Abstract
In order to evaluate potential reproductive costs associated with parasitism, we experimentally removed ectoparasites from reproductive female North American red squirrels (Tamiasciurus hudsonicus). Body mass and overwinter survival of mothers, days to juvenile emergence, juvenile survival from birth to emergence, and body mass of juveniles at emergence were all compared to those of untreated (control) animals. Ectoparasite removal did not affect the body mass of mothers throughout the lactation period and overwinter survival of mothers did not differ between treatments and controls. Likewise, there was no effect of treatment on the number of days to juvenile emergence. However, treated mothers raised offspring that were significantly heavier (11%) than controls at emergence. Juveniles from treated mothers were also 24% more likely to survive from birth to emergence. Our results indicate that ectoparasites impose costs on the reproductive success of female red squirrels and that ectoparasites have the potential to influence red squirrel life-histories and population dynamics.
Highlights
Two of the central tenets of life-history theory are that natural selection maximizes fitness and that fitness-related traits are constrained by trade-offs given limited resources [1]
Prevalence of fleas on the litters of treated mothers was 0.0% and 100.0% for control mothers at the time of birth
Prevalence of fleas amongst individual offspring from control mothers at birth was 79.6%, when data from 2010 and 2011 were pooled
Summary
Two of the central tenets of life-history theory are that natural selection maximizes fitness and that fitness-related traits are constrained by trade-offs given limited resources [1]. By imposing considerable energetic costs on their hosts [2,3,4], parasites have been implicated in the development, expression and evolution of many life-history traits [5,6]. Parasites impose considerable energetic and behavioural costs on their hosts [3,8,9,10]. Hosts have to deal with trade-offs between current reproduction, future reproduction, maintenance, survival and the costs associated with parasites. To address these complex trade-offs, parents may adjust the number and quality of their offspring in order to optimize their own reproductive success
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