Pre-zygotic reproductive isolation between two synchronopatric Opuntia (Cactaceae) species in the Brazilian Chaco
Pre-zygotic reproductive isolation between two synchronopatric Opuntia (Cactaceae) species in the Brazilian Chaco
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DOI：
10.1111/plb.13077
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发表时间：
2020-01-08
期刊：
影响因子：
3.9
通讯作者：
Sigrist, M. R.
中科院分区：
文献类型：
--
作者：
Fachardo, A. L. S.;Sigrist, M. R.
仙人掌科（仙人掌科）以杂交和倍化率高而闻名，这导致了新物种的形成。在巴西查科地区发现了两个同域亲缘关系较近的种：O. elata和O. retrosa，这使我们能够验证这两个物种合子前生殖隔离机制的假设。通过花期和花生物学的监测，比较了花结构的形态变化，进行了种内和种间异花授粉试验，记录了访花者和传粉者的相互作用。开花是季节性和高度同步的。花生物学也表现出类似的策略，尽管在许多比较的结构中花的形态差异很大，但这种形态差异并不导致选择专属的传粉者。访花者和传粉者是两个物种共有的寡聚蜜蜂。红豆和逆转录紫豆是自相容的。而种间异花授粉（双向）导致萌发，花粉管不穿透柱头。红麻与逆转录红麻亲缘关系密切；然而，它们是孤立的，在巴西查科不杂交。结果表明，这两种植物均具有较弱的授粉前屏障，而花粉-雌蕊不亲和性（即授粉后屏障）对它们具有较强的隔离作用。
Opuntia (Cactaceae) is known for high rates of hybridization and ploidisation, resulting in the formation of new species. The occurrence of two sympatric and closely related species of Opuntia, O. elata and O. retrorsa, in Brazilian Chaco enabled us to test the hypothesis that pre-zygotic reproductive isolation mechanisms operate in both species. We monitored the flowering period, as well as floral biology, and compared the morphological variation of floral structures through measurements, performed intra- and interspecific cross-pollination tests, and recorded the guild of floral visitors and pollinators. Flowering was seasonal and highly synchronous. Floral biology exhibits similar strategies, and although floral morphology differs significantly in many of the compared structures, such morphological variation does not result in the selection of exclusive pollinators. Floral visitors and pollinators are oligolectic bees shared by both species. Opuntia elata and O. retrorsa are self-compatible. While interspecific cross-pollination (bidirectional) resulted in germination, the pollen tube did not penetrate the stigma. Opuntia elata and O. retrorsa are closely related; however, they are isolated and do not hybridise in Brazilian Chaco. We found that both have weak pre-pollination barriers, but that they are strongly isolated by pollen-pistil incompatibility, i.e. post-pollination barrier.