Hybridization and genetic introgression are significant evolutionary processes playing a keyrole in the adaptation and diversification of species. In desert ants of the genus Cataglyphis,some species have evolved a remarkable reproductive strategy, termed social hybridogenesis,that relies on a perpetual hybridization between two sympatric, yet genetically distinct lineages.The non-reproductive workers systematically result from mating between partners of differentlineages; in contrast, queens and males are both produced asexually by parthenogenesis.Consequently, workers are all interlineage hybrids, whereas reproductives are all pure-lineageindividuals. Although several studies have been carried out on the reproductive strategies ofCataglyphis desert ants, the origin and the mechanisms underlying social hybridogenesis in thegenus remain unclear.In this thesis, I first examined three aspects associated to the persistence of socialhybridogenesis using the ant Cataglyphis mauritanica as a model. (i) I showed that the tightcaste – genotype association stems from a strong genetic influence on female caste fate.However, some degree of phenotypic plasticity was retained in hybrid as well as pure-lineagegenomes, although not expressed in natural conditions. (ii) The genetic survey of a largehybridogenetic population of C. mauritanica reveals that the two lineages occur with equalfrequency. Furthermore, restricted dispersal and parthenogenetic production of queens result ina mosaic of clonal patches. In contrast, males disperse over patches, ensuring successfulinterlineage mating. (iii) To determine whether mating between partners from the same geneticlineage participate to queen production, I simulated genetic data under various rates of sexualvs. asexual queen production. I found that genetic diversity within each lineage fits with theoccurrence a few sex; however, the 100% clonality hypothesis could not be discarded.I then investigated the evolutionary origin of social hybridogenesis in Cataglyphis. Bycharacterizing the reproductive system of 11 Cataglyphis species, five new instances of socialhybridogenesis were discovered. Inferences from phylogenetic analyses, including thesespecies and all Cataglyphis species for which reproductive information was available, indicatedthat this reproductive system independently evolved multiple times in the genus Cataglyphis.Overall, the results of this thesis highlight the singularities of a hybridogenesic systemassociated to queen parthenogenesis, which may have facilitated the repeated evolution ofdependent-lineages in Cataglyphis ants. / L’hybridation et l’introgression génétique jouent un rôle majeur dans l’adaptation et ladiversification des espèces. Chez les fourmis du désert du genre Cataglyphis, certaines espècesont évolué une stratégie de reproduction remarquable, appelée hybridogenèse sociale, reposantsur l’hybridation systématique entre deux lignées génétiquement distinctes. Les ouvrières nonreproductricessont issues de l’accouplement entre des partenaires de lignées distinctes ;enrevanche, les reines et les mâles sont produits de façon asexuée par parthénogenèse. Lesouvrières sont donc toutes des hybrides des deux lignées, alors que les individus reproducteurssont de pure-lignées. Bien que plusieurs études aient analysé les stratégies de reproduction desfourmis Cataglyphis, l’origine et le fonctionnement de l’hybridogenèse sociale au sein du genrerestent obscurs.Dans cette thèse, trois aspects associés au maintien de ce système ont premièrement étéétudiés en prenant la fourmi Cataglyphis mauritanica comme modèle. (i) La forte associationentre génotype et caste des femelles est lié à une forte influence génétique sur le déterminismede la caste. Néanmoins, une certaine plasticité phénotypique est maintenue dans les génomeshybrides et pure-lignée mais elle ne s’exprime pas en conditions naturelles. (ii) L’analysegénétique d’une population hybridogène de C. mauritanica montre que les deux lignées sontéquifréquentes. De plus, une dispersion limitée des reines ainsi que leur production parparthénogenèse mènent à la formation d’une mosaïque de patches clonaux. A l’inverse, lesmâles dispersent d’un patch à l’autre assurant les accouplements interlignées. (iii) Afin dedéterminer si les accouplements intralignées participent à la production des reines, des donnéesgénétiques ont été simulées sous différents taux de reproduction sexuée et asexuée. Les résultatsmontrent que la diversité génétique au sein de chaque lignée correspond à une faible fréquencede reproduction sexuée, bien que qu’un scénario avec 100% de clonalité ne puisse être écarté.Ensuite, l’origine évolutive de l’hybridogenèse sociale chez les Cataglyphis a étéanalysée. L’étude des systèmes reproducteurs de 11 espèces de Cataglyphis a permis ladécouverte de 5 nouveaux systèmes hybridogènes. Des analyses phylogénétiques, basées surces espèces et sur toutes les espèces de Cataglyphis pour lesquels le système reproducteur a étéprécédemment étudié, indiquent que ce système reproducteur aurait évolué plusieurs foisindépendamment au sein du genre Cataglyphis.En conclusion, les résultats de cette thèse soulignent les singularités d’un systèmehybridogène associé à la parthénogénèse des reines, qui a pu faciliter l’évolution répétée delignées dépendantes chez les fourmis Cataglyphis. / Doctorat en Sciences / info:eu-repo/semantics/nonPublished

