Host–Parasite Association Dynamics Influence Dispersal and Population Genetics of Little Brown Myotis (Myotis lucifugus, Le Conte 1831) Ectoparasites

Host–parasite relationships can affect the dispersal and transmission of parasites. Myodopsylla insignis (Rothchild, 1903), a bat flea, and Spinturnix americanus (Banks, 1902), a bat wing mite, are two common ectoparasites of the little brown myotis (Myotis lucifugus, Le Conte 1831) that differ in life cycles and time spent on the host. Our goal was to compare how life history traits and host–parasite relationships influence the genetic structure and biogeography of co-infecting ectoparasites using S. americanus mites and M. insignis fleas that feed on Myotis lucifugus bats. Ectoparasites were collected from bats captured at maternity roosts between 2010 and 2017 in Atlantic Canada and sequenced for the cytochrome oxidase c subunit 1 gene. We barcoded 223 S. americanus and 87 M. insignis specimens and examined their genetic diversity, genetic structure, and biogeography. We found evidence of a weak association between geographic distance and sequence divergence between Labrador and Nova Scotia for M. insignis and evidence of regional differentiation between the island of Newfoundland and the mainland for S. americanus, similar to previous findings for M. lucifugus. In terms of biogeography, M. insignis likely underwent historical population expansion, particularly in Labrador, whereas S. americanus may have undergone historical population expansion or selection. Our study highlights how host–parasite relationships are influenced at multiple scales by both host and parasite biology and how an understanding of both host and parasite informs predictions on how these dynamics will be affected by disturbances.