Document Detail

Modelling the mating system of polar bears: a mechanistic approach to the Allee effect.
MedLine Citation:
PMID:  18029307     Owner:  NLM     Status:  MEDLINE    
Allee effects may render exploited animal populations extinction prone, but empirical data are often lacking to describe the circumstances leading to an Allee effect. Arbitrary assumptions regarding Allee effects could lead to erroneous management decisions so that predictive modelling approaches are needed that identify the circumstances leading to an Allee effect before such a scenario occurs. We present a predictive approach of Allee effects for polar bears where low population densities, an unpredictable habitat and harvest-depleted male populations result in infrequent mating encounters. We develop a mechanistic model for the polar bear mating system that predicts the proportion of fertilized females at the end of the mating season given population density and operational sex ratio. The model is parametrized using pairing data from Lancaster Sound, Canada, and describes the observed pairing dynamics well. Female mating success is shown to be a nonlinear function of the operational sex ratio, so that a sudden and rapid reproductive collapse could occur if males are severely depleted. The operational sex ratio where an Allee effect is expected is dependent on population density. We focus on the prediction of Allee effects in polar bears but our approach is also applicable to other species.
Péter K Molnár; Andrew E Derocher; Mark A Lewis; Mitchell K Taylor
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Proceedings. Biological sciences / The Royal Society     Volume:  275     ISSN:  0962-8452     ISO Abbreviation:  Proc. Biol. Sci.     Publication Date:  2008 Jan 
Date Detail:
Created Date:  2007-11-27     Completed Date:  2008-04-16     Revised Date:  2013-06-06    
Medline Journal Info:
Nlm Unique ID:  101245157     Medline TA:  Proc Biol Sci     Country:  England    
Other Details:
Languages:  eng     Pagination:  217-26     Citation Subset:  IM    
Centre for Mathematical Biology, Department of Mathematical and Statistical Sciences, University of Alberta, Edmonton, Alberta, Canada.
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MeSH Terms
Arctic Regions
Models, Biological*
Population Density
Sex Ratio
Sexual Behavior, Animal / physiology*
Ursidae / physiology*

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