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CLIMATIC AND TEMPORAL EFFECTS ON THE EXPRESSION OF SECONDARY SEXUAL CHARACTERS: GENETIC AND ENVIRONMENTAL COMPONENTS
Author(s) -
Garant Dany,
Sheldon Ben C.,
Gustafsson Lars
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.tb01685.x
Subject(s) - biology , heritability , genetic variation , sexual selection , genetic correlation , genetic variability , population , zoology , ecology , evolutionary biology , demography , genetics , genotype , sociology , gene
Despite great interest in sexual selection, relatively little is known in detail about the genetic and environmental determinants of secondary sexual characters in natural populations. Such information is important for determining the way in which populations may respond to sexual selection. We report analyses of genetic and large‐scale environmental components of phenotypic variation of two secondary sexual plumage characters (forehead and wing patch size) in the collared flycatcher Ficedula albicollis over a 22‐year period. We found significant heritability for both characters but little genetic covariance between the two. We found a positive association between forehead patch size and a large‐scale climatic index, the North Atlantic Oscillation (NAO) index, but not for wing patch. This pattern was observed in both cross‐sectional and longitudinal data suggesting that the population response to NAO index can be explained as the result of phenotypic plasticity. Heritability of forehead patch size for old males, calculated under favorable conditions (NAO index median), was greater than that under unfavorable conditions (NAO index < median). These changes occurred because there were opposing changes in additive genetic variance (V A ) and residual variance (V R ) under favorable and unfavorable conditions, with V A increasing and V R decreasing in good environments. However, no such effect was detected for young birds, or for wing patch size in either age class. In addition to these environmental effects on both phenotypic and genetic variances, we found evidence for a significant decrease of forehead patch size over time in older birds. This change appears to be caused by a change in the sign of viability selection on forehead patch size, which is associated with a decline in the breeding value of multiple breeders. Our data thus reveal complex patterns of environmental influence on the expression of secondary sexual characters, which may have important implications for understanding selection and evolution of these characters.