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Sexual dimorphism in a marsupial: seasonal and lifetime differences in sex-specific mass

Sexual dimorphism in a marsupial: seasonal and lifetime differences in sex-specific mass Whereas sexual dimorphism in body mass is common in many vertebrates, the developmental mechanisms leading to diverging growth patterns between the sexes are poorly understood in mammals. In the present study, I investigate seasonal and lifetime differences in sex-specific mass in a marsupial, the common brushtail possum ( Trichosurus vulpecula ). From the age of 2 years, males were heavier than females, but significant dimorphism was evident only at the age of 4 years. Annual mass gain was greater in males than in females from 2 to 4 years of age. The body mass of both sexes fluctuated throughout the year, although patterns differed: females lost mass during lactation in winter, whereas males lost mass during the breeding season in later summer and autumn. The mass of a juvenile predicted its mass as an adult for males, but not females. Male-biased sexual dimorphism in mass of possums appears to arise through a combination of a greater rate and duration of mass gain in young males, and the diversion of somatic reserves away from growth and into reproduction in females. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Australian Journal of Zoology CSIRO Publishing

Sexual dimorphism in a marsupial: seasonal and lifetime differences in sex-specific mass

Australian Journal of Zoology , Volume 54 (1) – Mar 23, 2006

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Publisher
CSIRO Publishing
Copyright
CSIRO
ISSN
0004-959X
eISSN
1446-5698
DOI
10.1071/ZO05060
Publisher site
See Article on Publisher Site

Abstract

Whereas sexual dimorphism in body mass is common in many vertebrates, the developmental mechanisms leading to diverging growth patterns between the sexes are poorly understood in mammals. In the present study, I investigate seasonal and lifetime differences in sex-specific mass in a marsupial, the common brushtail possum ( Trichosurus vulpecula ). From the age of 2 years, males were heavier than females, but significant dimorphism was evident only at the age of 4 years. Annual mass gain was greater in males than in females from 2 to 4 years of age. The body mass of both sexes fluctuated throughout the year, although patterns differed: females lost mass during lactation in winter, whereas males lost mass during the breeding season in later summer and autumn. The mass of a juvenile predicted its mass as an adult for males, but not females. Male-biased sexual dimorphism in mass of possums appears to arise through a combination of a greater rate and duration of mass gain in young males, and the diversion of somatic reserves away from growth and into reproduction in females.

Journal

Australian Journal of ZoologyCSIRO Publishing

Published: Mar 23, 2006

References