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CONDITION DEPENDENCE OF SEXUAL ORNAMENT SIZE AND VARIATION IN THE STALK‐EYED FLY CYRTODIOPSIS DALMANNI (DIPTERA: DIOPSIDAE)
Author(s) -
Cotton Samuel,
Fowler Kevin,
Pomiankowski Andrew
Publication year - 2004
Publication title -
evolution
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.84
H-Index - 199
eISSN - 1558-5646
pISSN - 0014-3820
DOI - 10.1111/j.0014-3820.2004.tb00437.x
Subject(s) - biology , sexual dimorphism , sexual selection , trait , variation (astronomy) , selection (genetic algorithm) , evolutionary biology , analysis of variance , zoology , statistics , physics , artificial intelligence , computer science , astrophysics , programming language , mathematics
We used the stalk‐eyed fly Cyrtodiopsis dalmanni to examine predictions made by condition‐dependent handicap models of sexual selection. Condition was experimentally varied by manipulation of larval food availability. Cyrtodiopsis dalmanni is a highly dimorphic species exhibiting strong sexual selection, and the male sexual ornament (exaggerated eyespan) showed strong condition‐dependent expression relative to the homologous trait in females and nonsexual traits. Male eyespan also showed a great increase in standardized variance under stress, unlike nonsexual traits. The inflated variance of the male ornament was primarily attributable to condition‐dependent (but body‐size‐independent) increase in variance. Thus, evaluation of male eyespan allows females to gain additional information about male condition over and above that given by body size. These findings accord well with condition‐dependent handicap models of sexual selection.