DOI: 10.5061/dryad.s4dv0
title: Data from: Loss of migratory behavior increases infection risk for a butterfly host

description: Long-distance animal migrations have important consequences for infectious
 disease dynamics. In some cases, migration lowers pathogen transmission by
 removing infected individuals during strenuous journeys and allowing
 animals to periodically escape contaminated habitats. Human activities are
 now causing some migratory animals to travel shorter distances or form
 sedentary (non-migratory) populations. We focused on North American
 monarch butterflies and a specialist protozoan parasite to investigate how
 the loss of migratory behaviours affects pathogen spread and evolution.
 Each autumn, monarchs migrate from breeding grounds in the eastern US and
 Canada to wintering sites in central Mexico. However, some monarchs have
 become non-migratory and breed year-round on exotic milkweed in the
 southern US. We used field sampling, citizen science data and experimental
 inoculations to quantify infection prevalence and parasite virulence among
 migratory and sedentary populations. Infection prevalence was markedly
 higher among sedentary monarchs compared with migratory monarchs,
 indicating that diminished migration increases infection risk. Virulence
 differed among parasite strains but was similar between migratory and
 sedentary populations, potentially owing to high gene flow or insufficient
 time for evolutionary divergence. More broadly, our findings suggest that
 human activities that alter animal migrations can influence pathogen
 dynamics, with implications for wildlife conservation and future disease
 risks.
description: Protozoan infection
 prevalence data from migratory and non-migratory
 monarchsThese data show the
 number of infected (and total) monarchs found per site when citizen
 scientists or the authors tested monarch butterflies for the protozoan
 parasite Ophryocystis elektroscirrha (OE). We were interested in
 differences in infection prevalence for migratory vs. sedentary
 (non-migratory) monarchs. Sites were located in one of several source
 populations: the monarchs' summer-breeding range (migratory
 monarchs), Mexico overwintering areas (migratory monarchs),
 winter-breeding areas (non-migratory monarchs), or at coastal
 overwintering areas. One line of data shows results from one site for one
 year of the study (year 1 = 2011-2012 and year 2= 2012-2013). For each
 site and year, geographic coordinates, observer initials, city, state,
 number of total samples, and number of infected samples are listed. We
 calculated prevalence for sites with 8 or more total samples per year.
 Prevalence is the proportion of total samples that were heavily infected
 with OE. Prevalence was arc-sine-square-root-transformed. Each site was
 also assigned to a sub-region, as detailed in the Electronic Supplementary
 Material.Prevalence data, Satterfield,
 Maerz and Altizer 2014 site
 abbrev.xlsxVirulence for parasite
 isolates collected from migratory vs. non-migratory
 monarchsThese data show results
 of an experiment to compare the virulence of Ophryocystis elektroscirrha
 (OE) parasites from migratory vs. non-migratory monarch butterflies. In
 the laboratory, monarch larvae (2nd instars) were inoculated with 10
 parasite spores from one of 57 parasite isolates (indicated by parasite
 ID) and then reared to adulthood. The source population of each
 wild-collected parasite isolate is listed. Details on parasite origins are
 available in the Electronic Supplementary Material. Experimental monarchs
 originated from one of five monarch lineages (or families), which were
 randomly assigned to treatments. We inoculated 10 larvae for each isolate
 and also reared 80 additional control larvae which were not inoculated.
 Larvae were given fresh, uncontaminated milkweed following inoculation.
 Key dates, including date of inoculation, monarch pupation, monarch
 eclosion and monarch death are listed. When monarchs were in the pupa
 stage, we weighed each pupa (pupal weight in grams) and also noted signs
 of OE disease (dark patches on the pupa), ranking the pupal infection on a
 scale from 0 to 5. A pupal score of 0 indicates no dark patches due to OE
 on the pupa, a score of 1 indicates minimal patching, 2 indicates about
 25% of the pupa shows dark patches, 3 indicates about 50%, 4 indicates
 about 75%, and 5 indicates about 100% of the pupa showing darkening due to
 OE spores under the cuticle. We pupal-scored each monarch starting on day
 6 of pupation and repeated this daily until eclosion. Monarchs with a
 maximum pupal score of 0 or 1 were tested for the parasite after eclosion
 using the tape method described in the manuscript -- in order to verify
 absence of infection. All monarchs were classified as either uninfected or
 infected (infected = having a pupal score of 2 or higher, or an adult
 infection tape-score of 4 or higher). All adult monarchs were kept at 12C
 and day of death was noted. Adult longevity (days until death) was
 calculated and used as a proxy of parasite virulence (shorter adult
 longevity indicates higher parasite virulence). After death, we quantified
 the parasite load on each infected monarch's abdomen, as described in
 the manuscript. Parasite load was log-transformed. Monarch sex is also
 indicated.Virulence data, Satterfield,
 Maerz, and Altizer 2014.xlsx