EFFECT OF DENSITY AND FLOWER SIZE ON THE REPRODUCTIVE SUCCESS OF NOTHOSCORDUM GRAMINUM (ALLIACEAE)

Abstract

The size, form and color are signals used by flowers to attract their pollinators. Large and showy color flowers usually
receive higher pollinators visitation rates. According to the optimal forage theory, pollinators would tend to visit
flower patches where they obtain the maximum reward regarding the energy expenditure in flower search. In high
density patches, flowers are very close each other, hence, flower discrimination by pollinators would tend to be low.
In low density patches, however, where the forage effort is greater, larger flowers are usually associated with higher
rewards and would receive higher pollinators visitation achieving greater fitness than co-especifics with smaller
flowers. In the present study we assessed the effects of flower density and size on the reproductive success (RS) of
Nothoscordum gramineum. Four patches of different densities were delimited and the flowers size of the half of
individuals at each patch was manually reduced. Results showed that RS was significantly greater in individuals with
larger flowers. Additionally, density has a positive effect on RS, especially in large size flowers. Nevertheless, fruition
success reached maximum values in patches of intermediate density. Individuals with cut flowers did not varied the RS
with the variation of the density, suggesting that flower size is the most important attribute measured as advertisement
by pollinators in N. gramineum. Our results do not support the hypothesis that in high density patches, flower
displays have low importance.