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1 April 2015 Morphometric and demographic differences between tropical and temperate Norway rats (Rattus norvegicus)
Fleur H. Porter, Federico Costa, Gorete Rodrigues, Helena Farias, Marcelo Cunha, Gregory E. Glass, Mitermayer G. Reis, Albert I. Ko, James E. Childs
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Abstract

Rattus norvegicus (Norway rat) is one of the most abundant and geographically widespread mammals. Ecological studies focusing on urban Norway rat populations are restricted to temperate regions, and data describing populations from tropical cities are lacking. We compared the morphometrics and demographic characteristics of rats captured in urban low-income settlements in Salvador, Brazil, to a season, environmental area of capture, and sex-matched sample from Baltimore, Maryland. Norway rats of both sexes were significantly smaller in Salvador, although the threshold mass marking sexual maturity was equivalent for both cities. Pregnancy rates were comparable (∼50%); however, juveniles were commonly trapped in Salvador (20%) while they were rarely trapped in Baltimore during winter months (2%). These findings suggest that tropical and temperate rats differ with respect to body metrics, while size at sexual maturity is similar. Further studies conducted over different seasons are required before any firm conclusions are reached; however, this study provides preliminary support for Bergmann's rule that species at higher absolute latitude are larger than the same species sampled at lower latitudes.

© 2015 American Society of Mammalogists, www.mammalogy.org
Fleur H. Porter, Federico Costa, Gorete Rodrigues, Helena Farias, Marcelo Cunha, Gregory E. Glass, Mitermayer G. Reis, Albert I. Ko, and James E. Childs "Morphometric and demographic differences between tropical and temperate Norway rats (Rattus norvegicus)," Journal of Mammalogy 96(2), 317-323, (1 April 2015). https://doi.org/10.1093/jmammal/gyv033
Received: 24 December 2013; Accepted: 7 April 2014; Published: 1 April 2015
JOURNAL ARTICLE
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KEYWORDS
Bergmann's rule
controle de roedores
ecologia urbana
espécies invasoras
invasive species
Norway rat
rato Norueguês
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