Grossenbacher Dena L, Lo Magdalene S, Waddington Molly E, O'Dell Ryan, Kay Kathleen M
Biological Sciences Department, California Polytechnic State University, San Luis Obispo, 93407, CA, USA.
Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, Santa Cruz, 95060, CA, USA.
Am J Bot. 2025 Mar 13:e70018. doi: 10.1002/ajb2.70018.
Floral pigments such as anthocyanins are well known to influence pollinator attraction, yet they also confer tolerance to abiotic stressors such as harsh soils, extreme temperatures, low precipitation, and UV radiation. In such cases, environmental variation in abiotic stressors over space or time could lead to the maintenance of flower color variation within species. Under this scenario, flower color in natural populations should covary with environmental stressors.
Using a comparative approach, we tested whether abiotic variables predict flower color in Leptosiphon parviflorus, a species with pink and white flower color morphs. We conducted in-depth field studies to assess morph frequency, soil chemistry, and climate. We then employed community scientist-powered iNaturalist observations to examine patterns across even larger spatial scales.
Across 21 field sites, L. parviflorus had a higher frequency of pink morphs in sites with serpentine soil, higher average annual temperatures, and higher average climatic water deficit (a proxy for drought stress). iNaturalist observations supported this finding-the probability of flowers being pink is greater in locations with serpentine-derived soil, especially when the local average UV radiation and climatic water deficit are higher.
Spatial variation in abiotic stressors may contribute to the maintenance of flower color variation across the geographic range of L. parviflorus. Future studies will examine mechanisms by which flower color affects stress tolerance and will assess whether fitness trade-offs in contrasting habitats across the range are associated with flower color.
众所周知，花青素等花卉色素会影响传粉者的吸引力，但它们也能使植物耐受非生物胁迫，如贫瘠土壤、极端温度、低降水量和紫外线辐射。在这种情况下，非生物胁迫在空间或时间上的环境变化可能导致物种内花色变异的维持。在这种情况下，自然种群中的花色应该与环境胁迫相关。
我们采用比较研究方法，测试非生物变量是否能预测小花细裂叶芹（Leptosiphon parviflorus）的花色，该物种有粉色和白色两种花色形态。我们进行了深入的实地研究，以评估形态频率、土壤化学性质和气候。然后，我们利用由社区科学家提供支持的iNaturalist观测数据，来研究更大空间尺度上的模式。
在21个实地研究地点中，小花细裂叶芹在蛇纹岩土、年平均温度较高以及平均气候水分亏缺较大（干旱胁迫的一个指标）的地点，粉色形态的频率更高。iNaturalist观测数据支持了这一发现——在源自蛇纹岩的土壤地区，花朵呈现粉色的概率更大，尤其是当当地平均紫外线辐射和气候水分亏缺较高时。
非生物胁迫的空间变异可能有助于维持小花细裂叶芹地理分布范围内的花色变异。未来的研究将探讨花色影响胁迫耐受性的机制，并评估该分布范围内不同生境中的适合度权衡是否与花色有关。
