MGS / Institute for Gender and Youth Studies / See the attached abstract below

Gaining a good understanding of marine turtle mating systems is fundamental for their effective conservation, yet there are distinct gaps in our knowledge of their breeding ecology and life history, owing largely to the difficulty in observing these highly mobile animals at sea. Whilst multiple mating by females, or polyandry, has been documented in all marine turtle species, the fitness consequences of this behaviour have not been fully investigated. Furthermore, male mating patterns, operational sex ratios and the number of males contributing to breeding populations are poorly understood, impeding accurate assessments of population viability. In this thesis, I use molecular-based parentage analysis to study, in detail, the genetic mating system of two green turtle (Chelonia mydas) populations. In the focal population in northern Cyprus, I show that, despite exhibiting a strongly female-biased hatchling sex ratio and contrary to our expectations, there are at least 1.3 breeding males to every nesting female. I go on to assess the breeding frequency of male turtles in the population and determine that males do not breed annually at this site, demonstrating that the observed relatively equal sex ratio of breeders is not the result of a few males mating every year, but that the number of breeding males in the population is greater than expected. I show that 24% of nesting females in the population produce clutches with multiple paternity, but do not detect any fitness benefits to polyandrous females, and discuss the potential role of sexual conflict in influencing female mating decisions. Finally, I reveal a high frequency of multiple paternity in green turtle clutches on Ascension Island, one of the largest green turtle rookeries in the world, and discuss possible causes of variation in the level of polyandry among marine turtle populations. The results presented here shed new light on aspects of marine turtle mating systems that are challenging to study, and illustrate the value of molecular data, not only in describing mating patterns, but in elucidating aspects of life history and behaviour that would otherwise be very difficult to ascertain.

In this dissertation, I report new information that is necessary for future mating system studies in a little studied species, the marbled salamander (Ambystoma opacum). I studied female mating behavior, sexual selection, and the consequences of polyandry for individual females and salamander populations. I also compared the performance of several statistical approaches for analyzing genetic mating system data. The first chapter summarizes the characteristics of several novel microsatellite DNA loci as well as cross-amplified loci for marbled salamanders and mole salamanders that may be used for future studies. In the second chapter, I report estimates of sire number for 13 marbled salamander clutches based on microsatellite data from 32 hatchlings per clutch. Females mated with as many as three different males as indicated by conservative techniques. Less than half of females mated with multiple males. Based on comparative analyses, I recommend the parental reconstruction approach with the computer program GERUD for assessing multiple paternity. The third chapter describes an experiment designed to study sexual selection. As expected, in breeding mesocosms, the potential for sexual selection was much higher for males than for females. Size was unrelated to variance in male reproductive fitness. Only opportunity for selection and Morisita’s index conformed to theoretical expectations of the relationship between operational sex ratio and the potential for sexual selection among males. Because opportunity for selection has intuitive links to formal sexual selection theory, I recommend its continued use. In the fourth chapter, I compared polyandrous and monandrous females to explore the potential fitness consequences of multimale mating. No fitness measure at the egg or hatchling stage (clutch size, hatching success, hatchling size, etc.) differed between the two types of clutches. Size of metamorphs was not different, but polyandrous clutches had significantly higher survival to metamorphosis. In the fifth chapter, I analyzed effects of increased polyandry and male availability on genetic diversity, effective population size (Ne), and fitness of experimental populations. Although no analyses were significant, some effects were moderate to high in size. Ne was higher when estimated from hatchlings than with metamorphs.