Sex and meiosis are ubiquitous in eukaryotes as the primary mode of reproduction. This suggests that despite the theoretical energetic advantages of asexual reproduction, organisms capable of sexual reproduction are at a much greater long-term evolutionary advantage. Rotifers, a group of microinvertebrates, offer unique opportunities to examine the evolution of sex due to their extensive proliferation, successful adaptation to a wide variety of ecological niches, and the diversity of reproductive modes represented in the group. The cyclically parthenogenetic monogonont rotifers have overcome constraints on the loss of sexual reproduction in order to frequently transition between sexual and asexual generations, making them a powerful system with which to address the maintenance of sex in animals. Obligately asexual bdelloid rotifers appear to have thrived without sex for tens of millions of years, a period of time much longer than expected given the hypothesized advantages of sexual reproduction. However, the molecular nature of sex and parthenogenesis is poorly understood in any rotifer species. To expand our knowledge of the molecular mechanisms of monogonont reproduction, we sequenced genomes of two distantly related species, Brachionus calyciflorus and Brachionus manjavacas and identified over 80 homologs for genes involved in meiotic processes. Several of these genes have undergone duplication events specific to the monogonont lineage, including genes with known roles in regulation of cell cycle transitions during meiosis. In addition, global gene expression patterns were determined using obligate parthenogenetic (OP) and cyclical parthenogenetic (CP) strains of B. calyciflorus. Quantitative comparison of expression between these strains revealed differentially expressed genes specific to sexual and asexual reproduction in this species, including genes related to dormancy/resting egg formation, meiosis, and hormone signaling pathways that are thought to be involved in the induction of sexual reproduction in monogononts. Finally, we analyzed gene expression in bdelloid rotifers for evidence of sexual reproduction or the utilization of meiotic genes under conditions inducing high levels of recombination. Through this work, we have established molecular markers for sexuality and asexuality in monogonont rotifers, and used these markers to evaluate reproduction in bdelloids. The data generated specifically allows for more informed analyses of the evolution of cyclical parthenogenesis and rotifer reproduction. Furthermore, this work extends the use of monogononts as a model system for addressing broader questions regarding the evolution of sexual reproduction.

<p>Asexual reproduction and polyploidy are relatively rare in animals with chromosomal sex determination and always represent a derived condition. To accomplish asexual reproduction several changes in gene expression are required in the mechanism of oogenesis. Polyploidy increases the cell volume and also gives rise to alterations in general physiology. Nevertheless, there are asexual animals that not only survive but seem to be doing better than their sexual progenitors. This is expressed in the distribution pattern called geographical parthenogenesis. Using molecular phylogeny, I here examine the evolution of Otiorynchid weevils, mainly <i>Otiorhynchus scaber</i> and <i>sulcatus</i> in an attempt to trace the evolutionary history and find out what causes the variation in success of different parthenogens. I also evaluate the contribution of asexuality, hybridity and polyploidy as explanations behind geographical parthenogenesis in insects. I conclude that what is called <i>O. scaber</i> is, in fact, a set of geographical polyploids as polyploidy and not asexuality explains the difference in clonal success. I also argue that <i>O. sulcatus</i> is a recently formed clonal species of non-hybrid origin that may well be a good example of a true general purpose genotype. I find little support for asexuality or a hybrid origin as explanations behind geographical parthenogenesis in insects. Finally, I argue that polyploidy in all eukaryotes should be seen as an opportunity for the species evolution, not as a limitation that ensures the demise of the taxa.</p>

