Riss Simone, Arthofer Wolfgang, Steiner Florian M, Schlick-Steiner Birgit C, Pichler Maria, Stadler Peter, Stelzer Claus-Peter
Research Institute for Limnology, University of Innsbruck, Mondseestr. 9, 5310 Mondsee, Austria.
Institute of Ecology, University of Innsbruck, Technikerstr. 25, 6020 Innsbruck, Austria.
Hydrobiologia. 2017 Jul;796(1):59-75. doi: 10.1007/s10750-016-2872-x. Epub 2016 Jun 30.
Genome size in the rotifer , which belongs to the species complex, is greatly enlarged and extremely variable (205-407 Mbp). Such variation raises the question whether large genome size differences among individuals might cause reproductive barriers, which could trigger speciation within this group by restricting gene flow across populations. To test this hypothesis, we used clones from three geographic populations and conducted assays to quantify reproductive isolation among clones differing in genome size, and we examined the population structure of all three populations using amplified fragment length polymorphisms (AFLPs). AFLPs indicated that these populations were genetically separated, but we also found hints of natural gene flow. Clones from different populations with genome size differences of up to 1.7-fold could interbred successfully in the laboratory and give rise to viable, fertile 'hybrid' offspring. Genome sizes of these 'hybrids' were intermediate between those of their parents, and fitness in terms of male production, population growth, and egg development time was not negatively affected. Thus, we found no evidence for reproductive isolation or nascent speciation within . Instead, our results suggest that gene flow within this species can occur despite a remarkably large range of genome sizes.
属于该物种复合体的轮虫基因组大小大幅增大且极具变异性（205 - 407兆碱基对）。这种变异引发了一个问题，即个体间巨大的基因组大小差异是否会导致生殖隔离，而生殖隔离可能通过限制种群间的基因流动在该群体内引发物种形成。为了验证这一假设，我们使用了来自三个地理种群的克隆，并进行了实验来量化基因组大小不同的克隆之间的生殖隔离，同时我们使用扩增片段长度多态性（AFLP）分析了所有三个种群的种群结构。AFLP表明这些种群在基因上是隔离的，但我们也发现了自然基因流动的迹象。基因组大小差异高达1.7倍的不同种群的克隆在实验室中能够成功杂交，并产生有活力、可育的“杂交”后代。这些“杂交”后代的基因组大小介于其亲本之间，并且在雄性产生、种群增长和卵发育时间方面的适应性并未受到负面影响。因此，我们没有发现该物种内存在生殖隔离或新物种形成的证据。相反，我们的结果表明，尽管基因组大小范围差异极大，但该物种内仍可发生基因流动。
