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Negative covariance between parasite load and body condition in a population of feral horses

Published online by Cambridge University Press:  22 March 2016

LUCIE DEBEFFE*
Affiliation:
Department of Biology, University of Saskatchewan, 112 Science Place, Saskatoon, SK S7N 5E2, Canada
PHILIP D. MCLOUGHLIN
Affiliation:
Department of Biology, University of Saskatchewan, 112 Science Place, Saskatoon, SK S7N 5E2, Canada
SARAH A. MEDILL
Affiliation:
Department of Biology, University of Saskatchewan, 112 Science Place, Saskatoon, SK S7N 5E2, Canada
KATHRINE STEWART
Affiliation:
Department of Biology, University of Saskatchewan, 112 Science Place, Saskatoon, SK S7N 5E2, Canada
DANIEL ANDRES
Affiliation:
Department of Biology, University of Saskatchewan, 112 Science Place, Saskatoon, SK S7N 5E2, Canada
TODD SHURY
Affiliation:
Parks Canada Agency, 52 Campus Drive, Saskatoon SK S7N 5B4, Canada
BRENT WAGNER
Affiliation:
Department of Veterinary Microbiology, University of Saskatchewan, 52 Campus drive, Saskatoon, SK S7N 5B4, Canada
EMILY JENKINS
Affiliation:
Department of Veterinary Microbiology, University of Saskatchewan, 52 Campus drive, Saskatoon, SK S7N 5B4, Canada
JOHN S. GILLEARD
Affiliation:
Department of Comparative Biology and Experimental Medicine, University of Calgary, 3330 Hospital Drive, Calgary, AB T2N 4N1, Canada
JOCELYN POISSANT*
Affiliation:
Department of Comparative Biology and Experimental Medicine, University of Calgary, 3330 Hospital Drive, Calgary, AB T2N 4N1, Canada College of Life and Environmental Sciences, University of Exeter, Cornwall Campus, Penryn TR10 9FE, UK
*
*Corresponding authors: Department of Biology, University of Saskatchewan, 112 Science Place, Saskatoon, SK S7N 5E2, Canada. E-mail: lucie.debeffe@gmail.com and Centre for Ecology and Conservation, University of Exeter, Cornwall Campus, Penryn TR10 9FE, UK. E-mail: j.poissant@exeter.ac.uk
*Corresponding authors: Department of Biology, University of Saskatchewan, 112 Science Place, Saskatoon, SK S7N 5E2, Canada. E-mail: lucie.debeffe@gmail.com and Centre for Ecology and Conservation, University of Exeter, Cornwall Campus, Penryn TR10 9FE, UK. E-mail: j.poissant@exeter.ac.uk

Summary

In wild and domestic animals, gastrointestinal parasites can have significant impacts on host development, condition, health, reproduction and longevity. Improving our understanding of the causes and consequences of individual-level variation in parasite load is therefore of prime interest. Here we investigated the relationship between strongyle fecal egg count (FEC) and body condition in a unique, naturalized population of horses that has never been exposed to anthelmintic drugs (Sable Island, Nova Scotia, Canada). We first quantified variation in FEC and condition for 447 individuals according to intrinsic (sex, age, reproductive status, social status) and extrinsic (group size, location, local density) variables. We then quantified the repeatability of measurements obtained over a field season and tested for covariance between FEC and condition. FECs were high relative to other horse populations (mean eggs per gram ± SD = 1543·28 ± 209·94). FECs generally decreased with age, were higher in lactating vs non-lactating females, and unexpectedly lower in males in some part of the island. FECs and condition were both spatially structured, with patterns depending on age, sex and reproductive status. FECs and condition were both repeatable. Most notably, FECs and condition were negatively correlated, especially in adult females.

Type
Research Article
Copyright
Copyright © Cambridge University Press 2016 

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References

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