The protection of species is one major focus in conservation biology. The basis for any management concept is the knowledge of the species autecology. In my thesis, I studied the life-history traits and population dynamics of the endangered Lesser Spotted Woodpecker (Picoides minor) in Central Europe. Here, I combine a range of approaches, from empirical investigations of a Lesser Spotted Woodpecker population in the Taunus low mountain range in Germany, the analysis of empirical data and the development of an individual-based stochastic model simulating the population dynamics.<br><br> In the field studies I collected basic demographic data of reproductive success and mortality. Moreover, breeding biology and behaviour were investigated in detail. My results showed a significant decrease of the reproductive success with later timing of breeding, caused by deterioration in food supply. Moreover, mate fidelity was of benefit, since pairs composed of individuals that bred together the previous year started earlier with egg laying and obtained a higher reproductive success. Both sexes were involved in parental care, but the care was only shared equally during incubation and the early nestling stage. In the late nestling stage, parental care strategies differed between sexes: Females considerably decreased feeding rate with number of nestlings and even completely deserted small broods. Males fed their nestlings irrespective of brood size and compensated for the females absence. The organisation of parental care in the Lesser Spotted Woodpecker is discussed to provide the possibility for females to mate with two males with separate nests and indeed, polyandry was confirmed.<br><br> To investigate the influence of the observed flexibility in the social mating system on the population persistence, a stochastic individual-based model simulating the population dynamics of the Lesser Spotted Woodpecker was developed, based on empirical results. However, pre-breeding survival rates could not be obtained empirically and I present in this thesis a pattern-oriented modelling approach to estimate pre-breeding survival rates by comparing simulation results with empirical pattern of population structure and reproductive success on population level. Here, I estimated the pre-breeding survival for two Lesser Spotted Woodpecker populations on different latitudes to test the reliability of the results.<br><br> Finally, I used the same simulation model to investigate the effect of flexibility in the mating system on the persistence of the population. With increasing rate of polyandry in the population, the persistence increased and even low rates of polyandry had a strong influence. Even when presuming only a low polyandry rate and costs of polyandry in terms of higher mortality and lower reproductive success for the secondary male, the positive effect of polyandry on the persistence of the population was still strong.<br><br> This thesis greatly helped to increase the knowledge of the autecology of an endangered woodpecker species. Beyond the relevance for the species, I could demonstrate here that in general flexibility in mating systems are buffer mechanisms and reduce the impact of environmental and demographic noise. / Der Schutz von Arten ist eine der Hauptaufgaben des Naturschutzes. Für die Erstellung von Schutzkonzepten sind Informationen zur Autökologie der Zielart notwendige Voraussetzung. Der Kleinspecht (Picoides minor) ist in vielen Teilen seines Verbreitungsgebietes bestandsbedroht, das Wissen zur Biologie und Verhalten der Art ist jedoch lückenhaft. Ziel meiner Arbeit war es daher, demographische Parameter der Populationsdynamik des Kleinspechts zu erfassen, die als Grundlage für Populationsgefährdungsanalysen benötigt werden. Da Untersuchungen in Schweden eine gewisse Flexibilität im Paarungssystem des Kleinspechts zeigten, sollte darüber hinaus das Paarungssystem und sein Einfluss auf die Persistenz der Population untersucht werden.