Evolutionary changes in symbiont community structure in ticks |
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| Authors: | Olivier Duron Florian Binetruy Valérie Noël Julie Cremaschi Karen D McCoy Céline Arnathau Olivier Plantard John Goolsby Adalberto A Pérez de León Dieter J A Heylen A Raoul Van Oosten Yuval Gottlieb Gad Baneth Alberto A Guglielmone Agustin Estrada‐Peña Maxwell N Opara Lionel Zenner Fabrice Vavre Christine Chevillon |
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| Affiliation: | 1. Laboratoire MIVEGEC (Maladies Infectieuses et Vecteurs: Ecologie, Génétique, Evolution et Contr?le), Centre National de la Recherche Scientifique (UMR5290) – Institut pour la Recherche et le Développement (UR224) – Université de Montpellier, Montpellier, France;2. BIOEPAR, INRA, Oniris, Nantes, France;3. Cattle Fever Tick Research Laboratory, USDA‐ARS, Edinburg, TX, USA;4. Knipling‐Bushland U.S. Livestock Insects Research Laboratory, Veterinary Pest Genomics Center, Kerrville, TX, USA;5. Evolutionary Ecology Group, University of Antwerp, Antwerp, Belgium;6. Koret School of Veterinary Medicine, The Hebrew University of Jerusalem, Rehovot, Israel;7. Instituto Nacional de Tecnología Agropecuaria, Estación Experimental Agropecuaria Rafaela and Consejo Nacional de Investigaciones Científicas y Técnicas, Santa Fe, Argentina;8. Department of Animal Pathology, Faculty of Veterinary Medicine, University of Zaragoza, Zaragoza, Spain;9. Ticks and Tick‐borne Pathogens Research Unit (TTbPRU), Department of Veterinary Parasitology and Entomology, University of Abuja, Abuja, Nigeria;10. Laboratoire de Biométrie et Biologie évolutive (LBBE), Centre National de la Recherche Scientifique (UMR5558) – Université Claude Bernard Lyon 1, Villeurbanne, France |
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| Abstract: | Ecological specialization to restricted diet niches is driven by obligate, and often maternally inherited, symbionts in many arthropod lineages. These heritable symbionts typically form evolutionarily stable associations with arthropods that can last for millions of years. Ticks were recently found to harbour such an obligate symbiont, Coxiella‐LE, that synthesizes B vitamins and cofactors not obtained in sufficient quantities from blood diet. In this study, the examination of 81 tick species shows that some Coxiella‐LE symbioses are evolutionarily stable with an ancient acquisition followed by codiversification as observed in ticks belonging to the Rhipicephalus genus. However, many other Coxiella‐LE symbioses are characterized by low evolutionary stability with frequent host shifts and extinction events. Further examination revealed the presence of nine other genera of maternally inherited bacteria in ticks. Although these nine symbionts were primarily thought to be facultative, their distribution among tick species rather suggests that at least four may have independently replaced Coxiella‐LE and likely represent alternative obligate symbionts. Phylogenetic evidence otherwise indicates that cocladogenesis is globally rare in these symbioses as most originate via horizontal transfer of an existing symbiont between unrelated tick species. As a result, the structure of these symbiont communities is not fixed and stable across the tick phylogeny. Most importantly, the symbiont communities commonly reach high levels of diversity with up to six unrelated maternally inherited bacteria coexisting within host species. We further conjecture that interactions among coexisting symbionts are pivotal drivers of community structure both among and within tick species. |
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| Keywords: | co‐evolution heritable symbiont communities maternally inherited bacteria symbiosis tick |
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