Santos Neto J F, Soares G B, Domingues M V
Laboratório de Sistemática e Coevolução, Universidade Federal do Pará, Campus Universitário de Bragança, Instituto de Estudos Costeiros; Travessa Leandro Ribeiro, s/n, bairro Aldeia, 68600-000, Bragança, Pará, Brazil.
Programa de Pós-Graduação em Biologia Ambiental da Universidade Federal do Pará.
J Helminthol. 2025 Aug 29;99:e97. doi: 10.1017/S0022149X25100643.
Historical reconstruction studies are important for understanding the evolutionary mechanisms associated with different parasite-host systems. Platyhelminths of the classes Monopisthocotyla and Polyopisthocotyla (formerly Monogenoidea or Monogenea) have proven to be excellent models for historical reconstruction studies due to their exceptional parasite specificity, suggesting that cospeciation events are the main pattern observed in these parasite-host systems (i.e., codivergence). However, recent studies indicate that not only cospeciation but also duplication, host-switch, and loss (extinction) events are necessary to explain the historical association patterns between monopisthocotylan lineages and their hosts. In the present study, we describe four new species of parasitizing the gills of Characiformes and Gymnotiformes hosts from the coastal drainages of the eastern Brazilian Amazon. We also used a cophylogenetic approach to investigate the coevolutionary relationships between species and their characiform hosts to determine which coevolutionary events are acting to diversify the parasites. To achieve our goal, we used Jane to estimate coevolutionary scenarios and PACo to assess the cophylogenetic signal and phylogenetic congruence between parasite and host phylogenies. The comparison between the parasite phylogeny, based on partial sequences of the 28S rDNA gene, and the host phylogeny, inferred from concatenated partial sequences of the RAG1, RAG2, Cytb, and COI genes, revealed a high degree of topological congruence between them. Our results indicate a mixed evolutionary scenario, where cospeciation played an important role but was accompanied by significant loss events, failure to diverge and host-switch, suggesting that the diversification of in Characiformes did not occur in a restricted way but with episodes of adaptation and possible colonization of new hosts over time.
历史重建研究对于理解与不同寄生虫-宿主系统相关的进化机制至关重要。单殖吸虫纲和多殖吸虫纲（以前的单殖亚纲或单殖吸虫）的扁形虫已被证明是历史重建研究的优秀模型，因为它们具有特殊的寄生虫特异性，这表明共物种形成事件是这些寄生虫-宿主系统中观察到的主要模式（即协同分歧）。然而，最近的研究表明，不仅共物种形成，而且复制、宿主转换和丢失（灭绝）事件对于解释单殖吸虫谱系与其宿主之间的历史关联模式也是必要的。在本研究中，我们描述了寄生于巴西东部亚马逊沿海排水系统中脂鲤目和电鳗目宿主鳃上的四种新物种。我们还使用了共系统发育方法来研究这些物种与其脂鲤目宿主之间的协同进化关系，以确定哪些协同进化事件正在使寄生虫多样化。为了实现我们的目标，我们使用Jane来估计协同进化情景，并使用PACo来评估寄生虫和宿主系统发育之间的共系统发育信号和系统发育一致性。基于28S rDNA基因部分序列的寄生虫系统发育与从RAG1、RAG2、Cytb和COI基因的串联部分序列推断出的宿主系统发育之间的比较，揭示了它们之间高度的拓扑一致性。我们的结果表明了一种混合进化情景，其中共物种形成起到了重要作用，但同时伴随着大量的丢失事件、未能分化和宿主转换，这表明脂鲤目中这些寄生虫的多样化并非以受限的方式发生，而是随着时间的推移伴随着适应和可能的新宿主定殖事件。
