Vertical vs. horizontal transmission of the microbiome in a key disease vector,Ixodes pacificus |
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| Authors: | Jessica Y. Kwan Reid Griggs Betsabel Chicana Caitlin Miller Andrea Swei |
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| Affiliation: | 1. Department of Biology, San Francisco State University, San Francisco, CA, USA;2. Department of Viticulture and Enology, University of California, Davis, CA, USA;3. Department of Quantitative and Systems Biology, University of California, Merced, CA, USA |
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| Abstract: | Vector‐borne pathogens are increasingly found to interact with the vector's microbiome, influencing disease transmission dynamics. However, the processes that regulate the formation and development of the microbiome are largely unexplored for most tick species, an emerging group of disease vectors. It is not known how much of the tick microbiome is acquired through vertical transmission vs. horizontally from the environment or interactions with bloodmeal sources. Using 16S rRNA sequencing, we examined the microbiome of Ixodes pacificus, the vector of Lyme disease in the western USA, across life stages and infection status. We also characterized microbiome diversity in field and laboratory‐collected nymphal ticks to determine how the surrounding environment affects microbiome diversity. We found a decrease in both species richness and evenness as the tick matures from larva to adult. When the dominant Rickettsial endosymbiont was computationally removed from the tick microbial community, we found that infected nymphs had lower species evenness than uninfected ticks, suggesting that lower microbiome diversity is associated with pathogen transmission in wild‐type ticks. Furthermore, laboratory‐reared nymph microbiome diversity was found to be compositionally distinct and significantly depauperate relative to field‐collected nymphs. These results highlight unique patterns in the microbial community of I. pacificus that is distinct from other tick species. We provide strong evidence that ticks acquire a significant portion of their microbiome through exposure to their environment despite a loss of overall diversity through life stages. We provide evidence that loss of microbial diversity is at least in part due to elimination of microbial diversity with bloodmeal feeding but other factors may also play a role. |
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| Keywords: | 16S rRNA
Borrelia burgdorferi
endosymbiont
Ixodes pacificus
life stages microbiome |
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