CJO - Abstract - The ontogeny and distribution of countershading in colonies of the naked mole-rat (<em>Heterocephalus glaber</em>)

Journal of Zoology (2001), 253: 351-357 Cambridge University Press

Copyright © 2001 The Zoological Society of London

doi:10.1017/S0952836901000322

Published online by Cambridge University Press 12 Feb 2001

The ontogeny and distribution of countershading in colonies of the naked mole-rat (Heterocephalus glaber)

Stanton Braude ^a1^c1, Deborah Ciszek ^a2, Nancy E. Berg ^a3 and Nancy Shefferly ^a4
^a1 International Center for Tropical Ecology at UMSL and Washington University, St Louis, MO 63130, U.S.A.
^a2 University of Michigan, Ann Arbor, MI 48109-1079, U.S.A.
^a3 Washington University, St Louis, MO 63130, U.S.A.
^a4 Oakland Community College, Farmington Hills, MI 48334, U.S.A.

Abstract

Most naked mole-rats Heterocephalus glaber are countershaded, with purple-grey dorsal but pale pink ventral skin. The exceptions to this coloration pattern are uniformly pink, and include newborn pups, most queens and breeding males, and very old animals. Countershading begins to appear at 2–3 weeks of age and begins to disappear at c. 7 years of age. Countershading may provide camouflage when young naked mole-rats are above ground attempting to disperse. Therefore, reproductives and older workers may lose this coloration once they are unlikely to leave the burrow. Alternative hypotheses for pigmentation that we considered include: thermoregulation, and protection from abrasion or from damaging ultraviolet radiation. These hypotheses are not necessarily mutually exclusive, but do lead to different predictions regarding the development of pigmentation and which colony members should be countershaded.

(Accepted February 22 2000)

Key Words: Heterocephalus glaber; naked mole-rat; countershading; adaptive coloration.

Correspondence:
^c1 All correspondence to: Stanton Braude, Biology Department Box 1137, Washington University, St Louis, MO 63130, U.S.A. E-mail: braude@biology.wustl.edu