Department of Biology, University of North Carolina, Chapel Hill, NC 27599-3280, USA.
J Hered. 2012 Jan-Feb;103(1):103-14. doi: 10.1093/jhered/esr109. Epub 2011 Oct 19.
The outcome of hybridization can be impacted by environmental conditions, which themselves can contribute to reproductive isolation between taxa. In crosses of genetically divergent populations, hybridization can have both negative and positive impacts on fitness, the balance between which might be tipped by changes in the environment. Genetically divergent populations of the intertidal copepod Tigriopus californicus have been shown to differ in thermal tolerance at high temperatures along a latitudinal gradient. In this study, a series of crosses were made between pairs of genetically divergent populations of T. californicus, and the thermal tolerance of these hybrids was tested. In most cases, the first-generation hybrids had relatively high thermal tolerance and the second-generation hybrids were not generally reduced below the less-tolerant parental population for high temperature tolerance. This pattern contrasts with previous studies from crosses of genetically divergent populations of this copepod, which often shows hybrid breakdown in these second-generation hybrids for other measures of fitness. These results suggest that high temperature stress could either increase the positive impacts of hybridization or decrease the negative impacts of hybridization resulting in lowered hybrid breakdown in these population crosses.
杂交的结果可能会受到环境条件的影响，而这些环境条件本身也可能导致分类群之间的生殖隔离。在遗传上有差异的种群杂交中，杂交对适应性既有负面影响，也有正面影响，而环境的变化可能会打破这种平衡。在沿纬度梯度的高温条件下，潮间带桡足类动物加利福尼亚桡足类的遗传上有差异的种群在耐热性方面存在差异。在这项研究中，在加利福尼亚桡足类的两对遗传上有差异的种群之间进行了一系列杂交，并测试了这些杂种的耐热性。在大多数情况下，第一代杂种具有相对较高的耐热性，而第二代杂种在高温耐受性方面并不普遍低于较不耐药的亲种群。这种模式与以前对这种桡足类动物的遗传上有差异的种群进行的杂交研究形成对比，以前的研究表明，在这些第二代杂种中，其他适应性措施的杂种崩溃现象很常见。这些结果表明，高温胁迫可能会增加杂交的正面影响，或减少杂交的负面影响，从而降低这些种群杂交中的杂种崩溃现象。
