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Title: Temporal and spatial mosaics: deep host association and shallow geographic drivers shape genetic structure in a widespread pinworm, Rauschtineria eutamii

Author
item BELL, KAYCE - University Of New Mexico
item KENDALL, CALHOUN - University Of California
item Hoberg, Eric
item DEMBOSKI, JOHN - Denver Museum Of Nature And Science
item COOK, JOSEPH - University Of New Mexico

Submitted to: Biological Journal of the Linnean Society, London
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/18/2015
Publication Date: 5/26/2016
Citation: Bell, K.C., Kendall, C., Hoberg, E.P., Demboski, J.R., Cook, J.A. 2016. Temporal and spatial mosaics: deep host association and shallow geographic drivers shape genetic structure in a widespread pinworm, Rauschtineria eutamii. Biological Journal of the Linnean Society, London. 119:397-413.

Interpretive Summary: An understanding of genetic diversity and geographic distribution among hosts and parasites is an initial step in identifying abiotic and biotic drivers that have shaped the occurrence and evolution of complex biological assemblages and which contribute to patterns of disease space and time. Climate and population structure among hosts are 2 important factors that shape pathogen diversity and which are independent of coevolutionary histories (associations of lineages by descent through time). We applied molecular-based data to reveal the history and genetics of a pinworm-species (Rauschtineria) that infects 10 species of chipmunks (rodents) in western North America. A powerful model for understanding the role of climate, geography and host evolution emerges from a study of these chipmunk nematodes (roundworms). We demonstrate that cospeciation in this assemblage was minimal although the association of hosts and parasites was of substantial duration in evolutionary time. Secondarily, patterns of shallow divergence were shaped by geography through events or episodic bouts of geographic and host colonization coincidental with cycles of climate change. Significantly this study validates a suite of new concepts about the nature of host-parasite associations which emphasize the importance of host switching and complexity in evolution of pathogens and faunal assembly. These are basic insights of importance to disease ecologists, veterinarians and the medical community in highlighting the mechanisms that are related to the distribution of pathogens and emergence of disease.

Technical Abstract: Climate and host demographic cycling often shape both parasite genetic diversity and host distributions, processes that transcend a history of strict host-parasite association. We explored these processes based on an evaluation of mitochondrial cytochrome oxidase c subunit I (COI) sequences to reveal history and genetic structure of a pinworm, Rauschtineria eutamii, infecting 10 species of western North American chipmunks (Rodentia:Tamias). Rauschtineria eutamii contains divergent lineages influenced by the diversity of hosts and variation across the complex topography of western North America. We recovered five reciprocally monophyletic R. eutamii clades exhibiting divergence levels comparable to intraspecific variation reported for other nematodes. Phylogenetic relationships among pinworm clades suggest that ancestral R. eutamii colonized a precursor of Neotamias and persisted during historical isolation in a host species or species group; pinworm diversification, however, is incongruent and asynchronous relative to host diversification. Secondarily, patterns of shallow divergence were shaped by geography through events of episodic colonization reflecting an interaction of taxon pulses and ecological fitting among assemblages in recurrent sympatry. Pinworms occasionally infect geographically proximal host species; however host-switching may be unstable or ephemeral, as there is no signal of host-switching in the deeper history of R. eutamii.