Variation in gender and flower-size dimorphism in the dioecious tree Dombeya ciliata, an endemic to La Reunion Island

The genus Dombeya is an important component of tropical forests in west Afr ica, Madagascar, and the Mascarene islands, bur little is known about the r eproductive biology of its members. In this study, we quantified gender var iation and flower-size variation in three populations of the dioecious tree Dombeya ciliata, an endemic of La Reunion Island (Indian Ocean). Variation among the three populations was observed for three characters. First, the high elevation population had strict males and females, whereas in the two low elevation populations, males were inconstant, with > 50 percent of the males set a small number of fruit. Second, females showed greater seed prod uction at high elevation. Third, flower-size dimorphism was greater at high elevation because male flowers were larger than female flowers.