Zivanovic G, Arenas C, Mestres F
Department of Genetics, Institute for Biological Research "Sinisa Stankovic", University of Belgrade, Belgrade, Serbia.
Departament d'Estadística, Universitat de Barcelona, Barcelona, Spain.
J Evol Biol. 2016 Mar;29(3):657-64. doi: 10.1111/jeb.12800. Epub 2015 Dec 29.
It is generally accepted that chromosomal inversions have been key elements in adaptation and speciation processes. In this context, Drosophila subobscura has been, and still is, an excellent model species due to its rich chromosomal polymorphism. In this species, many analyses from natural populations have demonstrated the adaptive potential of individual inversions (and their overlapped combinations, the so-called arrangements). However, little information is available on the evolutionary role of combinations generated by inversions located in homologous and nonhomologous chromosomes. The aim of this research was to ascertain whether these combinations are also a target for natural selection. For this objective, we have studied the inversion composition of homologous and nonhomologous chromosomes from a D. subobscura sample collected in a well-studied population, Mount Avala (Serbia). No significant deviation from H-W expectations was detected, and when comparing particular karyotypic combinations, likelihood ratios close to 1 were obtained. Thus, it seems that for each pair of homologous chromosomes inversions no deviation from randomness was detected. Finally, no linkage disequilibrium was observed between inversions located in different chromosomes of the karyotype. For all these reasons, it can be assumed that, at the cytological level, the individual inversions rather than their combinations in different chromosomes are the main target of selection.
一般认为，染色体倒位是适应和物种形成过程中的关键因素。在此背景下，由于其丰富的染色体多态性，暗果蝇一直是，并且仍然是一个优秀的模式物种。在这个物种中，许多对自然种群的分析已经证明了单个倒位（及其重叠组合，即所谓的排列）的适应潜力。然而，关于同源染色体和非同源染色体上的倒位所产生的组合的进化作用，我们所知甚少。本研究的目的是确定这些组合是否也是自然选择的目标。为了实现这一目标，我们研究了从一个经过充分研究的种群——阿瓦拉山（塞尔维亚）采集的暗果蝇样本中同源染色体和非同源染色体的倒位组成。未检测到与哈迪-温伯格预期的显著偏差，并且在比较特定的核型组合时，获得了接近1的似然比。因此，似乎对于每对同源染色体倒位，未检测到偏离随机性的情况。最后，在核型的不同染色体上的倒位之间未观察到连锁不平衡。基于所有这些原因，可以假定，在细胞学水平上，单个倒位而非它们在不同染色体上的组合是选择的主要目标。
