Sex Ratios and Resource Allocation among Sexually Reproducing Plants of Rubus chamaemorus

Sex ratios and patterns of size variation and resource allocationwere investigated in the dioecious species Rubus chamaemorus.Sex ratios among flowering ramets varied from 6% to 40% of females.Female ramets were slightly, although not significantly, tallerthan males. It appeared that population effects (including bothgenetic population and environmental site effects) on plantsize and allocation patterns at flowering are considerably greaterthan sex effects. If both flowering and fruit production areconsidered, then female allocation to reproduction clearly exceedsmale allocation. In females, no significant relationship wasdetected between the mass of reproductive and vegetative tissues,while males did exhibit such a relationship. Reproductive effortwas less for tall males than for small males. Despite the occurrence of sexual reproduction, the main modeof reproduction in R. chamaemorus is vegetative propagation,which is the best strategy for reproduction in the unpredictableclimate of high latitudes but which leads to skewed sex ratios.As a consequence of vigorous vegetative reproduction, individualclones can grow to be large. The results of electrophoreticstudies show that the numbers of clones per population are low.Copyright1994, 1999 Academic Press Rubus chamaemorus, cloudberry, sex ratios, resource allocation, clonal structure, electrophoresis