The critically endangered blue-eyed black lemur (Eulemur flavifrons) is one the leaststudied day active lemurs because of the recent rediscovery and limited distribution. This thesis examined the habitat use, reproductive parameters and the population viability of the blue-eyed black lemur population at Ankarafa Forest, Sahamalaza-Iles Radama National Park, Madagascar. The main aim was to gather fundamental information on the natural history of the blue-eyed black lemur and to propose conservation approaches for both the species and its habitat. Data were collected over 14 month-period between 2006 and 2008. Six groups of the blue-eyed black lemur were studied, four of which were collared and two uncollared. Ankarafa Forest, the largest forest blocks of the Sahamalaza-Iles Radama National Park, is dominated mainly by Mangifera indica, Garcinia pauciflora, Sorindeia madagascariensis, Grangeria porosa, Bambou sp. and Mascarenhasia arborescens species. The forest is vulnerable to degradation by both anthropogenic activities and abiotic factors. The population density of the blue-eyed black lemur at Akarafa Forest was estimated to be 97.3 individuals km-², with group size ranging from 4 to 11 individuals. The home range use and day path length of the blue-eyed black lemur varied seasonally. The lemur occupied a larger home range in the dry season than in the wet season. The age of first reproduction in the blue-eyed black lemurs is about 3 years. They bear offspring seasonally (late August-October), all adult females in groups bred and females produce singletons offspring. Females were dominant over males. The sex-ratio at birth was male-biased but not significantly different from 1:1. Females were the primary caretakers of infants but group members other than the mother also provided alloparental care. For the first 3 weeks of life, infants were carried constantly on their mothers’ bellies. Infants developed independent locomotion and fed on solid food by 10 weeks. Increased probability of extinction, as shown by population viability models of the blue-eyed black lemur population, is affected by various of their reproductive parameters. However, these do not account for changes in their primary habitat forest. The latter is under increased human pressure and continues to decline in area. Education awareness and community involvement are required if the habitat and the blue-eyed black lemur are to survive. Findings of this study serve not only important data to understand the life history of the blue-eyed black lemur but also suggest conservation approaches for both the species and its natural habitat. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2009.

No description available.

<p>Female social dominance over males is unusual in mammals, yet characterizes most Malagasy lemurs, which represent almost 30% of all primates. Despite its prevalence in this suborder, both the evolutionary trajectory and proximate mechanism of female dominance remain unclear. Potentially associated with female dominance is a suite of behavioral, physiological and morphological traits in females that implicates ‘masculinization’ via androgen exposure; however, relative to conspecific males, female lemurs curiously show little evidence of raised androgen concentrations. In order to illuminate the proximate mechanisms underlying female dominance in lemurs, I observed mixed‐sex pairs of related Eulemur species, and identified two key study groups ‐‐ one comprised of species expressing female dominance and, the other comprised of species (from a recently evolved clade) showing equal status between the sexes (hereafter ‘egalitarian’). Comparing females from these two groups, to test the hypothesis that female dominance is an expression of an overall masculinization of the female, I 1) characterize the expression of female dominance, aggression, affiliation, and olfactory communication in Eulemur; 2) provide novel information about the hormonal and neuroendocrine correlates associated with the expression of female dominance; 3) investigate the activational role of the sex-steroid hormones in adult female Eulemur using seasonal correlates of hormonal and behavioral change; and 4) examine the specific role of estrogen in the regulation and expression of sex-reversed female behavior in these species. In doing so I highlight significant behavioral and physiological differences between female-dominant and egalitarian Eulemur and show that female dominance is associated with a more masculine behavioral and hormonal profile. I also suggest that these behavioral and hormonal differences may be the result of fundamental differences in the biosynthetic pathway associated with estrogen production. Moreover, I assert that these putative physiological differences could provide a parsimonious proximate mechanism explaining the evolution of female dominance and its subsequent relaxation in egalitarian Eulemur species.</p> / Dissertation

Zugl.: Giessen, Univ., Diss., 2009

No description available.

No description available.

No description available.

