Weller S G, Sakai A K, Gray T, Weber J J, Tsyusko O V, Domínguez C A, Fornoni J, Molina-Freaner F E
Department of Ecology and Evolutionary Biology, University of California, Irvine, CA, USA.
Department of Plant and Soil Sciences, University of Kentucky, Lexington, KY, USA.
Plant Biol (Stuttg). 2016 Jan;18(1):104-10. doi: 10.1111/plb.12340. Epub 2015 May 27.
The heterostylous reproductive system of Oxalis alpina in the Galiuro Mts. of Arizona was investigated using field surveys, controlled crosses in the greenhouse and measurements of reproductive morphs. Although populations in the Pinaleño Mts. to the immediate east and in the Santa Catalina Mts. to the immediate west have derived distylous reproductive systems, tristyly, the ancestral reproductive system in O. alpina, has been retained in the Galiuro Mts.
Tristylous incompatibility relationships in the Galiuro population are modified from the ancestral condition, with significant loss of incompatibility differentiation between stamen whorls of both short- and long-styled morphs. Morphological adjustments of anther positions in the Galiuro population of O. alpina match those expected in light of incompatibility modification, with divergence of the mid-level anthers away from the position of the mid stigmas of the mid-styled morph. The occurrence of tristyly in an area of Arizona where distyly is found in adjacent mountain ranges is particularly remarkable, and indicates both the isolation of populations restricted to the upper elevations of these mountain ranges and variation in the tempo of evolution over short geographic distances.
利用实地调查、温室中的控制杂交以及对繁殖形态的测量，对亚利桑那州加柳罗山脉的高山酢浆草的异型花柱繁殖系统进行了研究。尽管紧邻东部的皮纳莱诺山脉和紧邻西部的圣卡塔利娜山脉的种群具有衍生的二型花柱繁殖系统，但三型花柱，即高山酢浆草的祖先繁殖系统，在加柳罗山脉中得以保留。
加柳罗种群中的三型花柱不亲和关系与祖先状态有所不同，短花柱和长花柱形态的雄蕊轮之间的不亲和分化显著丧失。高山酢浆草加柳罗种群中花药位置的形态调整与根据不亲和性改变所预期的情况相符，中层花药偏离中型花柱形态的中柱头位置。在亚利桑那州一个地区出现三型花柱，而相邻山脉中存在二型花柱，这一现象尤为显著，表明局限于这些山脉较高海拔的种群具有隔离性，且在短地理距离内进化速度存在差异。
