title: A simultaneous test of synchrony causal factors in muskrat and mink fur returns at different scales across Canada.
abstract: BACKGROUND
  Synchrony among populations has been attributed to three major hypotheses: dispersal, the Moran effect, and trophic-level interactions. Unfortunately, simultaneous testing of these hypotheses demands complete and detailed data, which are scarce for ecological systems.
  
  
  RESULTS
  Hudson's Bay Company data on mink and muskrat fur returns in Canada represent an excellent opportunity to test these hypotheses because of the detailed spatial and temporal data from this predator-prey system. Using structural equation modelling, support for each hypothesis was evaluated at two spatial scales: across Canada and dividing the country into three regions longitudinally. Our results showed that at both scales mink synchrony is a major factor determining muskrat synchrony, supporting the hypothesis of trophic-level interactions, but the influence of winter precipitation synchrony is also important in eastern Canada. Moreover, mink synchrony is influenced principally by winter precipitation synchrony at the level of all Canada (Moran effect), but by distance at regional level, which might suggest some influence of dispersal at this level.
  
  
  CONCLUSIONS
  Our result is one of the few reports of synchrony mediated by trophic-level interactions, highlighting the importance of evaluation of scale effects in population synchrony studies.
authors.affiliation: Instituto de Ecología y Evolución, Facultad de Ciencias, Universidad Austral de Chile, Valdivia, Chile. sergio.estay@gmail.com
authors.forename: Sergio A
authors.initials: SA
authors.lastname: Estay
authors.forename: Abraham A
authors.initials: AA
authors.lastname: Albornoz
authors.forename: Mauricio
authors.initials: M
authors.lastname: Lima
authors.forename: Mark S
authors.initials: MS
authors.lastname: Boyce
authors.forename: Nils C
authors.initials: NC
authors.lastname: Stenseth
mesh_terms: D000818:Animals; D003411:Arvicolinae; D002170:Canada; D002980:Climate; D008907:Mink; D008954:Models, Biological; D011157:Population Dynamics; D011235:Predatory Behavior
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