The Amblyomma maculatum Koch, 1844 (Acari: Ixodidae) group of ticks: phenotypic plasticity or incipient speciation?

• Autores: Lado, Paula; Nava, Santiago; Mendoza-Uribe, Leonardo; Caceres, Abraham G.; Delgado de la Mora, Jesus; Licona Enriquez, Jesus D.; Delgado de la Mora, David; Labruna, Marcelo B.; Durden, Lance A.; Allerdice, Michelle E.J.; Paddock, Christopher D.; Szabó, Matias P.J.; Venzal, José Manuel; Guglielmone, Alberto; Beati, Lorenza
• Año de publicación: 2018
• Idioma: inglés
• Tipo de recurso: artículo
• Fuente: Parasites & Vectors 11 : 610 (December 2018)
• Materia: Amblyomma; Amblyomma maculatum; Acarina; Taxonomía; Fenotipos; Morfología; Taxonomy; Phenotypes; Morphology; Garrapatas
• Institución: Instituto Nacional de Tecnología Agropecuaria

Background; The goal of this study was to reassess the taxonomic status of A. maculatum, A. triste and A. tigrinum by phylogenetic analysis of five molecular markers [four mitochondrial: 12S rDNA, 16S rDNA, the control region (DL) and cytochrome c oxidase 1 (cox1), and one nuclear: ribosomal intergenic transcribed spacer 2 (ITS2)]. In addition, the phenotypic diversity of adult ticks identified as A. maculatum and A. triste from geographically distinct populations was thoroughly re-examined. Results: Microscopic examination identified four putative morphotypes distinguishable by disjunct geographical ranges, but very scant fixed characters. Analysis of the separated mitochondrial datasets mostly resulted in conflicting tree topologies. Nuclear gene sequences were almost identical throughout the geographical ranges of the two species, suggesting a very recent, almost explosive radiation of the terminal operational taxonomic units. Analysis of concatenated molecular datasets was more informative and indicated that, although genetically very close to the A. maculatum - A. triste lineage, A. tigrinum was a monophyletic separate entity. Within the A. maculatum - A. triste cluster, three main clades were supported. The two morphotypes, corresponding to the western North American and eastern North American populations, consistently grouped in a single monophyletic clade with many shared mitochondrial sequences among ticks of the two areas. Ticks from the two remaining morphotypes, south-eastern South America and Peruvian, corresponded to two distinct clades. Conclusions: Given the paucity of morphological characters, the minimal genetic distance separating morphotypes, and more importantly the fact that two morphotypes are genetically indistinguishable, our data suggest that A. maculatum and A. triste should be synonymized and that morphological differences merely reflect very recent local adaptation to distinct environments in taxa that might be undergoing the first steps of speciation but have yet to complete lineage sorting. Nonetheless, future investigations using more sensitive nuclear markers and/or crossbreeding experiments might reveal the occurrence of very rapid speciation events in this group of taxa. Tentative node dating revealed that the A. tigrinum and A. maculatum - A. triste clades split about 2 Mya, while the A. maculatum - A.triste cluster radiated no earlier than 700,000 years ago.
EEA Rafaela
Fil: Lado, Paula. Georgia Southern University. Institute for Coastal Plain Science. United States National Tick Collection; Estados Unidos
Fil: Nava, Santiago. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Rafaela; Argentina
Fil: Mendoza-Uribe, Leonardo. Instituto Nacional de Salud. Laboratorio de Entomología; Perú
Fil: Cáceres, Abraham G. Universidad Nacional Mayor de San Marcos. Facultad de Medicina. Departamento Académico de Microbiología Médica; Perú. Instituto Nacional de Salud. Laboratorio de Entomología; Peru
Fil: Delgado de la Mora, Jesus. University of Sonora. Department of Medicine and Health Sciences; México
Fil: Licona Enriquez, Jesus D. University of Sonora. Department of Medicine and Health Sciences; México
Fil: Delgado de la Mora, David. Technologic Institute of Sonora. Department of Agronomic and Veterinary Sciences; México
Fil: Labruna, Marcelo B. Universidade de São Paulo. Faculdade de Medicina Veterinária e Zootecnia. Departamento de Medicina Veterinária Preventiva e Saúde Animal; Brasil
Fil: Durden, Lance A. Georgia Southern University. Department of Biology; Estados Unidos
Fil: Allerdice, Michelle E. J. Centers for Disease Control and Prevention. National Center for Emerging and Zoonotic Infectious Diseases. Rickettsial Zoonoses Branch; Estados Unidos
Fil: Paddock, Christopher D. Centers for Disease Control and Prevention. National Center for Emerging and Zoonotic Infectious Diseases. Rickettsial Zoonoses Branch; Estados Unidos
Fil: Szabó, Matías P.J. Universidade Federal de Uberlandia. Faculdade de Medicina Veterinaria e Zootecnia. Laboratório de Ixodologia; Brasil
Fil: Venzal, José Manuel. Universidad de la República. CENUR Litoral Norte-Salto. Facultad de Veterinaria. Departamento de Parasitología Veterinaria; Uruguay
Fil: Guglielmone, Alberto. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Rafaela; Argentina
Fil: Beati, Lorenza. Georgia Southern University. Institute for Coastal Plain Science. United States National Tick Collection; Estados Unidos