Institute of Evolutionary Biology (CSIC-Universitat Pompeu Fabra), Barcelona, Spain.
University of Seville, Seville, Spain.
Mol Phylogenet Evol. 2021 Jun;159:107087. doi: 10.1016/j.ympev.2021.107087. Epub 2021 Feb 2.
The long-term geological stability of aquatic habitats has been demonstrated to be a determinant in the evolution of macroinvertebrate fauna, with species in running (lotic) waters having lower dispersal abilities, smaller ranges and higher gene flow between populations than species in standing (lentic) environments. Lotic species have been hypothesized to be more specialised, but the diversification dynamics of both habitat types have not been studied in detail. Using a speciose lineage of water beetles we test here whether diversification rates are related to the habitat preference of the species and its consequences on turnover, which we expect to be higher for lotic taxa. Moreover, we tested whether life in lotic environments is acting as an evolutionary dead-end as it is considered an ecological specialisation. We built a comprehensive molecular phylogeny with 473 terminals representing 421 of the 689 known species of the tribe Hydroporini (Coleoptera, Dytiscidae), using a combination of sequences from four mitochondrial and two nuclear genes plus 69 mitogenomes obtained with NGS. We found a general pattern of gradual acceleration of diversification rate with time, with 2-3 significant diversification shifts. However, habitat is not the main factor driving diversification in Hydroporini based on SecSSE analyses. The most recent common ancestor of Hydroporini was reconstructed as a lotic species, with multiple shifts to lentic environments. Most frequent transitions were estimated from lentic and lotic habitats to the category "both", followed by transitions from lotic to lentic and lentic to lotic respectively, although with very similar rates. Contrary to expectations, we found little evidence for differences in diversification dynamics between habitats, with lotic environments clearly not acting as evolutionary dead-ends in Hydroporini.
水生栖息地的长期地质稳定性已被证明是宏动物区系进化的决定因素，与静水（静止）环境中的物种相比，流水（流动）水域中的物种扩散能力较低，分布范围较小，种群间基因流动较高。流动物种被假设为更特化，但两种生境类型的多样化动态尚未得到详细研究。在这里，我们使用一个多样化的水生甲虫谱系来检验物种对栖息地的偏好与物种周转率之间的关系，我们预计流动分类群的周转率会更高。此外，我们还测试了流水环境是否作为进化的死胡同，因为它被认为是一种生态特化。我们构建了一个综合的分子系统发育树，共有 473 个末端，代表了 Hydroporini 科（鞘翅目，水龟科）689 种已知物种中的 421 种，使用了来自四个线粒体和两个核基因的序列以及 69 个通过 NGS 获得的线粒体基因组。我们发现了一个多样化率随时间逐渐加速的一般模式，有 2-3 个显著的多样化转变。然而，基于 SecSSE 分析，栖息地并不是 Hydroporini 多样化的主要因素。Hydroporini 的最近共同祖先被重建为流水物种，有多次向静水环境的转变。估计最频繁的转变是从静水和流水生境到“两者兼有”的类别，其次是从流水生境到静水生境和从静水生境到流水生境的转变，尽管转变速度非常相似。与预期相反，我们几乎没有发现栖息地之间多样化动态存在差异的证据，流水环境在 Hydroporini 中显然不是进化的死胡同。
