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- W2789270766 abstract "RESUMELe Grand tetras est un galliforme de montagne apparente au faisan et au tetras lyre. Il est distribue de maniere continue a travers la toundra et les montagnes de moyenne altitude en Europe de l'ouest. Toutefois, les populations d'Europe de l'ouest ont subi un declin constant au cours des derniers siecles. Les causes de ce declin sont probablement liees a l'activite humaine, telle .que l'elevage ou le tourisme, qui ont engendre une modification et une fragmentation de l'habitat de l'espece. Malheureusement, les populations soumises a de forts declins demographiques peuvent subir des effets genetiques (augmentation de la consanguinite et perte de diversite genetique) pouvant diminuer leur potentiel de reproduction et conduire irremediablement a l'extinction. Cette these presente les analyses conduites dans le but d'estimer l'impact du declin demographique des populations de Grand tetras sur l'etendue et la distribution de leur variabilite genetique dans le Jura et dans les Pyrenees.Du fait de la legislation locale protegeant les tetraonides en general, mais egalement en raison de la biologie tres cryptique du Grand tetras, l'ensemble des analyses de cette etude a ete realise a partir de materiel genetique extrait des fientes (ou echantillonnage genetique non invasif). Dans la premiere partie de l'etude, je detaille les protocoles d'extraction. d'ADN et d'amplification par PCR modifies a partir des protocoles classiques utilisant des echantillons conventionnels, riches en ADN. L'utilisation d'ADN fecal impose des contraintes dues a la mauvaise qualite et a la faible quantite du materiel genetique a disposition dans les fientes. Ces contraintes ont pu etre partiellement contournees en realisant des repetitions multiples du genotypage afin d'obtenir un degre de fiabilite suffisante. J'ai egalement analyse les causes de la degradation de l'ADN dans les excrements. Parmi les causes les plus communes, telles que l'activite bacterienne, l'hydrolyse spontanee et la degradation enzymatique par les DNases libres, c'est ce dernier facteur qui apparait comme etant la cause majeure et la plus rapide responsable de la degradation de la qualite des echantillons. La rapidite de l'action enzymatique suggere que les plans d'echantillonnages de excrements sur le terrain pourraient etre optimises en les realisant dans des conditions climatiques froides et seches, favorisant ainsi l'inhibition des DNases.La seconde partie de la these est une etude par simulation visant a determiner la capacite du logiciel Structure a identifier les structures genetiques complexes et hierarchiques frequemment rencontrees dans les populations naturelles, et ce en utilisant differents types de marqueurs genetiques.Les troisieme et quatrieme parties de cette these decrivent le statut genetique des populations residuelles du Jura et des Pyrenees a partir de l'analyse de 11 loci microsatellites. Nous n'avons pas pu mettre en evidence dans les deux populations des effets lies a la consanguinite ou a la reduction de la diversite genetique. De plus, la differenciation genetique entre les patches d'habitats favorables reste moderee et correlee a la distance geographique, ce qui suggere que la dispersion d'individus entre les patches a ete importante au moins pendant ces dernieres generations. La comparaison des parametres de la diversite genetique avec ceux d'autres populations de Grand tetras, ou d'autres especes proches, indique que la population du Jura a retenu une proportion importante de sa diversite originelle. Ces resultats suggerent que le declin recent des populations a jusqu'ici eu un impact modere sur les facteurs genetiques et que ces populations semblent avoir conserve le potentiel genetique necessaire a leur survie a long terme.Finalement, en cinquieme partie, l'analyse de l'apparentement entre les mâles qui participent a la parade sur les places de chant (leks) indique que ces derniers sont distribues en agregats de maniere non aleatoire, preferentiellement entre individus apparentes. De plus, la correlation entre les distances genetique et geographique entre les leks est en accord avec les motifs d'isolement par la distance mis en evidence a d'autres niveaux hierarchiques (entre patches d'habitat et populations), ainsi qu'avec les etudes menees sur d'autres especes ayant choisi ce meme systeme de reproduction.En conclusion, cette premiere etude basee uniquement sur de l'ADN nucleaire aviaire extrait a partir de feces a fourni des informations nouvelles qui n'auraient pas pu etre obtenues par une methode d'observation sur le terrain ou d'echantillonnage genetique classique. Aucun oiseau n'a ete derange ou capture, et les resultats sont comparables a d'autres etudes concernant des especes proches. Neanmoins, la