arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1506.05352q-bio.PEq-bio.BM
收藏

基因型-表型图谱的结构强烈地限制了非编码RNA的进化

The structure of the genotype-phenotype map strongly constrains the evolution of non-coding RNA

Kamaludin Dingle, Steffen Schaper, Ard A. Louis

摘要:

中性突变的流行意味着生物系统通常具有比表型多得多的基因型。但是基因型在表型上的分布方式能决定进化的结果吗?提出这样的问题是困难的,因为基因型的数量可能是超级天文数字。通过解决RNA二级结构的基因型-表型(GP)地图系统的长度为$L=126$核苷酸(其中所有可能的RNA链的集合将重量超过可见宇宙的质量),我们表明,GP地图强烈约束非编码RNA(ncRNA)的进化。基因型上的简单随机抽样预测了性质的分布,例如在天然存在的ncRNA中发现的突变稳健性或每个二级结构的茎数,其准确性令人惊讶。由于我们忽略了自然选择,这种与图谱惊人的密切对应表明,尽管遗传空间巨大,但允许功能的结构很容易被发现。映射是非常有偏见的:大多数基因型映射到所有生物学上可能的结构的形态空间的指数小部分。这种强约束为锤头状核酶等结构的趋同进化提供了非适应性解释。这些结果提出了一个特别明确的例子,在变化的到来强烈塑造进化的结果,并可能与迈尔的近因和最终原因在进化生物学的区别偏见。

英文摘要:

The prevalence of neutral mutations implies that biological systems typically have many more genotypes than phenotypes. But can the way that genotypes are distributed over phenotypes determine evolutionary outcomes? Answering such questions is difficult because the number of genotypes can be hyper-astronomically large. By solving the genotype-phenotype (GP) map for RNA secondary structure for systems up to length $L=126$ nucleotides (where the set of all possible RNA strands would weigh more than the mass of the visible universe) we show that the GP map strongly constrains the evolution of non-coding RNA (ncRNA). Simple random sampling over genotypes predicts the distribution of properties such as the mutational robustness or the number of stems per secondary structure found in naturally occurring ncRNA with surprising accuracy. Since we ignore natural selection, this strikingly close correspondence with the mapping suggests that structures allowing for functionality are easily discovered, despite the enormous size of the genetic spaces. The mapping is extremely biased: the majority of genotypes map to an exponentially small portion of the morphospace of all biophysically possible structures. Such strong constraints provide a non-adaptive explanation for the convergent evolution of structures such as the hammerhead ribozyme. These results presents a particularly clear example of bias in the arrival of variation strongly shaping evolutionary outcomes and may be relevant to Mayr's distinction between proximate and ultimate causes in evolutionary biology.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