<br><br> Die Arbeit umfasste eine Reihe von methodischen Ansätzen, von empirischen Untersuchungen an einer Kleinspechtpopulation im hessischen Vordertaunus über die Aufbereitung von empirischen Daten bis hin zur Entwicklung und Auswertung eines stochastischen individuenbasierten Modells zur Simulation der Populationsdynamik.<br><br> Die Ergebnisse der empirischen Untersuchung zeigten eine Abnahme des Reproduktionserfolgs mit fortschreitendem Legebeginn. Die Zusammensetzung der Nestlingsnahrung ließ vermuten, dass dies durch eine Verschlechterung der Nahrungsversorgung begründet war. Paartreue war bei der Reproduktion von Vorteil, da Individuen, die schon im vorherigen Jahr zusammen gebrütet hatten, einen früheren Legebeginn und damit einen höheren Fortpflanzungserfolg aufwiesen als neu formierte Paare. Beide Geschlechter investierten in die Brutpflege, jedoch war die Aufteilung nur während der Bebrütung der Eier und in der ersten Hälfte der Nestlingsperiode gleichmäßig. In der späten Nestlingsperiode konnten geschlechtsspezifische Strategien im elterlichen Investment identifiziert werden: die Weibchen verringerten die Versorgungsrate in Abhängigkeit des Wertes der Brut - gemessen in der Zahl der Nestlinge - und gaben die Versorgung kleiner Bruten ganz auf. Die Männchen dagegen kompensierten dieses Verhalten, so dass auch von den Weibchen verlassene Bruten erfolgreich waren. Interessanterweise konnte mehrmals die Verpaarung von einem Weibchen mit zwei Männchen beobachtet werden. Das Auftreten dieses polyandrischen Paarungssystems wird in der Arbeit als Resultat der Aufteilung der Brutpflege diskutiert. <br><br> Die bestätigte Flexibilität im Paarungssystem könnte Einfluss auf die Persistenz der Population haben. Die Persistenz von Populationen kann jedoch nicht empirisch gemessen werden. Daher entwickelte ich ein individuen-basiertes stochastisches Modell zur Simulation der Populationsdynamik des Kleinspechts, dass auf den empirischen Daten basiert. Allerdings fehlten Überlebensraten der ausgeflogenen Jungvögel, die im Feld nicht ermittelt werden kann. Daher testete ich hier eine Methode, die durch den Vergleich von Simulationsergebnissen mit eigenen empirischen Daten zur Populationsstruktur und zum Reproduktionserfolg auf der Ebene der Gesamtpopulation die Überlebensrate der Jungvögel abschätzt. Die Überlebensraten wurde zusätzlich für eine Population des Kleinspechtes ermittelt, deren Datengrundlage aus Freilandstudien in Schweden stammten. Durch den Vergleich der Raten für die beiden Populationen konnte die Aussagefähigkeit des Modells und die Güte der Abschätzungen untersucht werden. Im letzten Teil meiner Arbeit nutzte ich das Modell schließlich, um die Auswirkungen des Paarungssystems auf die Überlebensfähigkeit der Population zu untersuchen. Im Modell konnte ein Weibchen polyandrisch sein, wenn es gute Brutbedingungen hatte und das Geschlechterverhältnis zum Männchen hin verschoben war. Zusätzlich variierte ich die Wahrscheinlichkeit, dass unter diesen Umständen Polyandrie auftritt. Im Model wurden 3 Szenarien getestet: (i) strenge Monogamie, (ii) gelegentliche Polyandrie und (iii) gelegentliche Polyandrie unter der Annahme von Kosten für das sekundäre Männchen in Form von höherer Mortalität und geringerem Reproduktionserfolg. Es zeigte sich, dass selbst sehr geringe Polyandrieraten und die Annahme von Kosten noch einen deutlichen positiven Einfluss auf die Persistenz der Population ausüben. Die Flexibilität im Paarungssystem dient damit als Puffermechanismus gegen demographisches Rauschen und Umweltrauschen. <br><br> Diese Arbeit trät dazu bei, die Autökologie des Kleinspechts besser zu verstehen und ist damit wichtige Grundlage für Schutzkonzepte in Mitteleuropa. Über die artspezifische Bedeutung hinaus, leistet die Arbeit einen Beitrag zur Untersuchung von Methoden zur Abschätzung fehlender demographischer Parameter sowie zur Identifizierung von Puffermechanismen. Eine wichtige Schlussfolgerung meiner Arbeit ist es, dass die Flexibilität artspezifischen Verhaltens in zukünftigen Populationsgefährdungsanalysen integriert werden sollte, um die Qualität von Prognosen zur Persistenz von Populationen zu verbessern.

