Browsing by Author "Bender, N."
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- Buffalo Bill and the Danish Ogres: an examination of the concepts of ogres and cavemenPublication . Bender, N.O conceito de Ogre é apresentado na sua relação com a descoberta e reportagemsobre o Neandartal no séc. XIX. Propõe-se que o conceito vulgar do “Homem das Cavernas” é uma generalização recente do Neandartal, Homo sapienssapiensprimitivo e outros fósseis humanóides. os dois conceitos de Ogre e de Homem das Cavernas estão intimamente relacionados na literatura popular do séc. XX, parecendo ter-se entrecruzado e até fundido. Um dos primeiros livros que mostrou a combinação dos dois conceitos foi o romance em folheto de cordel sobreBuffalo Bill, publicado na Dinamarca, história essa que é examinada neste artigo.
- Hormonal control of brood care and social status in a cichlid fish with brood care helpersPublication . Bender, N.; Heg-Bachar, Z.; Oliveira, R. F.; Canario, Adelino V. M.; Taborsky, M.We studied the role of steroid hormones for parental and alloparental brood care and social status in a cooperatively breeding fish. We measured excretion levels of testosterone and 11-ketotestosterone in males, estradiol-17β in females and cortisol in both sexes at different stages of the breeding cycle, and compared these values to data measured in non-reproductive fish. Brood care behaviour does not seem to relate to steroid hormone excretion levels in this species. Steroid hormones varied with social status, however. Non-territorial male aggregation members, for example, showed high testosterone and low 11-ketotestosterone excretion levels, suggesting that they might pursue a “stand-by strategy” for breeding to react quickly if an occasion for breeding arises. Cortisol excretion levels are high in juvenile helpers compared to same-size aggregation members, suggesting higher stress levels in subordinate members of reproductive groups. This is the first study assessing if steroid hormone control mechanisms are involved in brood care and social roles in a cooperatively breeding fish.
- The role of prolactin in the regulation of brood care in the cooperatively breeding fish Neolamprologus pulcherPublication . Bender, N.; Taborsky, M.; Power, DeborahThe hormone prolactin (PRL) is important for the regulation of parental care in many species of mammals, birds and fish, and for alloparental care (care directed at nondescendant young) in some mammals and birds. Its significance in alloparental brood care of cooperatively breeding fish has not yet been assessed. Here, we test the role of PRL in brood care behavior of the cooperatively breeding cichlid Neolamprologus pulcher. The expression of PRL mRNA was determined in the pituitary glands of breeders of both sexes, helpers that showed brood care behavior and nonbreeding fish as controls. In addition, PRL levels were experimentally manipulated in male breeders and helpers by intraperitoneal injections of ovine PRL, and the behavior of these test fish was recorded toward standardized clutches. Adult females had higher levels of PRL mRNA than adult males, which was true both for breeders and nonbreeders. Contrary to expectation, there was no positive correlation between PRL and brood care behavior in any category of test fish, and the experimental application of PRL did not change brood care propensity. Interestingly, brood-caring adult females had significantly lower levels of PRL mRNA than adult female nonbreeders, whereas there was no difference between helpers and similar-sized nonbreeding group members. PRL mRNA levels increased with body mass in juveniles, but decreased with body mass in adults. In conclusion, we found no evidence that elevated levels of PRL are directly involved in the regulation of brood care behavior in this species.