Small genomes in most mites (but not ticks)

Given their ecological and socioeconomic importance, it is not surprising that a number of mites (including ticks) have been the targets of recent genome sequencing projects. Less easily explained is why data on fundamental genetic parameters such as genome size (i.e. haploid DNA content) are greatly lacking for such a diverse and important group. Here, we compile the available genome size data for ticks and other mites, and add new estimates for another 20 species. We report a notable distinction in genome size between the comparatively larger genomes of ticks versus the (sometimes extremely) small genomes of non-tick mites. We also find a positive correlation between genome size and body size across mites, and explore some of the possible causes of the variability in genome size that exists among acarine species.

鉴于螨类（包括蜱虫）兼具生态与社会经济重要性，近年来诸多此类物种成为基因组测序项目的研究靶点，这一现象并不令人意外。但令人费解的是，为何这样一个多样性丰富且意义重大的类群，其基础遗传参数——如基因组大小（即单倍体DNA含量）——相关数据却极度匮乏。本研究汇编了已公开的蜱虫及其他螨类基因组大小数据，并新增了20个物种的基因组大小估算值。研究发现蜱虫与非蜱螨类的基因组大小存在显著差异：蜱虫的基因组相对较大，而非蜱螨类的基因组有时甚至极小。此外，我们还发现螨类的基因组大小与体型大小呈正相关，并探讨了蜱螨类物种间基因组大小存在变异的若干潜在成因。