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Science. 2012 Aug 17;337(6096):860-4. doi: 10.1126/science.1224286. Epub 2012 Jul 26.

A mechanism of extreme growth and reliable signaling in sexually selected ornaments and weapons.

Author information

1
Division of Biological Sciences, The University of Montana, 104 Health Science Building, Missoula, MT 59812, USA. doug.emlen@mso.umt.edu

Abstract

Many male animals wield ornaments or weapons of exaggerated proportions. We propose that increased cellular sensitivity to signaling through the insulin/insulin-like growth factor (IGF) pathway may be responsible for the extreme growth of these structures. We document how rhinoceros beetle horns, a sexually selected weapon, are more sensitive to nutrition and more responsive to perturbation of the insulin/IGF pathway than other body structures. We then illustrate how enhanced sensitivity to insulin/IGF signaling in a growing ornament or weapon would cause heightened condition sensitivity and increased variability in expression among individuals--critical properties of reliable signals of male quality. The possibility that reliable signaling arises as a by-product of the growth mechanism may explain why trait exaggeration has evolved so many different times in the context of sexual selection.

PMID:
22837386
DOI:
10.1126/science.1224286
[Indexed for MEDLINE]
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