour of males. Juvenile dispersal a ppears adaptive in the context of metapopulation dynamics with patches experiencing rapid ecological succession. Sex-biased dispersal may be related to the mating system, and asymmetry in reproductive effort be tween the sexes.