A key feature of social Hymenoptera is the division of labor in reproduction between one or a few fertile individuals – the queen(s) – and many sterile nestmates that function as helpers – the workers. The reproductive altruism of workers has long been considered as one of the most important paradox of Evolution. Today, kin selection (Hamilton 1964a,b) is recognized as a prime selective force for the evolution reproductive altruism in Hymenoptera. Hamilton’s kin selection theory states that workers may benefit helping relatives reproduce as long as the relatives they aid share a higher than average proportion of their genes with the workers and effectively pass on copies of the workers' genes to the next generation. Relatedness between colony members is therefore pivotal in kin selection theory, because it directly influences the benefits from indirect fitness. In social Hymenoptera, within-colony relatedness is usually high, because of the haplodiploid sex determinism system. However, several factors of the breeding system are known to affect the colony genetic structure and, hence, the workers’ indirect inclusive fitness: the number of breeders, their genetic relationships and their relative contribution to the reproduction. On the other hand, dispersal strategies influence the population genetic structure, which in turn may result in different interaction patterns between members from neighboring colonies. Despite its central role in the evolution of cooperation and reproductive altruism in animals, kin selection also predicts conflicts between colony members. Because the individuals from a colony are not genetically identical, their reproductive interests may be different (Trivers 1974). These conflicts are diversified, both regarding their actors and their causes (Trivers & Hare 1976; Bourke & Franks 1995; Keller 1995; Chapuisat & Keller 1999b; Keller & Reeve 1999; Sundström & Boomsma 2001). The first part of this work deals with the population genetic structure, mating system and dispersal strategies of two Pheidole ants, the Mediterranean ant Pheidole pallidula and the Mojave Desert ant Pheidole tucsonica. Chapter 1 investigates the population genetic structure, the breeding system, the colony kin composition and the colony genetic structure of the Mediterranean ant P. pallidula. This study was performed by using highly polymorphic DNA microsatellite marker loci. The results show that a single, unrelated male inseminates each queen. Colonies are monogynous (i.e. headed by one reproductive queen) or polygynous (i.e. headed by 2 to 4 functional queens). Moreover, they are genetically differentiated and form a population exhibiting significant isolation-by-distance, suggesting that some colonies originate through budding. Chapter 2 reports cross-species amplifications of microsatellite markers developed for the ant P. pallidula on 13 ant species belonging to the sub-family Myrmicinae. Moreover, levels of genetic diversity within a colony, as well as relationship among colonies are studied for the black ant Pheidole tucsonica. Chapter 3 characterizes the level of inter-nest aggression, the spatial distribution and the genetic structure of a P. tucsonica population. The results show that inter-colony aggression varies from none to “all out” fights and that it is largely non-transitive. No effect of geographical distance or genetic structure on inter-nest aggression levels is detected. Moreover, genetic data reveal high rates of polygyny and/or polyandry. Overall, these results do not support the idea of a simple mechanism of nestmate recognition through queen or worker-produced pheromones or environmental cues. The second part of this work is devoted to the queen-queen conflict over reproduction, and the queen-workers conflict over sex allocation in P. pallidula. Chapter 4 is a detailed analysis on the partitioning of reproduction among queens in polygynous colonies of the species. Our results show a significant departure from equal contribution of queens to reproductive female, male and worker production. Reproductive skew is greater for male production than for queen and worker production. There is no relationship between the magnitude of the reproductive skew and (i) the number of reproductive queens per colony, (ii) their relatedness and (iii) the overall colony productivity, some of the factors predicted to influence the extent of reproductive skew. Finally, this study reveals a trade-off in the relative contribution of nestmate queens to reproductive female and worker production. The queens contributing more to reproductive female production contribute significantly less to worker production. To our knowledge, such a trade-off is shown for the first time in the Formicidae. Chapter 5 focuses on queen-workers conflict over sex allocation. Colonies of the Mediterranean ant P. pallidula show a strong split sex ratio, with 85% colonies