Shikano Takahito, Laine Veronika N, Herczeg Gábor, Vilkki Johanna, Merilä Juha
Ecological Genetics Research Unit, Department of Biosciences, University of Helsinki, FI-00014, Helsinki, Finland.
G3 (Bethesda). 2013 Oct 3;3(10):1833-42. doi: 10.1534/g3.113.007237.
Teleost fish genomes are known to be evolving faster than those of other vertebrate taxa. Thus, fish are suited to address the extent to which the same vs. different genes are responsible for similar phenotypic changes in rapidly evolving genomes of evolutionary independent lineages. To gain insights into the genetic basis and evolutionary processes behind parallel phenotypic changes within and between species, we identified the genomic regions involved in pelvic reduction in Northern European ninespine sticklebacks (Pungitius pungitius) and compared them to those of North American ninespine and threespine sticklebacks (Gasterosteus aculeatus). To this end, we conducted quantitative trait locus (QTL) mapping using 283 F2 progeny from an interpopulation cross. Phenotypic analyses indicated that pelvic reduction is a recessive trait and is inherited in a simple Mendelian fashion. Significant QTL for pelvic spine and girdle lengths were identified in the region of the Pituitary homeobox transcription factor 1 (Pitx1) gene, also responsible for pelvic reduction in threespine sticklebacks. The fact that no QTL was observed in the region identified in the mapping study of North American ninespine sticklebacks suggests that an alternative QTL for pelvic reduction has emerged in this species within the past 1.6 million years after the split between Northern European and North American populations. In general, our study provides empirical support for the view that alternative genetic mechanisms that lead to similar phenotypes can evolve over short evolutionary time scales.
已知硬骨鱼基因组的进化速度比其他脊椎动物类群更快。因此，鱼类适合用于研究在进化上独立的谱系中，快速进化的基因组里，相同或不同基因对相似表型变化的影响程度。为了深入了解物种内部和物种之间平行表型变化背后的遗传基础和进化过程，我们确定了北欧九刺鱼（Pungitius pungitius）骨盆缩小所涉及的基因组区域，并将其与北美九刺鱼和三刺鱼（Gasterosteus aculeatus）的相应区域进行比较。为此，我们利用一个种群间杂交产生的283个F2后代进行了数量性状基因座（QTL）定位。表型分析表明，骨盆缩小是一种隐性性状，以简单的孟德尔方式遗传。在垂体同源框转录因子1（Pitx1）基因区域发现了与骨盆棘和骨盆带长度相关的显著QTL，该基因也与三刺鱼的骨盆缩小有关。在北美九刺鱼的定位研究中所确定的区域未观察到QTL，这一事实表明，在北欧和北美种群分化后的160万年里，该物种出现了导致骨盆缩小的另一个QTL。总的来说，我们的研究为以下观点提供了实证支持：导致相似表型的替代遗传机制可以在较短的进化时间尺度上进化。
