Aldridge George
Rocky Mountain Biological Laboratory, PO Box 519, Crested Butte, CO 81224, USA.
New Phytol. 2005 Jul;167(1):279-88. doi: 10.1111/j.1469-8137.2005.01413.x.
Rates of hybridization vary among angiosperm taxa. Among-taxon variation in hybridization rate has been used to compare the importance of pre- and post-zygotic reproductive isolating mechanisms. Variation in rates of hybridization within a single-species pair would suggest that local conditions also affect reproductive isolation within a single taxonomic context. In this study, contact sites of Ipomopsis aggregata-Ipomopsis tenuituba were surveyed for variation in frequency of hybrids, and spatial structure. Floral morphology was used to identify parent species and hybrids in seven contact sites in the western Rocky Mountains, USA. Contact sites varied widely in elevational range, the degree to which morphological variation was clinal rather than mosaic and the frequency of hybrids. Two sites provided a strong contrast between a clinal, unimodal site and a mosaic, bimodal site. This natural variation among contact sites of the same species pair provides an opportunity to assess the effect of local ecological conditions and spatial structure of parent populations on reproductive isolation, while controlling for between-taxon variation.
杂交速率在被子植物类群中各不相同。类群间杂交速率的差异已被用于比较合子前和合子后生殖隔离机制的重要性。单一物种对中杂交速率的差异表明，局部条件也会在单一分类背景下影响生殖隔离。在本研究中，对聚合矮牵牛 - 细管矮牵牛的接触位点进行了调查，以了解杂种频率和空间结构的变化。利用花的形态学特征在美国落基山脉西部的七个接触位点识别亲本物种和杂种。接触位点在海拔范围、形态变异是渐变而非镶嵌的程度以及杂种频率方面差异很大。有两个位点在渐变单峰位点和镶嵌双峰位点之间形成了强烈对比。同一物种对接触位点之间的这种自然变异提供了一个机会，可在控制类群间变异的同时，评估局部生态条件和亲本种群空间结构对生殖隔离的影响。
