| Abstract: | The breeding strategies of 52 Galápagos Islands angiosperms from 30 families were examined. Controlled pollinations were performed to determine if self-incompatiblity was more prevalent than previously thought, thus acting as an enforcer of outcrossing, or if instead, both dioecism and self-incompatibility are poorly represented and self-compatibility is the rule. The plants tested were located in each of the seven major vegetation zones on the southern slope of Isla Santa Cruz. Fruit and seed yields were compared between tagged but uncovered flowers (controls) and others that were subjected to various manipulations. Of the 52 species studied, one was dioecious, 11 yielded inconclusive results, and the remaining 40 showed self-compatibility. All but three of the latter group also demonstrated automatic self-pollination. This study suggests that on the Galápagos Islands hermaphroditic and dioecious plants occur in relatively the same proportions as found in their mainland source areas. Of the two hermaphroditic breeding strategies considered in this study, self-compatibility and self-incompatibility, the former is highly represented in the Galápagos flora. |