Asexual reproduction and polyploidy are relatively rare in animals with chromosomal sex determination and always represent a derived condition. To accomplish asexual reproduction several changes in gene expression are required in the mechanism of oogenesis. Polyploidy increases the cell volume and also gives rise to alterations in general physiology. Nevertheless, there are asexual animals that not only survive but seem to be doing better than their sexual progenitors. This is expressed in the distribution pattern called geographical parthenogenesis. Using molecular phylogeny, I here examine the evolution of Otiorynchid weevils, mainly Otiorhynchus scaber and sulcatus in an attempt to trace the evolutionary history and find out what causes the variation in success of different parthenogens. I also evaluate the contribution of asexuality, hybridity and polyploidy as explanations behind geographical parthenogenesis in insects. I conclude that what is called O. scaber is, in fact, a set of geographical polyploids as polyploidy and not asexuality explains the difference in clonal success. I also argue that O. sulcatus is a recently formed clonal species of non-hybrid origin that may well be a good example of a true general purpose genotype. I find little support for asexuality or a hybrid origin as explanations behind geographical parthenogenesis in insects. Finally, I argue that polyploidy in all eukaryotes should be seen as an opportunity for the species evolution, not as a limitation that ensures the demise of the taxa.

Apomixis, or asexual seed development, if introduced into crop species, has the potential to greatly improve global food production. Towards this goal, this study focused on uncovering the genetic mechanisms that control the parthenogenesis step within apomixis whereby fertilisation is avoided. In the model apomict, Hieracium praealtum (Asteraceae), parthenogenesis is controlled by the LOSS OF PARTHENOGENESIS (LOP) locus. Previous research showed that in addition to genomic copies of candidate genes at LOP, the genome has at least three other copies referred to as alternative alleles. The main goal of this study was to investigate four candidate genes, Genes B, X, H and Y, at LOP by generating segregation data of the alternative alleles. BAC clones containing alternative allele sequences were identified and Roche 454 pyrosequenced. These sequences were used to design alternative allele specific primers for genotyping two Hieracium praealtum polyhaploid populations (~ 300 plants). Four major conclusions were drawn from this study. First, the alternative alleles were in fact acting like alleles to the LOP alleles of Genes B, X and Y. Second, allelic sequence divergence (ASD) of the LOP alleles of Genes B and X relative to the alternative alleles, indicated a recent and separate evolutionary history. Third and, unexpectedly, recombination was detected at the LOP locus, in contrast to other apomixis loci reported in the literature. Furthermore, Gene B was found to be very closely associated with parthenogenesis in the polyhaploid population indicating that it may be essential to parthenogenesis and therefore requires further investigation. On the other hand, the absence of Genes X, Y and H, due to recombination, had no impact upon parthenogenesis. Fourth, the sequence data suggested that the LOP and alternative alleles originated from a shared common allele ancestor. It is hoped that these findings have made a significant contribution towards the future goal of introducing apomixis into crop species.

No description available.

