Aggarwal Dau Dayal, Rashkovetsky Eugenia, Michalak Pawel, Cohen Irit, Ronin Yefim, Zhou Dan, Haddad Gabriel G, Korol Abraham B
Institute of Evolution, University of Haifa, Haifa, 3498838, Israel.
Virginia Bioinformatics Institute, Virginia Tech, Washington Street, MC 0477, Blacksburg, VA, 24061-0477, USA.
BMC Biol. 2015 Nov 27;13:101. doi: 10.1186/s12915-015-0206-5.
Population genetics predicts that tight linkage between new and/or pre-existing beneficial and deleterious alleles should decrease the efficiency of natural selection in finite populations. By decoupling beneficial and deleterious alleles and facilitating the combination of beneficial alleles, recombination accelerates the formation of high-fitness genotypes. This may impose indirect selection for increased recombination. Despite the progress in theoretical understanding, interplay between recombination and selection remains a controversial issue in evolutionary biology. Even less satisfactory is the situation with crossover interference, which is a deviation of double-crossover frequency in a pair of adjacent intervals from the product of recombination rates in the two intervals expected on the assumption of crossover independence. Here, we report substantial changes in recombination and interference in three long-term directional selection experiments with Drosophila melanogaster: for desiccation (~50 generations), hypoxia, and hyperoxia tolerance (>200 generations each).
For all three experiments, we found a high interval-specific increase of recombination frequencies in selection lines (up to 40-50% per interval) compared to the control lines. We also discovered a profound effect of selection on interference as expressed by an increased frequency of double crossovers in selection lines. Our results show that changes in interference are not necessarily coupled with increased recombination.
Our results support the theoretical predictions that adaptation to a new environment can promote evolution toward higher recombination. Moreover, this is the first evidence of selection for different recombination-unrelated traits potentially leading, not only to evolution toward increased crossover rates, but also to changes in crossover interference, one of the fundamental features of recombination.
群体遗传学预测，在有限群体中，新的和/或先前存在的有益等位基因与有害等位基因之间的紧密连锁会降低自然选择的效率。通过解开有益等位基因和有害等位基因的连锁，并促进有益等位基因的组合，重组加速了高适应性基因型的形成。这可能会对增加重组产生间接选择作用。尽管在理论理解上取得了进展，但重组与选择之间的相互作用在进化生物学中仍然是一个有争议的问题。关于交叉干涉的情况更不尽人意，交叉干涉是指一对相邻区间内的双交换频率偏离了在交叉独立假设下预期的两个区间重组率的乘积。在这里，我们报告了在黑腹果蝇的三个长期定向选择实验中重组和干涉的显著变化：针对干燥耐受性（约50代）、低氧耐受性和高氧耐受性（每个超过200代）。
对于所有这三个实验，我们发现与对照品系相比，选择品系中重组频率在区间特异性上有高度增加（每个区间高达40 - 50%）。我们还发现选择对干涉有深远影响，表现为选择品系中双交换频率增加。我们的结果表明，干涉的变化不一定与重组增加相关联。
我们的结果支持了理论预测，即适应新环境可以促进向更高重组率的进化。此外，这是首次有证据表明对不同的与重组无关的性状进行选择，不仅可能导致向更高交叉率的进化，还可能导致交叉干涉的变化，而交叉干涉是重组的基本特征之一。
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