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Environmental influence and cohort effects in a sexual ornament in the house sparrow, Passer domesticus
Author(s) -
Jensen Henrik,
SvorkmoLundberg Torkild,
Harald Ringsby Thor,
Sæther BerntErik
Publication year - 2006
Publication title -
oikos
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.672
H-Index - 179
eISSN - 1600-0706
pISSN - 0030-1299
DOI - 10.1111/j.2006.0030-1299.14423.x
Subject(s) - passer , sparrow , sexual selection , biology , trait , hatching , population , zoology , sexual maturity , ecology , natural selection , variation (astronomy) , demography , sociology , computer science , programming language , physics , astrophysics
Presence of phenotypic variation is necessary for selection to occur, yet processes affecting variation in sexually selected characters in natural populations are poorly understood. Here we examine whether variation in a sexual ornament (badge size) of male house sparrows ( Passer domesticus ) is dependent on individual variation in the conditions during early ontogenetic stages, and whether this variation and the population‐wide effects of external variables such as weather or population size jointly will generate consistent differences among cohorts later in life. Variation in badge size was independent of adult body size, whereas heavier fledglings and fledglings in good body condition developed smaller visible badges as adults. Furthermore, strong cohort‐effects were present, caused by a combined effect of density‐dependence and weather during the early development in the moulting period and autumn after hatching. Thus, badge size is an environmentally‐dependent trait in house sparrows, and likely to be under the influence of both natural and sexual selection.