Tendo em vista a possibilidade da associação de agentes ativadores aliada à influência da idade do oócito no desenvolvimento embrionário, a proposta deste trabalho foi estudar a relação entre o envelhecimento do oócito e a ativação partenogenética. Para tal, oócitos bovinos foram maturados in vitro por um período de 22 h (jovens) e 28 h (envelhecidos). Em seguida, os dois grupos de oócitos foram ativados com os tratamentos: ID3: ionomicina (5 µM por 5 min) + 6DMAP (2 mM por 3 h de incubação); ID6: ionomicina (5 µM por 5 min) + 6DMAP (2 mM por 6 h de incubação); IDS: ionomicina + associação 6DMAP (2 mM) e estrôncio (20 mM; SrCl2) por 6 h e IDSS: ionomicina + (6DMAP+Sr) nas primeiras 3 h, seguido de lavagem e incubação com estrôncio (Sr2+) isoladamente por mais 3 h de incubação. O grupo controle foi cultivado na ausência de qualquer agente ativador (ativação espontânea). Após a ativação os oócitos foram avaliados quanto a: 1) taxa de ativação (formação de pronúcleo às 12 hpa); 2) atividade do fator promotor de maturação (MPF) e proteína cinase ativada por mitógeno (MAPK) nos intervalos de 5 min, 3 h, 6 h e 10 h; 3) desenvolvimento embrionário (taxa de clivagem às 48 h, dia 7 e 9 taxas de blastocisto e eclosão); 4) qualidade dos embriões (dia 9 pelo número total de células, apoptose e expressão de interferon-t). Em geral, oócitos jovens apresentaram menor taxa de ativação e maior atividade de MPF e MAPK em relação aos envelhecidos. No entanto, a incubação dos oócitos em 6DMAP por 6 h permitiu taxas semelhantes aos envelhecidos com pequeno prejuízo em número de células, sem efeitos em outros critérios de qualidade do embrião. Os dados sugerem possíveis aplicações destes resultados de maneira a contribuir para a TN com flexibilidade de horários e produção de embriões de boa qualidade. / Considering the possibility of the combination of different activating agents associated to the influence of oocyte ageing on embryo development, the purpose of this work to study the relationship between oocyte ageing and parthenogenetic activation. Bovine oocytes were in vitro maturated for 22 (young) and 28 h (aged). Next, both groups of oocytes were activated using the following treatments: ID3: ionomycin (5 µM for 5 min) + 6DMAP (2 mM for 3 h); ID6: ionomycin (5 µM for 5 min) + 6DMAP (2 mM for 6 h); IDS: ionomicyn + 6DMAP (2 mM) and strontium (20 mM; SrCl2) for 6 h and IDSS: ionomicyn + (6DMAP+Sr2+) for the first 3h, followed by incubation with Sr2+ alone for another 3 h. The control group was cultured in the absence of any activating agents (spontaneous activation). After activation, the oocytes were evaluated for: 1) activation rate (pronuclei formation at 12 hpa); 2) activity of maturation promoting factor (MPF) and mitogen activated protein kinase (MAPK) at 5 min, 3 h, 6 h and 10 hpa; 3) embryo development (cleavage rate at 48 h and blastocyst and hatching rates on days 7 and 9); 4) embryo quality (day 9 regarding total cell numbers, apoptosis and interferon-t expression). In general, young oocytes showed lower activation rates and higher MPF and MAPK activity when compared with aged oocytes. However, incubation of the oocytes with 6DMAP for 6 h allowed development rates similar to aged oocytes with a small decrease in total cell number, but without effects on other criteria of embryo quality. The data suggest a possible application of these results in such a way to contribute for timing flexibilization in NT experiments and production of good quality embryos.