producing more than 80% sexuals of one sex. Genetic analyses reveal that this species has an unusual breeding system, with colonies being headed by a single or a few unrelated queens. As expected in such a breeding system, our results show no variation in relatedness asymmetry between monogynous (single queen per colony) and polygynous colonies. Nevertheless, sex allocation is tightly associated with the breeding structure, with monogynous colonies producing a male-biased brood and polygynous colonies almost only females. In addition, sex allocation is closely correlated with colony total sexual productivity. Overall, our data show that when colonies become more productive (and presumably larger) they shift from monogyny to polygyny and from male production to female production, a pattern that has never been reported in social insects so far. A new explanation based on the concept of the “tragedy of the commons” is proposed to explain the strong sex ratio specialization observed in P. pallidula and in other species characterized by facultative polygyny. Chapter 6 investigates the relationship between the breeding system (monogynous vs. polygynous colonies) and the biosynthesis rate of juvenile hormone. Previous works in P. pallidula showed (i) that maternal effects induced by hormones and/or other compounds transferred to the eggs could influence the caste fate of female eggs and (ii) that sex specialization is tightly associated with the breeding structure (monogynous colonies produce a male-biased brood and polygynous colonies almost only females - Chapter 5). This study reveals a strong relationship between the biosynthetic rate of juvenile hormone (JH) production and the breeding system. Because in this species the breeding structure is closely associated with colony sex ratio, we propose that the rate of JH in queens could be a critical parameter in colony sex ratio determination. Queens of P. pallidula would exert partial control over sex ratio by laying different proportions of worker-destined eggs and queen-destined eggs according to the structure monogynous or polygynous of their colony. To conclude, some perspectives for future research on the different topics presented in this work are suggested. / Doctorat en Sciences / info:eu-repo/semantics/nonPublished

Cette thèse porte sur deux espèces de grands requins, le requin bouledogue Carcharhinus leucas et le requin tigre Galeocerdo cuvier. Les objectifs sont d'étudier la structure génétique de leurs populations, la taille efficace des populations identifiées et les modes de reproduction de ces deux espèces. Une différenciation génétique importante a été identifiée entre les populations de requin bouledogue de l'Ouest de l'océan Indien et de l'Ouest du Pacifique, reflétant soit une absence de flux de gènes contemporains, soit des flux de gènes uniquement assurés par les mâles. À l'inverse, les populations de requin tigre de ces deux régions sont homogènes génétiquement. Une plus faible diversité génétique a été identifiée chez le requin tigre que chez le requin bouledogue, peut-être liée à une diminution forte des effectifs datant de moins de 3 000 ans. Autour de La Réunion, les populations des requins bouledogue et tigre suivent des dynamiques différentes, liées à leurs modes de reproduction. Chez le requin bouledogue, les individus semblent fidèles à des zones côtières particulières (philopatrie) pour s'accoupler et/ou mettre bas, et les portées sont fréquemment issues de plusieurs pères (polyandrie). À l'inverse, les zones d'accouplement et de mise bas du requin tigre restent mal connues, et cette espèce semble exclusivement monoandre, caractéristiques liées à sa nature semi-océanique. Ces travaux montrent les capacités de dispersion importantes de ces deux espèces. Leurs populations présentent des dynamiques différentes induisant une vulnérabilité différente aux pressions anthropiques. / This PhD thesis focuses on two large shark species, the bull shark Carcharhinus leucas and the tiger shark Galeocerdo cuvier. The aims are to study the genetic structuring of their populations, the effective population size of the delimited populations and the reproductive modes of both species. A strong genetic differentiation was highlighted between bull shark populations from the Western Indian Ocean and the Western Pacific, due to either an absence of contemporary gene flow or to an absence of female gene flow only. On the opposite, tiger shark populations seem genetically homogenous, with important genetic connectivity between both regions. Within each region, no genetic differentiation among localities was highlighted for both species. A weaker genetic diversity was identified for the tiger shark, probably linked to the occurrence of a recent bottleneck occurring less than 3,000 years ago. Around Reunion Island, bull and tiger shark populations present different dynamics, linked to their reproductive modes. Bull shark individuals from both sexes seem to exhibit some fidelity to specific coastal sites (philopatry) to mate and/or deliver embryos, and litters are frequently issued from several fathers (polyandry). On the opposite, mating and pupping areas of the tiger shark remain poorly known, and this species seems exclusively monoandrous, probably linked to its semi-oceanic nature.This work highlights the high dispersal abilities of both species. Their populations present different dynamics, leading to different sensitivities to anthropogenic pressures. These results point out the need to adopt management plans specific to each species

