Inaug.-Diss.--Heidelberg. / Lebenslauf. "Benutzte literatur": p. [21]-22.

Thesis (Ph. D.)--University of Chicago, Dept. of Ecology and Evolution. / Includes bibliographical references. Also available on the Internet.

Thèse--Université de Strasbourg. / "Index bibliographique": p. 483-497.

Inaug.-diss.--Bonn. / Lebenslauf. "Literaturangabe": p. [28]-29.

Inaug.-diss.--Göttingen. / Lebenslauf. "Verzeichnis der benutzten literatur": p. 26-27.

The study of skeletal differences between males and females has rarely taken into account the physical change in hard tissue characteristics with the onset of advanced age. Anatomical change through degenerative modification may pose a challenge when diagnosing the sex of an unknown individual, especially if age is unknown. The aim of this study was to establish whether sexual dimorphism changes with age. This issue was addressed by using three types of procedural analyses. Firstly, standard measuring techniques were utilized to determine sex from 593 individuals. Visual (morphological) assessment was then performed on 608 individuals using sexually dimorphic traits in the distal humerus and pelvis. Lastly, over 300 individuals were analyzed with geometric morphometries using four locations on the postcranial skeleton. Younger females and males (50 years of age and younger) were then compared to older individuals (over 50 years of age) to determine if sexual dimorphism was increasing or decreasing with the onset of age. Long bone measurements of the postcranial skeleton increased with the onset of age in the most osteoporotic sample (South African white females). Males exhibited an increase in size, mainly in the knee and elbow joints, and black females remained static in their measurements with age. Older white females especially can sometimes incorrectly be misclassified as males. Visual techniques indicated that all populations have similar non-metric morphology in the distal humerus and pelvis. Classification accuracies in females decreased when viewing the distal humerus, indicating a decrease in sexual dimorphism at this location. Females appeared static in their pelvic morphology with the onset of age. Males remained sexually dimorphic throughout life in the humerus and pelvis. Geometric morphometries showed that the morphology of the distal humerus is sexually dimorphic, and does not change with age. Morphometries also confirmed the marked sexual dimorphism in the pelvis, and showed virtually no change in sexual dimorphism when comparing young to old groups. / Thesis (PhD)--University of Pretoria, 2009. / Anatomy / Unrestricted

Chez les plantes à fleurs, la gynodioécie -- système dans lequel coexistent des individus femelles et des individus hermaphrodites -- est le système de reproduction le plus commun après l'hermaphrodisme. La question de l'évolution et surtout du maintien de la gynodioécie et du polymorphisme génétique sous-jacent a intrigué les chercheurs depuis le 19e siecle. Aujourd'hui, les grands principes de son évolution sont posés mais beaucoup de zones d'ombres persistent. Durant ma thèse, j'ai exploré trois aspects de la gynodioécie en utilisant une approche expérimentale chez l'espèce Silene nutans et une approche théorique. Je me suis en premier lieu intéressée au déterminisme génétique de la gynodioécie grâce à la réalisation de croisements contrôlés qui m'ont permis de montrer que le déterminisme génétique du sexe était cytonucléaire, c'est à dire contrôlé par plusieurs gènes de stérilité mâle cytoplasmique (CMS) et plusieurs restaurateurs nucléaires de fertilité. En parallèle, j'ai porté une attention particulière aux plantes gynomonoïques -- celles où coexistent sur le même pied des fleurs pistillés (femelles) et des fleurs parfaites (hermaphrodites) -- fréquentes chez Silene nutans comme chez d'autres espèces gynodioïques. J'ai montré que les caractéristiques reproductrices et florales de ce troisième phénotype sexuel étaient souvent intermédiaires entre celles des femelles et des hermaphrodites mais pouvaient dépendre de la proportion de fleurs pistillées sur la plante. Par ailleurs et contrairement à ce qui avait été suggéré, la plasticité du phénotype gynomonoïque s'est révélée être relativement réduite, suggérant un déterminisme génétique dont la caractérisation est encore en cours. La troisième partie de ma thèse a été motivée par les preuves récentes d'hétéroplasmie -- coexistence de différents génomes mitochondriaux au sein d'un individu -- et de la transmission occasionnelle du génome mitochondrial par le pollen chez Silene vulgaris. J'ai montré théoriquement que la présence d'un gène de stérilité mâle cytoplasmique favorisait l'évolution de la fuite paternelle de mitochondries. J'ai également vérifié expérimentalement l'hérédité mitochondriale chez Silene nutans par le génotypage des descendances de croisements contrôlés. / In flowering plants, gynodioecy -- a system in which females and hermaphrodites coexist within populations -- is the most common sexual system after hermaphroditism. The evolution and maintenance of gynodiocy and its underlying polymorphism have puzzled evolutionary biologists since the 19th century. The main principles of its evolution are well known but some points remain vague. During my PhD, I explored three aspects of gynodioecy using an experimental approach in the species Silene nutans and a theoretical approach. First, I studied the genetic determination of gynodioecy using controlled crosses that showed that the genetic determination of sex was cytonuclear, i.e. controlled by several cytoplasmic male sterility (CMS) genes and several nuclear restorers of fertility. Second, I focused on gynomonoecious plants -- those that carry both pistillate (female) flowers and perfect (hermaphrodite) flowers -- that are frequently found in Silene nutans as in other gynodioecious species. I showed that the floral and reproductive traits of this third sex phenotype were often intermediate between those of females and hermaphrodites but varied with varying proportions of pistillate flowers on the plant. Contrary to what was previously thought, the plasticity of the gynomoneocious phenotype was found to be limited, suggesting a genetic determination whose characterization is still in progress. The third part of my PhD was motivated by recent evidences of heteroplasmy -- the coexistence of different mitochondrial genomes within an individual -- and occasional transmission of the mitochondrial genome through pollen in Silene vulgaris. I showed theoretically that the occurrence of a cytoplasmic male sterility gene can favor the evolution of paternal leakage of mitochondria. I also investigated mitochondrial inheritance in Silene nutans by genotyping progenies from controlled crosses.

Sex determination among reptiles is a very variable matter across it's taxa. We meet there temperature sex determination and genotypic sex determination with many independent transitions between them. It is a group suitable to study evolution of sex determination, sex chromosomes and sex determination genes. Rare cases of sex reversal caused by extreme incubation temperature or exogenous hormones have been reported in recent years. In case of Acrodont lizard, Pogona vitticeps, was reported sex reversal caused by high incubation temperatures. Our purpose was to repeat the experiment, mainly due to insufficient conclusiveness of used methods. We wanted to expand the experiment by hormonal reversal, studying persistence of sex reversal to maturity and fertility of reversed individuals. We managed successfully to demonstrate sex reversal in both treatments by histological examination. Individuals with discordant phenotypic and genotypic sex were breed till one year of life, which demonstrate persistence of reversal. Our outcomes are concordant with most recent work on this species and show full functional phenomenon of sex reversal with reptiles, which studying could contribute to our understanding of evolution of sex determination.