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

## TL;DR

This study compares how two bat ectoparasites differ in genetic structure and dispersal patterns due to their life histories and host relationships in Atlantic Canada.

## Contribution

The study reveals how host–parasite dynamics influence parasite dispersal and population genetics at multiple scales.

## Key findings

- M. insignis shows weak geographic distance-genetic divergence in Labrador and Nova Scotia.
- S. americanus exhibits regional differentiation between Newfoundland and the mainland.
- M. insignis likely experienced historical population expansion, while S. americanus may have undergone expansion or selection.

## Abstract

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.

Spinturnix americanus and
Myodopsylla insignis
are two common ectoparasites of little brown myotis (
Myotis lucifugus
) with different life history strategies. These ectoparasites exhibit corresponding differences in genetic diversity and dispersal with their hosts across Atlantic Canada.