The aim of the study is to investigate the impact of reproduction and
genetic variation on the persistence of populations of the prealpine,
monocarpic Saxifraga mutata L. The species grows on erosion slopes or
rocks, and its local populations are often small and isolated. Crossin
g experiments resulted in better seed-set than selfing, but both yield
ed viable seeds. Agamospermy did not occur. In an early-successional s
pecies like S. mutata, successful selfing is important in the coloniza
tion of new habitats. Flowers of S. mutata were visited by Syrphidae a
nd unspecialized Hymenoptera. A germination rate of 40% was reached in
cultivation after 20 weeks but germination continued until the end of
the experiment after 92 weeks. Seeds stored dry for 30 months at room
temperature mostly lost their germinability. In natural habitats, see
dlings were found almost throughout the year with a peak in spring. Su
itable safe sites were small patches of open soil, bare marl on erosio
n slopes, and rock crevices. AU individuals investigated were diploid
with 2n = 26. Allozyme electrophoresis showed a lack of segregation wi
thin the populations. Intra- and interpopulation genetic variation was
low. These results were in partial disagreement with theoretical expe
ctations in a mixed mating species. It is concluded that demographic r
ather than generic processes are the main cause of extinction of popul
ations of S. mutata, at least in the short-term. (C) 1996 The Linnean
Society of London