Date Approved

1-9-2025

Graduate Degree Type

Thesis

Degree Name

Biology (M.S.)

Degree Program

Biology

First Advisor

Paul Keenlance

Second Advisor

Joe Jacquot

Third Advisor

Maria Spriggs

Fourth Advisor

Michael Joyce

Academic Year

2024/2025

Abstract

Southern flying squirrels (Glaucomys volans) are rapidly expanding their range north due to warming temperatures. Northern flying squirrel (Glaucomys sabrinus) distribution has retracted northwards in response to southern flying squirrels’ ability to outcompete northern flying squirrels. This competition plays out through many mechanisms, including parasite mediated competition. Both flying squirrel species can be infected by the intestinal parasite Strongyloides robustus. Previous research has suggested that interactions between the northern and southern flying squirrels are influenced at least in part through S. robustus and parasite mediated competition, yet questions remain on transmission pathways. In this study, we sought to 1) compare the prevalence of S. robustus between northern flying squirrel populations with and without southern flying squirrels present; 2) identify and record any intestinal parasite present in all squirrel species sampled; and 3) test for negative health effects on infected hosts for each parasite found using body condition as a proxy for general health. Northern and southern flying squirrels, along with red squirrels (Tamiasciurus hudsonicus), gray squirrels (Sciurus carolinensis), and chipmunks (Tamias striatus) were trapped throughout Minnesota based on the sympatry or allopatry of flying squirrels. Squirrels were tested for S. robustus and any other identifiable parasite eggs via a modified McMaster fecal float technique and body condition was derived through the scaled mass index. We report S. robustus from an allopatric northern flying squirrel where no southern flying squirrels were present, but overall prevalence of S. robustus was very low throughout our study area. We identified five additional parasites to the finest taxonomic scale possible, Eimeria spp., Eimeria ontarioensis, Capillaria spp., Trichuris spp., and an unidentified parasite. The prevalence of parasite species was variable for different squirrel species and parasites had no significant effect on body condition for any parasite host 5 combination, although some approached significance and warrant further study. We conclude that S. robustus and parasite-mediated competition do not play a significant role in this system at this time. This study provides important baseline data on parasite prevalence in Minnesota tree squirrels in the context of a rapidly changing environment due to climate change.

Comments

In collaboration with the Natural Resources Research Institute of University of Minnesota Duluth.

Available for download on Thursday, January 14, 2027

Included in

Biology Commons

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