Smithsonian Tropical Research Institute, Apartado 2072, Ancón, Balboa, Republic of Panama.
Am J Bot. 2001 Sep;88(9):1527-34.
Androdioecy is a rare sexual system in nature, as predicted theoretically. Among the androecious species reported so far, Castilla elastica (Moraceae) is unique in that flowers are unisexual and staminate and pistillate flowers on cosexual plants are produced on different inflorescences. In addition, inflorescence structure of staminate inflorescences on males and staminate and pistillate inflorescences on cosexes is markedly different. Staminate inflorescences on males are bivalvate, while staminate inflorescences on cosexes are "fig-like" and urceolate. Pistillate inflorescences are discoidal. The difference may reflect different roles and requirements of the three inflorescences in pollination and protection from herbivores. This study reports thrips pollination of C. elastica, demonstrated by a pollinator introduction experiment. Thrips pollination of the species may be an example of mutualism originating from plant-herbivore interactions. In the Moraceae, shifts from simple herbivores on flowers to pollinators might have occurred many times, evolving into diverse pollination systems including the fig-fig wasp mutualism. The family, of which little is known about pollination systems, provides interesting and unique opportunities to study evolution of pollination systems and roles of nonpollinating associates of inflorescences.
雌雄同体是自然界中一种罕见的性系统，这在理论上是有预测的。在迄今为止报道的雌雄同体物种中，Castilla elastica（桑科）是独特的，因为其花是单性的，雄花和雌花在同株植物上产生于不同的花序。此外，雄花上的花序结构与同株植物上的雄花和雌花的花序结构明显不同。雄花上的花序是双瓣的，而同株植物上的雄花和雌花的花序呈“榕果状”和壶状。雌花上的花序是盘状的。这种差异可能反映了这三种花序在传粉和免受食草动物侵害方面的不同作用和要求。本研究通过传粉者引入实验报告了 C. elastica 的蓟马传粉，证明了这一点。该物种的蓟马传粉可能是植物-食草动物相互作用起源的互利共生的一个例子。在桑科中，从简单的花食草动物到传粉者的转变可能发生了多次，进化出了包括榕果榕小蜂互利共生在内的多种传粉系统。这个科的传粉系统知之甚少，为研究传粉系统的进化和花序非传粉伴生物的作用提供了有趣而独特的机会。
