Grossenbacher Dena, Makler Leah, McCarthy Matthew, Fraga Naomi
Department of Biology, California Polytechnic State University, San Luis Obispo, CA, United States.
California Botanic Garden, Claremont, CA, United States.
Front Plant Sci. 2021 Mar 25;12:636133. doi: 10.3389/fpls.2021.636133. eCollection 2021.
Anthocyanin pigments are responsible for many of the vivid pink, purple, red, and blue flower colors across angiosperms and frequently vary within and between closely related species. While anthocyanins are well known to influence pollinator attraction, they are also associated with tolerance to abiotic stressors such as extreme temperatures, reduced precipitation, and ultraviolet radiation. Using a comparative approach, we tested whether abiotic variables predict floral anthocyanin in monkeyflowers (Phrymaceae) across western North America. Within two polymorphic species, we found that abiotic variables predicted flower color across their geographic ranges. In , the frequency of pink flowered (anthocyanin producing) individuals was greater in populations with reduced precipitation. In , the frequency of pink flowered individuals was greater at higher elevations that had reduced precipitation and lower temperatures but less ultraviolet radiation. At the macroevolutionary scale, across two parallel radiations of North American monkeyflowers, species with floral anthocyanins (pink, purple, or red corollas) occupied areas with reduced precipitation in but not . However, after accounting for phylogenetic relatedness, we found no evidence for the joint evolution of flower color and environmental affinity in either clade. We conclude that although abiotic stressors may play a role in the evolution of flower color within polymorphic species, we found no evidence that these processes lead to macroevolutionary patterns across monkeyflowers.
花青素色素赋予了被子植物许多鲜艳的粉色、紫色、红色和蓝色花朵颜色，并且在亲缘关系相近的物种内部和之间常常有所不同。虽然花青素众所周知会影响传粉者的吸引力，但它们也与对非生物胁迫因素的耐受性有关，如极端温度、降水减少和紫外线辐射。我们采用比较研究方法，测试了非生物变量是否能预测北美西部沟酸浆属植物（透骨草科）的花朵花青素含量。在两个多态物种中，我们发现非生物变量能够预测其地理分布范围内的花色。在[第一个物种]中，降水减少的种群中开粉色花（产生花青素）的个体频率更高。在[第二个物种]中，在降水减少、温度较低但紫外线辐射较少的较高海拔地区，开粉色花的个体频率更高。在宏观进化尺度上，在北美沟酸浆属植物的两次平行辐射中，有花花青素（粉色、紫色或红色花冠）的物种在[一种情况]下占据了降水减少的区域，但在[另一种情况]下并非如此。然而，在考虑系统发育相关性后，我们没有发现任何证据表明在任何一个进化枝中花色和环境亲和力存在共同进化。我们得出结论，虽然非生物胁迫因素可能在多态物种的花色进化中起作用，但我们没有发现证据表明这些过程会导致沟酸浆属植物的宏观进化模式。
