Díaz-Sánchez Sandra, Hernández-Triana Luis M, Labruna Marcelo B, Merino Octavio, Mosqueda Juan, Nava Santiago, Szabó Matias, Tarragona Evelina, Venzal José M, de la Fuente José, Estrada-Peña Agustín
SaBio, Instituto de Investigación en Recursos Cinegéticos IREC-CSIC-UCLM-JCCM, Ronda de Toledo s/n, 13005 Ciudad Real, Spain.
Animal and Plant Health Agency, Virology Department, Surrey KT15 3NB, UK.
Pathogens. 2023 Nov 13;12(11):1344. doi: 10.3390/pathogens12111344.
This study addresses the variability of the mitochondrial cytochrome oxidase subunit I () and (), and nuclear internal transcriber spacer () genes in a set of field-collected samples of the cattle tick, (Canestrini, 1888), and in geo-referenced sequences obtained from GenBank. Since the tick is currently considered to be a complex of cryptic taxa in several regions of the world, the main aims of the study are (i) to provide evidence of the clades of the tick present in the Neotropics, (ii) to explore if there is an effect of climate traits on the divergence rates of the target genes, and (iii) to check for a relationship between geographical and genetic distance among populations (the closest, the most similar, meaning for slow spread). We included published sequences of (Nearctic, Afrotropical, and Mediterranean) and (Afrotropical, Indomalayan) to fully characterize the Neotropical populations (total: 74 , 44 , and 49 sequences included in the analysis). Only the clade A of spread in the Nearctic-Neotropics. Both the K and Lambda's statistics, two measures of phylogenetic signal, support low divergence rates of the tested genes in populations of in the Neotropics. These tests demonstrate that genetic diversity of the continental populations does not correlate either with the geographic distance among samples or with environmental variables. The low variability of these genes may be due to a combination of factors like (i) the recent introduction of the tick in the Neotropics, (ii) a large, effective, and fast exchange of populations, and (iii) a low effect of climate on the evolution rates of the target genes. These results have implications for the ecological studies and control of cattle tick infestations.
本研究探讨了线粒体细胞色素氧化酶亚基I（COI）和细胞色素b（CYTB）以及核糖体DNA内转录间隔区1（ITS1）基因在一组野外采集的牛蜱样本（血红扇头蜱，Canestrini，1888）中的变异性，以及从GenBank获得的地理定位序列中的变异性。由于这种蜱在世界上的几个地区目前被认为是一个隐存分类群复合体，本研究的主要目的是：（i）提供新热带地区存在的蜱类进化枝的证据；（ii）探究气候特征是否对目标基因的分歧率有影响；（iii）检查种群之间地理距离与遗传距离之间的关系（距离越近，相似度越高，意味着传播速度越慢）。我们纳入了已发表的美洲地区、非洲热带地区和地中海地区的COI序列，以及非洲热带地区和东洋界的CYTB序列，以全面描述新热带地区的种群（分析中总共包括74条COI序列、44条CYTB序列和49条ITS1序列）。只有COI的进化枝A在近北极 - 新热带地区传播。系统发育信号的两种度量方法，即K统计量和拉姆达统计量，均支持新热带地区血红扇头蜱种群中测试基因的低分歧率。这些测试表明，大陆种群的遗传多样性与样本之间的地理距离或环境变量均无关联。这些基因的低变异性可能是由于多种因素共同作用的结果，例如：（i）蜱最近才传入新热带地区；（ii）种群间存在大规模、有效的快速交换；（iii）气候对目标基因进化速率的影响较小。这些结果对牛蜱侵扰的生态学研究和防治具有重要意义。