taille de ces populations approche des niveaux au-dessous desquels la survie a long terme est fortement incertaine. La persistance de la diversite genetique pour les prochaines generations reste en consequence liee a la survie des adultes et a une reprise du succes de la reproduction.ABSTRACTCapercaillie (Tetrao urogallus) is a large grouse that is continuously distributed across the tundra and the mid-high mountains of Western Europe. However, the populations in Western Europe have been showing a constant decline during the last decades. The causes for this decline are possibly related to human activities, such as cattle breeding and tourism that have both led to habitat modification and fragmentation. Unfortunately, populations that have undergone drastic demographic bottlenecks often go through genetic processes of inbreeding and loss of diversity that decrease their fitness and eventually lead to extinction.This thesis presents the investigations conducted to estimate the impact of the demographic decline of capercaillie populations on the extent and distribution of their genetic variability in the Jura and in the Pyrenees mountains.Because grouse are protected by wildlife legislation, and also because of the cryptic behaviour of capercaillie, all DNA material used in this study was extracted from faeces (non-invasive genetic sampling).In the first part of my thesis, I detail the protocols of DNA extraction and PCR amplification adapted from classical methods using conventional DNA-rich samples. The use of faecal DNA imposes specific constraints due to the low quantity and the highly degraded genetic material available. These constraints are partially overcome by performing multiple genotyping repetitions to obtain sufficient reliability. I also investigate the causes of DNA degradation in faeces. Among the main degraders, namely bacterial activity, spontaneous hydrolysis, and free-¬DNase activities, the latter was pointed out as the most important according to our experiments. These enzymes degrade DNA very rapidly, and, as a consequence, faeces sampling schemes must be planned preferably in cold and dry weather conditions, allowing for enzyme activity inhibition.The second part of the thesis is a simulation study aiming to assess the capacity of the software Structure to detect population structure in hierarchical models relevant to situations encountered in wild populations, using several genetic markers. The methods implemented in Structure appear efficient in detecting the highest hierarchical structure. The third and fourth parts of the thesis describe the population genetics status of the remaining Jura and Pyrenees populations using 11 microsatellite loci. In either of these populations, no inbreeding nor reduced genetic diversity was detected. Furthermore, the genetic differentiation between patches defined by habitat suitability remains moderate and correlated with geographical distance, suggesting that significant dispersion between patches was at work at least until the last generations. The comparison of diversity indicators with other species or other populations of capercaillie indicate that population in the Jura has retained a large part of its original genetic diversity. These results suggest that the recent decline has had so forth a moderate impact on genetic factors and that these populations might have retained the potential for long term survival, if the decline is stopped.Finally, in the fifth part, the analysis of relatedness between males participating in the reproduction parade, or lek, indicate that capercaillie males, like has been shown for some other grouse species, gather on leks among individuals that are more related than the average of the population. This pattern appears to be due to both population structure and kin-association.As a conclusion, this first study relying exclusively on nuclear DNA extracted from faeces has provided novel information that was not available through field observation or classical genetic sampling. No bird has been captured or disturbed, and the results are consistent with other studies of closely related species. However, the size of these populations is approaching thresholds below which long-term survival is unlikely. The persistence of genetic diversity for the forthcoming generations remains therefore bond to adult survival and to the increase of reproduction success." @default.
- W2789270766 created "2018-03-29" @default.
- W2789270766 creator A5049599323 @default.
- W2789270766 date "2004-01-01" @default.
- W2789270766 modified "2023-09-27" @default.
- W2789270766 title "Population genetics of Capercaillie (Tetrao urogallus) in the Jura and the Pyrenees: a non-invasive approach to avian conservation genetics" @default.
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