摘要:

Environmental factors that regulate the sexual activity of male lesser mouse lemurs have been studied experimentally with more than 60 captive animals over an 8-year period. In this nocturnal Malagasy prosimian, variation in day length is the primary factor controlling seasonal sexual activity. Plasma testosterone concentrations were low (= 9 ng/ml) during short days and reached 60 ng/ml during long days (>12-hour day). This cyclic pattern persists unchanged when artificial photoperiodic rhythms are applied and is not altered by ageing. The timing of puberty is also regulated by photoperiodic changes. Nevertheless, the sexual activity of the male lesser mouse lemur can be dramatically modified by the social environment. In heterosexual groups, behavioural and physiological components of sexual activity are depressed in all males except the dominant one, whose aggressive interactions are always successful. Intermale sexual inhibition was shown to be mediated by chemical cues present in the urine of dominant or isolated males but not in urine of subordinate individuals. The inhibitory signals possess lipophilic properties and are not contingent on the gonadal activity of the urine donor but are linked to adrenocortical activity. By contrast, chemical signals stimulating the reproductive function of all males are found in the urine of females, the presence of which is required for the establishment of clear dominance among grouped males. Endocrine mechanisms underlying intermale sexual inhibition by chemical cues were analysed. Variations in prolactin strongly suggest that olfaction interacts with the photoperiodic regulation of reproductive function, leading to changes in the sensitivity of the negative feedback effect of testosterone on gonadotrophin secretion. Inhibitory or stimulatory effects of chemical signals are discussed in the context of their functional significance for wild populations.

ISSN:0015-5713    

DOI:10.1159/000156637

出版商:S. Karger AG    

年代:1992

数据来源: Karger

摘要:

While 3-month-old infant rhesus macaques (Macaca mulatto) were awake and active in social interactions away from their mothers, body and nipple contacts with their mothers were nevertheless made from time to time. In each dyad the proportions of contacts made by the mother nearly equalled those broken by her, suggesting a meshed interaction in which each partner accepted most of the other’s contact initiations and terminations. Passive prevention of nipple contact by a mother reduced the frequency of nipple contact by her infant in the first 5 s after the infant had made body contact. Passive prevention occurred after fewer than 1 in 6 body contacts initiated by infants, and – even without its occurrence – most infants were less ready to take the nipple after their own initiatives than after maternal initiatives. Once nipple contact had been made, the probability of breaking body contact was reduced. The role of maternal rejection both in the control of nipple contact in the short term and in determining (through its effect on the sucking pattern) whether the mother gives birth in the next birth season or later is discussed. We suggest that, by the age of 3 months, the infants had already learned when and how often nipple contact with their mothers would be acceptable during their awake and active periods, and we suggest that subsequent decreases in the frequency of nipple contact were partly the results of maternal rejections which were accepted by the in

ISSN:0015-5713    

DOI:10.1159/000156638

出版商:S. Karger AG    

年代:1992

数据来源: Karger

ISSN:0015-5713    

DOI:10.1159/000156639

出版商:S. Karger AG    

年代:1992

数据来源: Karger

ISSN:0015-5713    

DOI:10.1159/000156640

出版商:S. Karger AG    

年代:1992

数据来源: Karger

ISSN:0015-5713    

DOI:10.1159/000156641

出版商:S. Karger AG    

年代:1992

数据来源: Karger

ISSN:0015-5713    

DOI:10.1159/000156642

出版商:S. Karger AG    

年代:1992

数据来源: Karger

ISSN:0015-5713    

DOI:10.1159/000156643

出版商:S. Karger AG    

年代:1992

数据来源: Karger