Department of Biology, University of Puerto Rico, Río Piedras Campus, P.O. Box 23360, San Juan, Puerto Rico 00931-3360 USA.
Am J Bot. 2009 Dec;96(12):2270-8. doi: 10.3732/ajb.0900026. Epub 2009 Nov 20.
Traits associated with self-pollination are common features of island plant communities. In this work, we studied the pollination biology and the breeding system of Harrisia portoricensis, an island columnar cactus, to test for the presence of inbreeding and inbreeding depression. For H. portoricensis, which bears flowers with typical outcrossing morphology, the results from 322 h of direct observations and videotaping showed that visits to flowers by animals were uncommon. Controlled pollinations demonstrated that H. portoricensis has a partially self-compatible breeding system that it is not autogamous and thus requires an external mechanism for the movement of pollen to set fruit. We detected differences in seed size, seed mass, germination success, and multiplicative fitness estimates between self- and cross-pollination treatments. We found that progeny resulting from natural and self-pollination treatments showed signs of inbreeding depression compared with progeny resulting from cross-pollination; however, the magnitude of the inbreeding depression was less than 50%. Our combined results suggest that for this species an endogamous breeding system should be favored by natural selection.
与自花授粉相关的特征是岛屿植物群落的常见特征。在这项工作中，我们研究了波多黎各哈里斯仙人掌的传粉生物学和繁殖系统，以检验其是否存在近交和近交衰退。对于具有典型异交形态的花朵的 H. portoricensis 来说，通过 322 小时的直接观察和录像显示，动物对花朵的访问并不常见。受控授粉表明，H. portoricensis 具有部分自交亲和的繁殖系统，它不是自交的，因此需要外部机制来移动花粉以结实。我们检测到自交和异交处理之间种子大小、种子质量、发芽成功率和乘法适合度估计值的差异。我们发现，与异交处理产生的后代相比，来自自然和自交处理的后代表现出近交衰退的迹象；然而，近交衰退的幅度小于 50%。我们的综合结果表明，对于这个物种，内婚繁殖系统应该受到自然选择的青睐。
