No description available.

No description available.

The copulatory performance of male rats (Sprague-Dawley) was quantified, and the factor analytic technique applied to the data. Since factor analysis assesses common variance, subject selection was organized so as to maximize behavioral heterogeniety. Three factors were retained in the statistical analysis. The variables in two factors, Copulatory Efficiency and Initiation, were similar to those contained in the two factors posited by Beach (1956). The third factor was Intromission Count; it contained 2 variables, intromission frequency (IF) and post-ejaculatory interval (PEI). Unlike the variables in the other two factors, however, IF and PEI were not significantly correlated in a simple correlation analysis. The absence of a correlation suggested that the Intromission Count factor contained a suppressor variable. Although the identity of the hypothesized suppressor variable is not known, others have shown that IF and PEI are systematically related to adrenal hormones, the female's behavior and to dominance position. Therefore, the present results suggest that the Intromission Count factor may bear a significant relationship to a broad range of social behaviors, in addition to copulation. In a second experiment an attempt was made to independently manipulate the Initiation and Copulatory Efficiency factors by making elecrolytic lesions of either the median or dorsal raphe nuclei. While there were no significant differences among the groups on measures of copulatory or non-copulatory social behav- iors, a pattern of differences in those behaviors emerged which suggested that the serotonergic system may interact with the olfactory system to influence the two copulation factors. / Master of Science

Call number: LD2668 .T4 1984 L385 / Master of Science

Call number: LD2668 .T4 1984 N37 / Master of Science

I correlated the plasma titers of testosterone (T), estradiol (E), luteinizing hormone (LH), progesterone (P), corticosterone (B) and prolactin (Prl) with the reproductive behavior of breeders and adult and juvenal-plumaged helpers of the Harris' Hawk. During nest building, breeding males and adult male helpers had higher T levels than those in immature male helpers. Among females, only breeders had elevated T levels during nest building. During nest building, breeding females had higher E levels than those in adult and immature females helpers. Patterns of LH were similar to those of T and E. Concentrations of P and B varied only with handling time. During incubation, Prl titers were elevated only in breeding males and females. In contrast to other altricial species, all breeders showed no elevation in Prl levels during feeding of young. Among males, adult male helpers had the highest Prl levels while feeding young.

Call number: LD2668 .T4 1986 H644 / Master of Science / Anatomy and Physiology

Thesis submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg in fulfilment of the requirements for the degree of Master of Science. / Breeding was observed in the foam nest frog, Chiromantis xerampelina, over three breeding seasons The mating pattern was characterized by an extended breeding season with a male-biased operational sex ratio and asynchronous and unpredictable female arrival. At more than 90% of nests, from one to seven unpaired males ('peripheral males') gathered around the amplexing pair during nest construction. Those peripheral males closest to the pair competed 'With each other, and with the amplexing male, to position their cloacae against the female's cloaca during oviposition bouts. In a detailed study of a single population, over 80% of males were observed as peripheral males, and 57% of males were observed both in amplexus and as peripheral males. Male mating success and participation at nests was unrelated to size or weight. Chorus participation was the best predictor of male, mating success and participation at nests. The most plausible explanation for the presence of peripheral males was a sperm competition hypothesis; namely that peripheral males compete with the amplexing male for fertilizations by shedding sperm into the nest. I collected data on body mass and testis mass for 13 African anurans. Using additional published data on 19 Japanese anurans, an allometric relationship between body mass and testis mass was calculated. using 16 genera as independent data points. This revealed that C. xerampelina have testes fourteen times heavier than predicted on the basis of body mass. This is consistent with a trend seen in several taxa where testis size is related to the intensity of sperm competition. An additional experiment, in which the arnplexing male was prevented from shedding sperm into the nest, showed that peripheral males are capable of fertilizing eggs. I conclude that peripheral males are engaged in an opportunistic alternative mating tactic involving sperm cosnpetition. More than half the observed females bred polyandrously, some mating with up to three males, This was the result of amplexing males dismounting between nesting sessions, and males displacing one another from amplexus. / Andrew Chakane 2018

No description available.

Salamander courtship coordinates the exchange of gametes. Plethodontids have evolved an elaborate means by which this is done. Throughout the family Plethodontidae a tail-straddling walk is performed to orchestrate the transfer of sperm. Typically this behavior is linear, however in the genus Aneides there are exceptions. In the genus Aneides there are two species that have a circular tail-straddling walk; others perform the highly conserved linear tail-straddling walk. I observed courtship in three species of Aneides and used accounts of others to discern which members possessed circular tail-straddling walk and used a phylogeny to map the courtship characters found in the courtships of the members of the tribe plethodontini. / Graduation date: 2003