transplant experiments with Impatiens capensis

Summary. Modified reciprocal transplant experiments were conducted with the annual plant species Impatiens eapensis and L pallida to partition the influence of environment on fitness into two components; that of (1) conspecific neigh-bours occupying each transplant site, and (2) the abiotic and biotic features of each site exclusive of the conspecific neighbours. In the within-species reciprocal transplant se-ries, differences in survivorship and fruit production by cle-istogamous flowers were attributable primarily to the effect of conspecific neighbours. In addition, plants surrounded by neighbours from the site of origin produced significantly more fruit from chasmogamous flowers compared with plants surrounded by neighbours from the alien site. In the between-species r ciprocal transplant series, one trans-plant site was consistently associated with greater survivor-ship and fruit production regardless of the identity of neigh-bouring plants. The results suggest hat different aspects of the environment in these reciprocal transplant experi-ments (conspecific neighbours, other species, physical fac-tors) determine fitness in different situations