Les insectes sociaux représentent le paradigme de la vie coopérative dans le règne animal. Ceci repose sur l’existence d’une division des activités reproductrices entre des individus reproducteurs (les reines et les mâles) et une majorité d’ouvrières sacrifiant leurs propres potentialités reproductives pour assurer l’essentiel des tâches logistiques nécessaires à l’essor des sociétés. Chez les Hyménoptères sociaux, l’analyse comparative des stratégies de reproduction révèle que la structure monogyne (une reine par société) et monandre (un seul accouplement par reine) est l’état ancestral des sociétés. Cette structure favorise une corrélation génétique élevée entre les ouvrières et le couvain qu’elles élèvent et, par conséquent, leur succès reproductif global (inclusive fitness). Cependant, un nombre croissant d’études génétiques montre que la structure des sociétés peut fortement s’éloigner de ce pattern. Ceci est particulièrement manifeste chez les fourmis, lesquelles présentent un très large polymorphisme social se traduisant par une grande variabilité du nombre de femelles reproductrices au sein des sociétés. Les formicidés sont également remarquables par la diversité de leurs modes de reproduction. Cette diversité concerne la fréquence des accouplements (monandrie/polyandrie) ou encore l’exploitation conditionnelle des modes de reproductions sexuée et asexuée. Chez quelques espèces, les futures reines sont en effet produites par parthénogenèse (elles sont des quasi-clones de leur mère), alors que les ouvrières sont issues d'une reproduction sexuée classique. Cette stratégie exceptionnelle permet aux reines d'accroître le taux de transmission de copies de leurs gènes dans la descendance, tout en conservant les bénéfices d'une diversité génétique dans la force ouvrière. Cette grande diversité de structures sociales et de modes de reproduction suggère l’action de nombreuses pressions sélectives. Les travaux réalisés dans le cadre de cette thèse de doctorat visent à déterminer les facteurs responsables du large polymorphisme social et des nombreux modes de reproduction observés chez les fourmis désertiques du genre Cataglyphis. Ils sont articulés autour de deux axes principaux. <p>Les analyses phylogénétiques montrent que la polyandrie est ancestrale au sein du genre Cataglyphis. Le premier axe de ce travail a pour but d’étudier les causes évolutives justifiant le maintien d’un tel système de reproduction au sein de ce genre. Ce travail porte sur les avantages d’une diversité génétique accrue parmi les ouvrières. Une telle diversité génétique permettrait notamment d'accroître le polymorphisme de taille des ouvrières et l'efficacité de la division du travail [Chapitre 1], ou la résistance aux pathogènes de la force ouvrière [Chapitre 2]. [1] Ce premier travail a été réalisé sur Cataglyphis cursor, une espèce strictement monogyne et polyandre. Les résultats de cette étude révèlent une très grande fidélité des ouvrières à la tâche. Ils montrent l’existence d’une association significative entre la tâche réalisée par une ouvrière et sa lignée paternelle, ainsi qu’entre la taille des ouvrières et la tâche effectuée. [2] Le second travail de cette thèse a été réalisé chez C. mauritanica. Nos résultats montrent que la résistance aux pathogènes diffère entre ouvrières issues de différentes lignées paternelles lorsque ces dernières sont isolées. Curieusement, cette différence s’estompe lorsque les lignées paternelles sont regroupées au sein des sociétés polyandres. Dès lors, la polyandrie permettrait d’homogénéiser l’immunité des sociétés. Nos données montrent cependant que la résistance des ouvrières à Metarhizium anisopliae n’est pas corrélée à la diversité génétique de la colonie ou au nombre d’accouplements des reines.