A steep cline in flowering time for Brassica rapa in southern California:: Population-level variation in the field and the greenhouse
A steep cline in flowering time for Brassica rapa in southern California:: Population-level variation in the field and the greenhouse
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DOI：
10.1086/497648
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发表时间：
2006-01-01
影响因子：
2.3
通讯作者：
Weis, AE
中科院分区：
文献类型：
--
作者：
Franke, DM;Ellis, AG;Weis, AE
我们研究了南加州一系列占据4公里长的城市绿地的油菜种群在开花时间上的克隆变异。对两个种群的田间研究表明，在1998-1999季节，当厄尔尼诺事件使降雨量大大超过正常水平时，今年冬季种群的平均开花日期相差达3wk。在1999-2000年，由于干旱推迟了生长季的开始，种群差异程度缩小。在这两年，占据较干燥地点的种群开花较早。两个地点分别估计的适合度函数表明，干旱地点的早花选择是定向选择，潮湿地点的选择是稳定成分。在不同的光周期条件下，利用沿坡地的其他种群进行的温室试验表明，当在共同环境中生长时，旱地植物比湿地植物开花早。这表明了种群间变异的遗传基础。开花物候的种群间变异程度被长光周期压缩。
We examined clinal variation in flowering time in a series of Brassica rapa populations occupying a 4-km-long urban greenbelt in southern California. Field studies on two populations showed that mean flowering date for populations of this winter annual differed by up to 3 wk during the 1998 - 1999 season, when an El Nino event elevated precipitation well beyond normal levels. The degree of population difference was compressed in 1999 - 2000, when drought delayed onset of the growing season. In both years, the population occupying the drier site flowered earlier. Fitness functions, estimated separately for the two sites, indicated directional selection for early flowering in the dry site and a stabilizing component to selection at the wet site. Greenhouse experiments using other populations along the cline and conducted under different photoperiod conditions showed that when grown in a common environment, dry-site plants flower earlier than wet-site plants. This indicates a genetic basis for between-population variation. The degree of among-population variation in flowering phenology is compressed by long photoperiods.