L'ontogenèse des comportements alimentaires du primate Eulemur fulvus a été étudiée dans une forêt sèche de l'île de Mayotte (Archipel des Comores) en relation avec les influences sociales émanant de la mère et des autres individus du groupe et les contraintes environnementales. Elle se construit en 4 phases : (1) de la naissance au troisième mois, le jeune explore son environnement et ingère sa première nourriture solide ; (2) les quatrièmes et cinquièmes mois correspondent à son sevrage alimentaire et social ; (3) les deux mois suivants, il acquiert les rythmes alimentaires de sa mère ; (4) entre son dixième et douzième mois d'existence, il est socialisé et son régime alimentaire est comparable à celui de l'adulte. Mais le jeune ne reproduit pas uniquement le régime alimentaire de sa mère. Dès les premiers stades de son alimentation végétale, il ingère des aliments qu'elle ne consomme pas et forge sa propre expérience individuelle. Après son sevrage, il recherche une nourriture riche en protéines (essentiellement des fleurs). De son côté, la mère augmente ses prises alimentaires (dont celles des fleurs) pendant les premiers mois de lactation. Ainsi, les variations saisonnières des disponibilités alimentaires semblent déterminer la période des naissances et du sevrage (saison des pluies), ce qui maximiserait les chances de survie du jeune. De même, la flexibilité potentielle des comportements alimentaires du jeune pourrait expliquer la capacité d'adaptation rapide de cette espèce à de nouveaux environnements.

No description available.

Adipositas ist eine polymorphe chronische Erkrankung mit epidemischer Prävalenz. Im katabolen Leptin-Melanocortin-Signalweg ist das Proopiomelanocortin Gen (POMC) ein zentrales Element, das bei Dysfunktion massive Adipositas bewirken kann. Auch eine kürzlich identifizierte intragenische Methylierungsvariante des POMC wurde mit Adipositas assoziiert und deutet somit auf eine mögliche epigenetische Modulation des Gewichtsphänotyps hin. Zur Aufklärung der Relevanz, Stabilität und Entwicklung dieser epigenetischen Modifikation wurden die Funktionalität, Ontogenese und Phylogenese der POMC DNA-Methylierung untersucht. In vitro Analysen zeigten DNA-Methylierungsabhängige Promoteraktivität beider CpG-Inseln (CGIs) des POMC. Diese hier erstmals beschriebene Transkriptionsaktivität der intragenischen CGI weist auf einen alternativen Promoter des POMC hin. Hinsichtlich der Ontogenese konnten in Mensch und Maus postnatal stabile DNA-Methylierungsmuster mit interindividueller Konservierung für beide CGIs des POMC identifiziert werden. Zusätzlich erwiesen sich Gewebeunabhängigkeit der DNA-Methylierungsmuster und ihre pränatale Ausbildung zwischen dem Blastocystenstadium und der frühen Organogenese in der Maus. Die POMC DNA-Methylierungsmuster upstream des Exon3 unterscheiden sich in Mensch und Maus. Der mögliche Einfluss von primatenspezifischen Alu-Elementen im Intron2 des POMC hierauf wurde in verschiedenen Primatenfamilien analysiert. Die Ergebnisse zeigen eine bedingte Assoziation der Alu-Elemente mit der DNA-Methylierung in der entsprechenden Region, lassen jedoch auch weitere Einflussfaktoren vermuten. Insgesamt zeigt diese Arbeit, dass die POMC DNA-Methylierung artspezifisch konserviert ist und in der frühen Embryogenese, vermutlich Alu-abhängig, ausgebildet wird. Dabei könnten stochastische Variationen der DNA-Methylierung die POMC-Aktivität beeinflussen und somit das Risiko für Adipositas erhöhen. / Obesity is a polymorphic chronic disease with epidemic prevalence. Within the catabolic leptin-melanocortin signaling pathway pre-proopiomelanocortin (POMC) is a pivotal element. Dysfunction of POMC, e.g. due to mutations, can cause severe obesity. Moreover, a recently identified intragenic methylation variant of POMC was found to be associated with obesity. Therefore, this indicates potential epigenetic modulation of the weight phenotype. To gain further insight into the relevance, stability, and origin of this epigenetic modification, the functionality, ontogenesis, and phylogenesis of the POMC DNA methylation patterns were analyzed. In vitro analyses revealed DNA methylation-dependent promoter activity of both CpG islands (CGIs) of POMC. Thereby, the intragenic CGI was identified as a potential alternative promoter of POMC, which has not been described before. Regarding the ontogenesis, postnatally stable POMC DNA methylation patterns with interindividual conservation were detected for both CGIs in humans and mice. In addition, it was observed that the POMC DNA methylation patterns are non-tissue-specific, stable upon long time administration of a high fat diet, and develop prenatally between the blastocystal stage and the early organogenesis. The POMC DNA methylation pattern upstream of exon3 differs in humans and mice. A possible influence of primate-specific Alu elements within the intron2 region of POMC was analyzed in various primate families. Results evince a partial association of the Alu elements with the DNA methylation pattern in this particular region, but also suggest an influence of additional factors. Overall, this work demonstrates that DNA methylation of the POMC locus is species-specific highly conserved, and that it is established during early embryogenesis, possibly Alu-triggered. In the course of this, stochastic variances of the POMC DNA methylation might influence the POMC activity and consequently alter the risk to develop obesity.