Flowering phenology, pollen flow and fruit production in the andean shrub Befaria resinosa.

Abstract

In the eastern Andes of Colombia, the shrub Befaria resinosa (Ericaceae) has peaks of flowering that are separated by extended periods of low flower production. The effect that these fluctuations in flower production have on pollen flow was investigated by using fluorescent dye as a pollen analog. Dye applied to open flowers was dispersed over long distances more often during low flower production than during high flower production. Whether enhanced pollen dispersal during flowering lows is of benefit to individual plants is not clear. The proportion of flowers that set fruit is positively correlated with flower abundance, negating the possibility that increased pollen dispersal results in a higher rate of fruit production due to outbreeding effects. It is also difficult to attribute the pattern of fruit production to changes in pollinator visitation rates, which are negatively correlated with flower abundance in the case of hummingbirds and not correlated at all with flower abundance in the case of insects. An opportunistic, large-bodied hummingbird (Colibri coruscans) visits B. resinosa during high flowering and may be a particularly effective pollinator, accounting for some of the increase in the proportion of flowers setting fruit. Rainfall is positively correlated with flower production and may be an important factor in shaping flowering phenology, but it is not significantly correlated with the proportion of flowers setting fruits. The possibility that low-level flowering may counteract inbreeding that results from peak flowering is discussed.