Department of Biology, University of Virginia, Charlottesville, VA 22904-4328, USA.
J Evol Biol. 2010 Aug;23(8):1720-31. doi: 10.1111/j.1420-9101.2010.02037.x. Epub 2010 Jul 5.
During biological invasions, multiple introductions can provide opportunities for admixture among genetically distinct lineages. Admixture is predicted to contribute to invasion success by directly increasing fitness through hybrid vigour or by enhancing evolutionary potential within populations. Here, we demonstrate genome-wide admixture during an invasion that substantially boosted fitness in the cosmopolitan weed, Silene vulgaris. We identified three divergent demes in the native European range that expanded from glacial refugia and experienced historical admixture in a well-known suture zone. During recent invasion of North America, multiple introductions created additional opportunities for admixture. In common garden experiments, recombinant genotypes from North America experienced a two-fold increase in fitness relative to nonrecombinants, whereas recombinant genotypes from Europe showed no lasting fitness benefits. This contrast implicates hybrid vigour behind the boost in fitness and supports the hypothesis that admixture can lead to fitness increases that may catapult invasion into a new range.
在生物入侵过程中，多次引种可以为遗传上不同谱系的混合提供机会。混合被预测通过杂种优势直接增加适应性，或者通过增强种群内的进化潜力，从而促进入侵成功。在这里，我们在一次入侵中证明了全基因组的混合，这大大提高了世界性杂草琉璃繁缕的适应性。我们在原生欧洲范围内发现了三个不同的群体，它们从冰川避难所扩张而来，并在一个著名的缝合区经历了历史上的混合。在最近对北美的入侵中，多次引种为混合创造了更多的机会。在共同花园实验中，来自北美的重组基因型相对于非重组基因型的适应性增加了一倍，而来自欧洲的重组基因型则没有持续的适应性优势。这种对比暗示了杂种优势是适应性提高的原因，并支持了这样一种假设，即混合可以导致适应性的提高，从而可能使入侵进入一个新的范围。