<p>Le second axe de ce travail porte sur les stratégies de reproduction remarquables observées chez les espèces de Cataglyphis appartenant au groupe altisquamis :C. velox, C. mauritanica, C. humeya et C. hispanica. Ces espèces partagent une stratégie unique dans le règne animal, appelée hybridogénèse sociale. L’hybridogénèse classique est un système reproductif dans lequel les parents issus de lignées génétiques distinctes s’hybrident. Alors que les génomes maternels et paternels sont exprimés dans la lignée somatique des descendants, le génome paternel est systématiquement écarté de la lignée germinale. En conséquence, seul le génome maternel est transmis aux générations futures. Dans le schéma d’hybridogénèse sociale reporté dans ces travaux, les reines s’accouplent systématiquement avec un mâle originaire d’une lignée génétique distincte. Elles utilisent la reproduction sexuée pour la production d’une caste ouvrière stérile intégralement hybride (analogue à la lignée somatique) et la reproduction asexuée par parthénogénèse pour la production des castes reproductrices mâles et femelles (analogues à la lignée germinale). Dans ce système, bien que les génomes paternels et maternels soient exprimés dans la caste ouvrière, seul le génome maternel est transmis aux descendants reproducteurs [Chapitre 3]. Le groupe altisquamis est représenté par plusieurs espèces au sein desquelles deux lignées génétiques s’hybrident systématiquement pour la production de la caste ouvrière. Le dernier chapitre de cette thèse [4] est une analyse phylogéographique des espèces de ce groupe dans la péninsule ibérique. Les résultats confirment l’existence d’une seule paire de lignées génétiques au sein de chaque espèce. Ces résultats révèlent également une contradiction entre les marqueurs nucléaires et mitochondriaux traduisant la complexité du système reproductif. Ces travaux soulignent l’ambiguïté des relations phylogéniques entre espèces d’un tel système et discutent de son implication dans la spéciation des espèces hybridogénétiques. <p><p><p>Social insects represent the most extreme form of cooperative life in the animal kingdom. This is based on the existence of a division of reproductive activities between the reproductive individuals (queens and males) and a majority of workers performing all logistical tasks at the expense of their own reproduction. In social Hymenoptera, comparative analysis of reproductive strategies reveals that colonies headed by a single mated queen (monogyny/monoandry) is the ancestral structure of colonies. This structure provides a high genetic correlation between the workers and the brood they raise and, therefore, their overall reproductive success (inclusive fitness). However, an increasing number of genetic studies reveal that the reproductive structure of colonies can strongly differ from this pattern. This is particularly obvious in ants, which have a very large social polymorphism resulting in a large variability in the number of reproductive females within colonies. The Formicidae are also remarkable for the diversity of their modes of reproduction. This diversity relates to mating frequency (monoandry/polyandry) or conditional use of sexual and asexual reproduction. In some species, new queens are produced by parthenogenesis (they are almost clones of their mothers), while the workers arise from a classical sexual reproduction. By using alternative modes of reproduction for queen and worker castes, queens can increase the transmission rate of their genes to their reproductive female offspring while maintaining genetic diversity in the worker population. This high diversity of social structures and modes of reproduction suggests the occurrence of many selective forces. This thesis aimed at determining environmental and genetic factors responsible for the large social polymorphism and the high diversity of reproductive modes display by Cataglyphis desert ants. This thesis is divided into two main parts. <p>Phylogenetic analyses show that polyandry is ancestral across the genus Cataglyphis. The first part of this thesis examines the genetic hypothesis to account for the evolution and maintenance of multiple mating by queen in this genus. This work focuses on the benefits of increased genetic diversity among workers. Such genetic diversity may increase the size polymorphism of the worker force and improve efficiency of the division of labor [Chapter 1] or increase pathogen resistance of the colony [Chapter 2]. In Chapter 1, the genetic hypothesis to enhance efficiency of division of labor was tested on Cataglyphis cursor, a strictly monogynous and polyandrous species. The results reveal a great fidelity in task performance by workers. They reveal a significant association between patriline and task preference: workers belonging to different patrilines differ in their propensity to perform a given task. We also found that worker size is closely associated with task specialization. The second work of this thesis [Chapter 2] was performed in C. mauritanica. Our results show that resistance to pathogens differs between workers from different patrilines when patrilines are raised separately. Surprisingly, this difference disappears when the patrilines are grouped within polyandrous colonies. Therefore, polyandry would standardize the overall resistance of colonies. Consistent with this result, our data show a positive association