Flower morphology as a predictor of pollination mode in a biotic to abiotic pollination continuum
Flower morphology as a predictor of pollination mode in a biotic to abiotic pollination continuum
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DOI：
10.1093/aob/mcad069
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发表时间：
2023-05-26
期刊：
影响因子：
4.2
通讯作者：
Di Stilio，Veronica S.
中科院分区：
文献类型：
--
作者：
Martinez-Gomez，Jesus;Park，Seongjun;Di Stilio，Veronica S.
背景和目的风传粉在开花植物中反复进化，然而将风传粉综合征作为一组完整的花性状的识别可能是难以捉摸的。毛茛科（Thalictrum）是一种温带多年生草本植物，它们从昆虫传粉多次过渡到风传粉，同时也表现出混合传粉，为在生物到非生物连续体中测试花形态和传粉模式之间的进化相关性提供了一个理想的系统。此外，在这个属中缺乏花器官融合，可以在没有这种特征的情况下测试传粉媒介的专门化。方法利用6个叶绿体位点扩展了该属植物的系统发育取样，这使我们能够根据花的形态来测试物种是否聚集成不同的授粉综合征。然后，我们利用多变量分析对开花性状进行分析，然后对新出现的花形态进行祖先状态重建，并确定这些性状是否在布朗运动的贝叶斯框架下进化相关。主要结果花性状可划分为5个簇，考虑系统发育亲缘关系后减少为3个簇，且与花形态和相关传粉媒介基本一致。多变量进化分析发现，花生殖结构（花柱、柱头、花丝和花药）的长度之间存在正相关关系。较短的生殖结构反映了昆虫传粉的物种和进化枝，而较长的生殖结构反映了风传粉的物种和进化枝，这与生物和非生物传粉媒介施加的选择压力相一致。结论尽管在形态空间分布的极端情况下，可检测到的整型花性状组与风媒或虫媒传粉相关，但也可能存在一种中间的混合传粉模式形态空间。因此，我们的数据广泛地支持了从趋同进化中可检测到的花形态的存在，这是thalictrum传粉模式进化的基础，可能是通过不同的路径从祖先的混合传粉状态。
Background and AimsWind pollination has evolved repeatedly in flowering plants, yet the identification of a wind pollination syndrome as a set of integrated floral traits can be elusive.Thalictrum(Ranunculaceae) comprises temperate perennial herbs that have transitioned repeatedly from insect to wind pollination while also exhibiting mixed pollination, providing an ideal system to test for evolutionary correlation between floral morphology and pollination mode in a biotic to abiotic continuum. Moreover, the lack of floral organ fusion across this genus allows testing for specialization to pollination vectors in the absence of this feature.MethodsWe expanded phylogenetic sampling in the genus from a previous study using six chloroplast loci, which allowed us to test whether species cluster into distinct pollination syndromes based on floral morphology. We then used multivariate analyses on floral traits followed by ancestral state reconstruction of the emerging flower morphotypes and determined whether these traits are evolutionarily correlated under a Bayesian framework with Brownian motion.Key ResultsFloral traits fell into five distinct clusters, which were reduced to three after considering phylogenetic relatedness and were largely consistent with flower morphotypes and associated pollination vectors. Multivariate evolutionary analyses found a positive correlation between the lengths of floral reproductive structures (styles, stigmas, filaments and anthers). Shorter reproductive structures tracked insect-pollinated species and clades in the phylogeny, whereas longer structures tracked wind-pollinated ones, consistent with selective pressures exerted by biotic vs. abiotic pollination vectors, respectively.ConclusionsAlthough detectable suites of integrated floral traits acrossThalictrumwere correlated with wind or insect pollination at the extremes of the morphospace distribution, a presumed intermediate, mixed pollination mode morphospace was also detected. Thus, our data broadly support the existence of detectable flower morphotypes from convergent evolution underlying the evolution of pollination mode inThalictrum, presumably via different paths from an ancestral mixed pollination state.