The biological meaning of low complexity regions in the proteins of Plasmodium species is a topic of discussion in evolutionary biology. There is a debate between selectionists and neutralists, who either attribute or do not attribute an effect of low-complexity regions on the fitness of these parasites, respectively. In this work, we comparatively study 22 Plasmodium species to understand whether their low complexity regions undergo a neutral or, rather, a selective and species-dependent evolution. The focus is on the connection between the codon repertoire of the genetic coding sequences and the occurrence of low complexity regions in the corresponding proteins. The first part of the work concerns the correlation between the length of plasmodial proteins and their propensity at embedding low complexity regions. Relative synonymous codon usage, entropy, and other indicators reveal that the incidence of low complexity regions and their codon bias is species-specific and subject to selective evolutionary pressure. We also observed that protein length, a relaxed selective pressure, and a broad repertoire of codons in proteins, are strongly correlated with the occurrence of low complexity regions. Overall, it seems plausible that the codon bias of low-complexity regions contributes to functional innovation and codon bias enhancement of proteins on which Plasmodium species rest as successful evolutionary parasites.

疟原虫物种蛋白质中低复杂性区域的生物学意义是进化生物学中的一个讨论话题。选择主义者和中立主义者之间存在争论，他们分别归因于或不归因于低复杂性区域对这些寄生虫的适应度的影响。在这项工作中，我们比较研究了 22疟原虫物种以了解它们的低复杂性区域是否经历中性进化，或者更确切地说，是选择性和依赖物种的进化。重点是遗传编码序列的密码子库与相应蛋白质中低复杂性区域的出现之间的联系。工作的第一部分涉及疟原虫蛋白的长度与其嵌入低复杂性区域的倾向之间的相关性。相对同义密码子使用、熵和其他指标表明，低复杂性区域的发生率及其密码子偏向具有物种特异性，并受到选择性进化压力的影响。我们还观察到蛋白质长度、放松的选择压力和蛋白质中广泛的密码子库，与低复杂性区域的出现密切相关。总的来说，疟原虫物种作为成功的进化寄生虫而存在。