Seasonal pelage color change: news based on a South American Rodent

Carolina R Camargo,Elton Colares,Ana Maria L Castrucci

doi:10.1590/s0001-37652006000100009

Abstract

Mammalian seasonal molting and color change are known to be influenced by photoperiod changes. Calomys laucha, a South American rodent, exhibits seasonal pelage color change; however, unlike Northern hemisphere rodents, which present a gray or brown color during summer and a whitish color during winter, C. laucha pelage changes from an orange color during summer to a dark gray color during winter. Animals maintained for over a year in stationary photoperiod (LD 12:12h, 22 degrees C) presented orange pelage color during the summer corresponding month (January), and gray color during the winter corresponding month (July). Same age animals were evaluated during summer or winter months, and also showed different colors. Animals exposed for 12 weeks to summer or winter artificial conditions displayed color change, not according to the environmental conditions, as expected, but similar to that of animals maintained in stationary photoperiod. These results suggest that pelage color change in C. laucha is controlled by an endogenous circannual rhythm. The adaptive function of C. laucha color change is discussed.

Highlights

Seasonal alterations in organisms are important to anticipate ambient changes and to begin adjustments to environmental modifications occurring throughout the year
There were no significant differences in the dynamic of color change between males and females (p> 0.05, data not shown), both sexes were grouped for further analyses
Animals from both sexes maintained at stationary photoperiod regimen and controlled temperature for over a year (AR group) presented pelage color change, even away from the natural environment

Summary

Introduction

Seasonal alterations in organisms are important to anticipate ambient changes and to begin adjustments to environmental modifications occurring throughout the year. Molt and weight changes prepare the animal for winter or summer. Minks and squirrels present an endogenous rhythm of molt which is strongly influenced by changes in photoperiod (Martinet et al 1992) or temperature (Joy and Mrosovsky 1985). Both species possess endogenous annual rhythms in body weight (Martinet et al 1992, Pengelley and Asmundson 1969) as do European hamsters (Masson-Pevet et al 1994) and dormice (Mrosovsky 1977)

Objectives

Methods

Results

Conclusion