between the number of matings by the queens and colony resistance to Metarhizium anisopliae. <p>The second part of this thesis expounds the unorthodox reproductive strategies observed in species belonging to the group Cataglyphis altisquamis: C. velox, C. mauritanica, C. hispanica and C. humeya. These species share a unique strategy in the animal kingdom, called social hybridogenesis. Hybridogenesis is a sexual reproductive system, whereby parents from different genetic origin hybridize. Both the maternal and paternal genomes are expressed in somatic tissues, but the paternal genome is systematically excluded from the germ line, which is therefore purely maternal. Consequently, only the maternal genome spread across generations. Here, we report a unique case of hybridogenesis at a social level. Queens mate exclusively with males originating from a different genetic lineage than their own to produce hybrid workers, while they use parthenogenesis to produce the male and female reproductive castes. In consequences, all sterile workers (somatic line) are sexually produced hybridogens, whereas sexual forms (germ line) are clonally produced. Thus, only maternal genes are perpetuated across generations [Chapter 3]. The group C. altisquamis is represented by several hybridogenetic species in which two highly divergent genetic lineages co-occur, despite their constant hybridization. The last chapter of this thesis [Chapter 4] is a phylogeographic analysis of C. altisquamis species in the Iberian Peninsula. Our results confirm the existence of a single pair of genetic lineages within each species. Our results also reveal strong incongruences between nuclear and mitochondrial markers that reflect the reproductive system complexities. These studies reveal phylogenetic ambiguities among these hybridogenetic species and discuss the involvement of such unconventional system in speciation process.<p> / Doctorat en Sciences / info:eu-repo/semantics/nonPublished

Selon la théorie de la sélection de la parentèle, les individus peuvent transmettre des copies de leurs gènes à la génération suivante sans accéder eux-mêmes à la reproduction, mais en aidant des apparentés à augmenter leur propre succès reproductif. Ce concept reste aujourd'hui l'explication la plus probable pour justifier l'évolution de l’altruisme de reproduction dans le règne animal. Les coefficients de corrélations génétiques entre les membres d’un groupe ont une importance capitale, puisqu'ils influencent directement les bénéfices génétiques indirects associés au comportement altruiste. Trois principaux facteurs sont cependant connus pour influencer profondément l'architecture des sociétés: (i) le nombre de reines présentes dans un nid (polygynie), (ii) le nombre d'accouplements des reines (polyandrie), et (iii) l’accouplement entre apparentés (consanguinité).<p>\ / Doctorat en Sciences / info:eu-repo/semantics/nonPublished

The aim of the project was to test female advantages of promiscuous and/or polyandrous mating. Although, previous studies reported improved reproductive success of females copulating with multiple males in many model species, including Eublepharis macularius, this study failed to demonstrate such a benefit of polyandry. Traits reflecting female reproductive success, i.e. the number of produced eggs, egg mass, hatchability, hatchling mass, growth and survival were not influenced by copulation with multiple partners, but some of them were dependent on female condition. Only initial stages of juvenile growth were influenced by female identity and/or investment.

“Queering Polyamory: Configurations, Public Policy, and Lived Experiences” explores polyamory, a relationship “lovestyle” that involves more then one loving partner, while taking a close look at the social construction of modern day queer polyamory including marriage and sex law. The author states that queer polyamory is socially constructed due to its inclusion of self-identifying gay men, lesbian, bisexual, transgender, transsexual, gender-variant, omnisexual, pansexual, and queer individuals. This thesis includes a study of participants involved in queer polyamorous relationships. The study concludes that a population that engages in queer polyamorous relationships is diverse in regards to demographics; this is to say state of residence, age, gender, ethnicity, religious/spiritual affiliation, sexual identity and/or orientation, and relationship identity and/or orientation and ways individuals come to be part of queer polyamorous relationships. The study looks at how “out” the participants are and how public policy is affecting the lives of those who engage in queer polyamorous relationships. In conclusion, this study suggests future research options and ways society and public policy can begin to alleviate some of the stressors those in queer polyamorous relationships feel due to public policy and morality law. / M.S.