Laboratory of Systematics of Vascular Plants, Botany Department, Instituto de Biociências, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves 9500, Porto Alegre, 91509-900, Rio Grande do Sul, Brazil.
Porto Alegre Botanical Garden, Secretaria Estadual do Meio Ambiente do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil.
J Plant Res. 2024 Sep;137(5):863-875. doi: 10.1007/s10265-024-01555-y. Epub 2024 Jul 10.
Reproductive isolation is one of the mechanisms of speciation. The two currently accepted subspecies of Parodia haselbergii (P. haselbergii subsp. haselbergii and P. haselbergii subsp. graessneri) were studied regarding flower traits, phenology, breeding systems and pollination. In addition, a principal component analysis with 18 floral characters and germination tests under controlled conditions were performed for both taxa. Pollination was studied in the field, in two localities of Southern Brazil. Pollinators were recorded through photos and film. Breeding system experiments were performed by applying controlled pollinations to plants excluded from pollinators. Both taxa mostly differ in asynchronous flowering periods, floral traits (including floral part measurements and nectar concentration) and pollinators. The flowers of both subspecies are functionally protogynous and perform remarkably long lifespans (≥ 15 days), both traits being novelties for Cactaceae. Whereas the reddish flowers of P. haselbergii subsp. haselbergii (nectar concentration: ca. 18%) are pollinated by hummingbirds of Thalurania glaucopis, the greenish flowers of P. haselbergii subsp. graessneri (nectar concentration: ca. 29%) are pollinated by Augochlora bees (Halictidae). Both subspecies are self-compatible, yet pollinator-dependent. The principal component analysis evidenced that both subspecies are separated, regarding flower traits. The seeds of both subspecies performed differently in the germination tests, but the best results were recovered at 20 °C and germination considerably decreased around 30 °C. In conclusion, all these results support that both taxa are in reproductive isolation, and can be treated as different species.
生殖隔离是物种形成的机制之一。目前被接受的 Parodia haselbergii 的两个亚种（P. haselbergii subsp. haselbergii 和 P. haselbergii subsp. graessneri）在花的特征、物候、繁殖系统和传粉方面进行了研究。此外，对这两个分类单元进行了基于 18 个花特征的主成分分析和控制条件下的发芽试验。在巴西南部的两个地点对传粉进行了实地研究。通过照片和录像记录传粉者。通过对排除在传粉者之外的植物进行控制授粉，进行了繁殖系统实验。两个分类单元主要在开花期不同步、花的特征（包括花部测量和花蜜浓度）和传粉者方面存在差异。两个亚种的花都是功能上的雌先熟，寿命非常长（≥15 天），这两个特征都是仙人掌科的新特征。P. haselbergii subsp. haselbergii 的红色花（花蜜浓度：约 18%）由 Thalurania glaucopis 的蜂鸟授粉，而 P. haselbergii subsp. graessneri 的绿色花（花蜜浓度：约 29%）由 Augochlora 蜜蜂（Halictidae）授粉。两个亚种都是自交亲和的，但依赖传粉者。主成分分析表明，两个亚种在花的特征方面是分离的。两个亚种的种子在发芽试验中的表现不同，但在 20°C 时效果最好，而在 30°C 左右时发芽率显著下降。总之，所有这些结果都支持这两个分类单元处于生殖隔离状态，可以被视为不同的物种。
