Department of Environmental, Population, and Organismic Biology, Campus Box 334, University of Colorado,Boulder, Colorado 80309.
Am J Bot. 1998 Sep;85(9):1262-5.
Microgeographic allozyme variation was examined in pinyon pine, Pinus edulis, among five collection sites in Owl Canyon, Colorado. Relatively dry and moist sites were identified by associated plant communities and the sizes and densities of trees. Three moist sites and two dry sites were compared, and because all sites were within 600 m of one another, isolation by distance was not considered as a viable explanation of genetic differentiation between sites. Allelic frequencies at glycerate dehydrogenase (Gly) differed by 14% between moist and dry areas, and the pattern of microgeographic variation found here-allele 3 higher in frequency on dry sites-was consistent with previous studies of microgeographic variation in contrasting moist and dry sites. Trees within one of the dry sites were examined to test the hypothesis that stomata sizes and densities are heterogeneous among Gly genotypes. Heterozygotes had the longest and widest stomata; the stomatal area of heterozygotes was 28% greater than the stomatal area of homozygotes. Whereas the stomatal areas of the two homozygotes were similar, their shapes did not overlap when projected on a bivariate plot of length and width. These results suggest that stomatal shape may play a role in adapting pinyon to heterogeneity in soil moisture.
在科罗拉多州 Owl Canyon 的五个采集点，对辐射松（Pinus edulis）的微地理等位酶变异进行了研究。通过相关植物群落以及树木的大小和密度确定了相对干燥和湿润的地点。比较了三个湿润地点和两个干燥地点，由于所有地点彼此相距不到 600 米，因此距离隔离不能作为解释地点间遗传分化的合理依据。甘油醛脱氢酶（Gly）的等位基因频率在湿润和干燥地区相差 14%，这里发现的微地理变异模式-干燥地区等位基因 3 的频率较高-与先前对湿润和干燥地区对比的微地理变异研究一致。对一个干燥地点的树木进行了检查，以检验气孔大小和密度在 Gly 基因型之间存在异质性的假设。杂合体具有最长和最宽的气孔；杂合体的气孔面积比纯合体大 28%。虽然两个纯合体的气孔面积相似，但当在长度和宽度的双变量图上投影时，它们的形状没有重叠。这些结果表明，气孔形状可能在适应辐射松对土壤水分异质性方面发挥作用。
