منابع مشابه
Yolk androgens reduce offspring survival.
Females may favour some offspring over others by differential deposition of yolk hormones. In American kestrels (Falco sparverius), we found that yolks of eggs laid late in the sequence of a clutch had more testosterone (T) and androstenedione (A4) than yolks of first-laid eggs. To investigate the effects of these yolk androgens on nestling 'fitness', we injected both T and A4 into the yolks of...
متن کاملVariable effects of yolk androgens on growth, survival, and immunity in eastern bluebird nestlings.
Female birds allocate androgens differentially within and among clutches, and it has been suggested that this is a strategy to maximize reproductive success. Only a few studies, however, have examined the effects of yolk testosterone (T) on the growth and development of nestlings, and none have reported on the immunological effects of yolk T nor have they examined several different effects in t...
متن کاملDifferential Effects of Maternal Yolk Androgens on Male and Female Offspring: A Role for Sex-Specific Selection?
Maternal hormones are important mediators of prenatal maternal effects in animals. Although their effects on offspring phenotype are often sex-specific, the reason why sometimes sons are more sensitive to prenatal hormone exposure and sometimes daughters is not well understood. Here I combine an experimental manipulation of yolk testosterone concentration in the egg and quantification of select...
متن کاملYolk androgens vary inversely to maternal androgens in Eastern Bluebirds: an experimental study
1. Female birds deposit variable amounts of androgens in the yolks of their eggs, and it has been suggested that yolk androgen deposition is an adaptive mechanism preparing offspring for a competitive environment. Breeding pairs of Eastern Bluebirds ( Sialia sialis ) Linnaeus were stimulated with an intruder presentation while ovarian follicles were developing. Yolk steroid concentrations in eg...
متن کاملNest composition and yolk hormones: do female European starlings adjust yolk androgens to nest quality?
The nest is a key element of avian reproductive fitness. It provides the developmental environment for the embryo and nestling thereby affecting their quality and survival. Nests are often constructed by the male and nest quality, elaboration, and ornamentation vary among males in a species. Therefore, male nest-building behaviour is likely under sexual selection and females may use male nest-b...
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ژورنال
عنوان ژورنال: Proceedings of the Royal Society of London. Series B: Biological Sciences
سال: 2000
ISSN: 0962-8452,1471-2954
DOI: 10.1098/rspb.2000.1163