As taxas de produção embrionária tanto da FIV (30-40%) como da TN (23%) ainda estão aquém do esperado. Desta forma, a pré-maturação com inibidores do ciclo celular é uma das alternativas que vem sendo estudada para aumentar a competência dos oócitos utilizados na PIV, na tentativa de otimizar o sucesso das biotécnicas. Sabe-se que neurotrofinas desempenham funções no sistema reprodutor. O BDNF é um exemplo de neurotrofina que parece estar relacionada com a maturação dos oócitos. Desta forma, o objetivo deste trabalho foi de aperfeiçoar a pré-maturação e a maturação in vitro de oócitos bovinos submetidos posteriormente à ativação partenogenética, visando seu uso na biotécnica de transferência de núcleo. Oócitos bovinos foram submetidos à maturação na presença (MIV/BD) ou ausência (MIV) de BDNF ou pré-maturados com BLI e suplementados (BL/BD) ou não (BL) com a neurotrofina. Posteriormente foram avaliados quanto à taxa de maturação (metáfase II), ativação (formação de prónúcleo) e desenvolvimento embrionário (produção e qualidade dos blastocistos). Não houve diferença (P>0,05) entre taxas de MII após a maturação com ou sem BDNF. Porém, o grupo pré-maturado e suplementado (BL/BD n=73; 91,2%) apresentou maior taxa de MII (P<0,05) em relação ao grupo não suplementado (BL n=66; 76,7%). Oócitos maturados nas mesmas condições foram ativados quimicamente para análise do desenvolvimento embrionário. Os grupos MIV/BD (n=30; 71,4%) e MIV (n=41; 91.1%) apresentaram diferença (P<0,05) em relação à taxa de ativação. Porém, não foi observada diferença quanto aos outros parâmetros do desenvolvimento. Quando os oócitos foram pré-maturados a taxa de clivagem do grupo suplementado (BL/BD: n=227; 65,2%) foi superior (P<0,05) ao grupo não suplementado (BL: n=187; 57,7%), mas não foram observadas diferenças (P>0,05) para os outros parâmetros de desenvolvimento. A qualidade dos embriões ativados também não foi afetada pelos tratamentos. Os grupos submetidos à TN (MIV e BL/BD) apresentaram diferenças (P<0,05) para extrusão do 1°CP (n=639; 63,5% e n=693; 69,5%, respectivamente) e para taxa de fusão (n=345; 72,9% e n=397; 79,2%, respectivamente) não havendo diferença para nenhum outro parâmetro avaliado. A qualidade dos embriões clonados também foi avaliada e não foi observada diferença. Após a transferência dos embriões dos grupos MIV (n=28) e BL/BD (n=26) para as receptoras, os grupos foram capazes de produzir gestação avançadas (10,7 e 11,5%, respectivamente) de forma similar (P>0,05). Com base nestes resultados podemos concluir que a suplementação, tanto da maturação como a pré-maturação não causa prejuízo no posterior desenvolvimento embrionário. Ainda, embriões clonados produzidos a partir de oócitos bloqueados são capazes de estabelecer gestações avançadas em bovinos. / Embryo production rates obtained from both IVF (30-40%) and NT (23%) are still below the expected values. Therefore, oocyte pre-maturation using cell cycle inhibitors is one of the alternatives which has been studied to increase the competence of oocytes used for IVP, as an attempt to optimize the success rates of these biotechniques. Neurotrophins are known to play several roles in the reproductive system. BDNF is an example of a neurotrophin that seems to be related to oocyte maturation. Therefore, the objective of this study was to improve techniques of pre-maturation and maturation of bovine oocytes submitted to parthenogenetic activation, aiming for its use on cloning by nuclear transfer. Bovine oocytes were submitted to maturation either in presence (IVM/BD) or absence (IVM) of BDNF or pre-matured with BLI and supplemented (BL/BD) or not (BL) with the neurotrophin. Groups were evaluated for maturation rates (metaphase II), activation (pro-nucleus formation) and embryo development (blastocyst formation rate and quality). There was no difference (P>0.05) in MII rate after the maturation with or without BDNF. However, pre-maturation in the supplemented group (BL/BD, n=73; 91.2%) resulted in higher MII rate (P<0.05) when compared with the nonsupplemented group (BL, n=66; 76.7%). Oocytes which were matured under the same conditions were also activated chemically for embryonic development analysis. Activation rates were different (P<0.05) from IVM/BD groups (n=30; 71.4%) and IVM (n=41; 91.1%). However, no difference were observed for development parameters. When the oocytes were prematured, cleavage rates in the supplemented group were superior (P<0.05) than non supplemented group (BL/BD: n=227; 65.2%) and (BL: n=187; 57.7%), but no difference was observed for other developmental parameters. Embryo quality was also evaluated and no difference was observed between treatments. Groups submitted to NT (IVM and BL/BD) differed regarding (P<0.05) the 1stPB extrusion (n=639; 63.5% and n=693; 69.5%, respectively) and fusion rate (n=345; 72.9% and n=397; 79.2%, respectively), but did not present differences for other evaluated parameters. Embryo quality was evaluated again and no differences were observed. After the embryos were transferred to recipient cows, groups IVM (n=3; 10.7%) and BL/BD (n=3; 11.5%) were capable of producing advanced gestations at similar rates (P>0.05). Based on these results, it may be concluded that supplementation of both maturation and pre-maturation does not impair embryonic development. Additionally, cloned embryos produced from blocked oocytes are able to establish advanced gestation in cattle.

No description available.

No description available.