Institute of Biological, Environmental and Rural Sciences, Aberystwyth University, Plas Gogerddan, Aberystwyth, Ceredigion, SY23 3EB, UK.
Mol Ecol. 2012 Oct;21(19):4669-71. doi: 10.1111/j.1365-294X.2012.05720.x.
Human activity and climate change are increasingly driving species, which were once separate together, leading to the potential for gene flow. Hybridization between diverged species brings together two genomes which have evolved to meet different adaptive requirements. The unique combination of these traits in a hybrid may be beneficial or maladaptive, but either way it results in increased phenotypic variation. A percentage of hybrid individuals may, therefore, find themselves able to exploit environmental niches which their progenitors cannot, leading to invasive hybrid swarms becoming established in new habitats. Previous research into hybrids, most famously that of Loren Rieseberg and co-workers (Rieseberg et al. 1999, 2003) in sunflowers, demonstrated that hybridization can give rise to transgressive segregation of adaptive traits, wherein the combination of favourable alleles from both parents in hybrids can enable them to outperform either. However, the question still remains as to how much of the competitive ability of hybrids is a direct result of admixture and how much is the result of selection after the fact. In this issue of Molecular Ecology, (Czypionka et al. 2012) describe their study of transcriptional changes resulting from hybridization in a fish hybrid termed invasive sculpins (Cottus). Using gene expression microarray assays, they compare gene expression in both wild and lab-reared invasive hybrids to the progenitor species and experimentally produced F(2) hybrids. They demonstrate that whilst hybridization alone does result in higher variance in gene expression (some of which is transgressive), many of the transgressive changes distinguishing the invasives appear to have come about subsequent to the initial natural hybridization event. They speculate that initial success of the hybrids in their new habitat is facilitated by hybridization, but that optimization of the invasive phenotype and removal of maladaptive traits rapidly reduces the variation in gene expression seen in early hybrids.
人类活动和气候变化正日益促使原本分开的物种聚集在一起，从而导致基因流动的可能性增加。分化物种之间的杂交将两个已经进化以适应不同适应性要求的基因组结合在一起。这些性状在杂种中的独特组合可能是有益的，也可能是适应不良的，但无论哪种方式，都会导致表型变异增加。因此，一部分杂种个体可能会发现自己能够利用其祖先无法利用的环境小生境，从而导致入侵杂种群体在新栖息地中建立起来。以前对杂种的研究，最著名的是 Loren Rieseberg 及其同事（Rieseberg 等人，1999 年，2003 年）在向日葵中的研究表明，杂交可以产生适应性性状的过度分离，其中来自父母双方的有利等位基因在杂种中的组合可以使它们表现得更好。然而，问题仍然是杂种的竞争能力有多少是直接由于混合的结果，有多少是事实选择的结果。在本期《分子生态学》中，（Czypionka 等人，2012 年）描述了他们对一种名为入侵棘鱼（Cottus）的鱼类杂种杂交引起的转录变化的研究。他们使用基因表达微阵列分析，比较了野生和实验室饲养的入侵杂种以及亲本物种和实验产生的 F2 杂种的基因表达。他们表明，尽管单独的杂交确实会导致基因表达的更高方差（其中一些是过度的），但区分入侵物种的许多过度变化似乎是在最初的自然杂交事件之后发生的。他们推测，杂种在新栖息地中的最初成功是由杂交促成的，但入侵表型的优化和适应不良性状的去除迅速降低了早期杂种中观察到的基因表达变化。
