This site uses cookies. By continuing to browse the site you are agreeing to our use of cookies. I accept this policy Find out more here > Maternal yolk androgens in European starlings: af... Maternal yolk androgens in European starlings: affected by social environment or individual traits of the mother? + Tax (if applicable) Volume 145, Issue 1, BREEDING DENSITY AND SOCIAL COMPETITION; Subscription and article submission information Social competition among female birds has been shown to positively affect yolk androgen levels, perhaps providing a mechanism to communicate environmental conditions to offspring. Whether this relationship is due to social density or to differences among mothers that breed in different social situations is unclear. We manipulated breeding density to test these alternative explanations. Yolk androgens were measured in clutches of European starlings, Sturnus vulgaris, breeding in consecutive years in outdoor aviaries of different sizes and with varying numbers of breeding pairs.
Testosterone (T) levels increased significantly with increasing density. Dihydrotestosterone (DHT) levels increased with the number of nest boxes available. The number of nest boxes monopolized by a breeding male negatively affected androstenedione (A4) levels, positively affected DHT levels and did not affect T levels. Other factors related to social interactions or competition among females (including polygyny) did not influence yolk hormone levels. Within-female yolk androgen levels were highly consistent over two consecutive years even though females were breeding in opposite breeding densities during each year, suggesting that individual characteristics are important determinants of variation in maternal androgen allocation in addition to potential effects of environmental conditions. This within-female consistency of yolk androgen levels across years has important implications. 1: Department of Biology, University of Antwerp, Universiteitsplein 1, B-2610, Wilrijk, Belgium; Behavioural Biology, University of Groningen, P.O. Box 14, 9750 AA, Haren, The Netherlands;
Percy FitzPatrick Institute of African Ornithology, University of Cape Town, Rondebosch 7701, Cape Town, South Africa; 2: Department of Biology, University of Antwerp, Universiteitsplein 1, B-2610, Wilrijk, Belgium; 3: Behavioural Biology, University of Groningen, P.O. Box 14, 9750 AA, Haren, The Netherlands Data & Media loading... Most cited this month Observational Study of Behavior: Sampling Methods The Social Organisation of Antelope in Relation To Their Ecology An Ecological Model of Female-Bonded Primate Groups A Comparison of the Social Postures of Some Common Laboratory Rodents Why Are Diurnal Primates Living in Groups? > Hormonal Induction of the Aquatic Phonotactic Res... Hormonal Induction of the Aquatic Phonotactic Response of Xenopus by Volume 84, Issue 1, Une réponse phonotactique a été induite avec des X. laevis femelles en utilisant du gonadotopin chorionique de provenance humaine. Il s'ensuivait un mouvement délibéré et caractéristique vers un haut-parleur placé dans l'eau qui diffusait des appels nuptiaux conspécifiques.
Les mâles, en appelant détectent d'autres grenouilles près d'eux par des effets de compression dans l'eau. On a remarqué une variabilité dans l'intensité de la réponse aux appels nuptiaux chez les femelles traitées avec l'hormone. Environ 52% des femelles produisant une réponse phonotactique positive ont aussi montré un comportement mâle. Lorsqu'elles furent présentées avec des appels nuptiaux de X. laevis mélangées avec ceux de X. muelleri, les X. laevis femelles ne réagissaient qu'aux appels conspécifiques. Ces appels diffèrent dans leurs taux de pulsation et dans leur structure. L'habilité des femelles de X. laevis à réagir uniquement aux appels conspécifiques explique la rareté d'hybrides naturels dans les régions de sympatrie avec X. muelleri aussi que la facilité avec laquelle les hybrides sont obtenus au laboratoire, ou la fonction de l'appel nuptial est effectivement éliminé. 1: (Zoology Department, University of Cape Town, Rondebosch 7700, Cape Town, R.S.A.
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