Nagy Eric S, Rice Kevin J
Section of Evolution and Ecology, and Center for Population Biology, University of California, Davis, California, 95616.
Department of Agronomy and Range Science, University of California, Davis, California, 95616.
Evolution. 1997 Aug;51(4):1079-1089. doi: 10.1111/j.1558-5646.1997.tb03955.x.
Plant populations often adapt to local environmental conditions. Here we demonstrate local adaptation in two subspecies of the California native annual Gilia capitata using standard reciprocal transplant techniques in two sites (coastal and inland) over three consecutive years. Subspecies performance in each site was measured in four ways: probability of seedling emergence, early vegetative size (length of longest leaf), probability of flowering, and total number of inflorescences produced per plant. Analysis of three of the four variables demonstrated local adaptation through site-by-subspecies interactions in which natives outperformed immigrants. The disparity between natives and immigrants in their probability of emergence and probability of flowering was greater at the coastal site than at the inland site. Treated in isolation, these two fitness components suggest that migration from the coast to the inland site may be less restricted by selection than migration in the opposite direction. Two measurements of individual size (leaf length and number of inflorescences), suggest (though not strongly) that immigrants may be subject to weaker selection at the coastal site than at the inland site. A standard cohort life table is used to compare replacement rates (R ) for each subspecies at each site. Comparisons of R s suggest that immigrants are under a severe demographic disadvantage at the coastal site, but only a small disadvantage at the inland site. The results point out the importance of integrating over several fitness components when documenting the magnitude of local adaptation.
植物种群常常会适应当地的环境条件。在这里，我们通过连续三年在两个地点（沿海和内陆）运用标准的 reciprocal transplant 技术，展示了加利福尼亚本土一年生植物 Gilia capitata 的两个亚种的局部适应性。每个地点的亚种表现通过四种方式来衡量：幼苗出土概率、早期营养体大小（最长叶片长度）、开花概率以及每株植物产生的总花序数。对四个变量中的三个进行分析，通过地点 - 亚种相互作用证明了局部适应性，其中本地种的表现优于外来种。沿海地点本地种和外来种在出土概率和开花概率上的差异比内陆地点更大。单独来看，这两个适合度成分表明，从沿海向内陆地点的迁移可能比相反方向的迁移受选择的限制更小。个体大小的两项测量（叶片长度和花序数）表明（尽管不太明显），外来种在沿海地点可能比在内陆地点受到的选择压力更小。使用标准的同期群生命表来比较每个地点每个亚种的替代率（R）。R 的比较表明，外来种在沿海地点处于严重的种群统计学劣势，但在内陆地点仅处于较小的劣势。结果指出，在记录局部适应性的程度时，综合考虑多个适合度成分的重要性。
