Pollinator and habitat-mediated selection as potential contributors to ecological speciation in two closely related species
Pollinator and habitat-mediated selection as potential contributors to ecological speciation in two closely related species
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传粉者和栖息地介导的选择作为两个密切相关物种生态物种形成的潜在贡献者
DOI：
10.1093/evlett/qrad060
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发表时间：
2023
影响因子：
5
通讯作者：
Crowell, Madison
中科院分区：
文献类型：
--
作者：
Campbell, Diane R;Powers, John M;Crowell, Madison
在生态物种形成中，早期物种由于基于生态学的自然选择而分化。在开花植物中，不同的传粉媒介可以介导这种选择（传粉媒介介导的分化选择），或者两个物种栖息地之间不同的环境特征可以介导这种选择（环境介导的分化选择）。虽然这些机制被很好地理解，但它们很少得到严格的测试，因为很少有研究表明，在近亲物种的不同位点上，既包括影响授粉的花性状，也包括影响生存的营养性状。本研究在两个亲本种和一个杂交点的普通花园中，每个地点都包含高级代杂交品种和亲本种，以测试这些形式的生态物种形成在usipomopsis属植物中。分析了3个营养性状（比叶面积、叶片毛状体和光合水分利用效率）和5个花性状（花冠长度和宽度、花药插著、花瓣颜色和花蜜产量）对适合度成分（开花存活率和单花种子）的影响。这些性状在杂交带的海拔梯度上表现出较强的曲线，较窄的曲线在理论上反映了较强的选择或较高的遗传变异。具有长花冠和嵌着花药的植物，其每朵花的种子数较高，而在聚集型植物中，选择倾向于相反的条件，这是不同选择的标志。相比之下，在任何营养性状上都没有发现由于生存变异而产生的分化选择。杂交区内的选择与杂交区内的选择最为相似。aggregatasite。在各性状中，分化选择的强度与变异宽度的相关性不显著，而进化能力（标准化遗传方差）能更好地预测变异宽度。这些结果支持了传粉媒介介导的分化选择在生态物种形成中的作用，并说明了遗传变异在决定杂交带间分化的重要性。
In ecological speciation, incipient species diverge due to natural selection that is ecologically based. In flowering plants, different pollinators could mediate that selection (pollinator-mediated divergent selection) or other features of the environment that differ between habitats of 2 species could do so (environment-mediated divergent selection). Although these mechanisms are well understood, they have received little rigorous testing, as few studies of divergent selection across sites of closely related species include both floral traits that influence pollination and vegetative traits that influence survival. This study employed common gardens in sites of the 2 parental species and a hybrid site, each containing advanced generation hybrids along with the parental species, to test these forms of ecological speciation in plants of the genusIpomopsis. A total of 3 vegetative traits (specific leaf area, leaf trichomes, and photosynthetic water-use efficiency) and 5 floral traits (corolla length and width, anther insertion, petal color, and nectar production) were analyzed for impacts on fitness components (survival to flowering and seeds per flower, respectively). These traits exhibited strong clines across the elevational gradient in the hybrid zone, with narrower clines in theory reflecting stronger selection or higher genetic variance. Plants with long corollas and inserted anthers had higher seeds per flower at theIpomopsis tenuitubasite, whereas selection favored the reverse condition at theIpomopsis aggregatasite, a signature of divergent selection. In contrast, no divergent selection due to variation in survival was detected on any vegetative trait. Selection within the hybrid zone most closely resembled selection within theI. aggregatasite. Across traits, the strength of divergent selection was not significantly correlated with width of the cline, which was better predicted by evolvability (standardized genetic variance). These results support the role of pollinator-mediated divergent selection in ecological speciation and illustrate the importance of genetic variance in determining divergence across hybrid zones.