Dynamique des introgressions réciproques de la faune des scarabéides coprophages entre la zone méditerranéenne et la chaîne alpine : implications biogéographiques
Institution:
Montpellier 3Disciplines:
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Abstract EN:
The thesis was divided into two parts, each corresponding to a scale of analysis of the distribution of dung beetles. Firstly, the distribution of dung beetles in france was analysed considering successively the aphodiinae, geotrupinae and scarabaeidae groups. The geographical informations were extracted from the database of the atlas des scarabeides laparosticti de france (lumaret, 1990). Whereas aphodiinae and geotrupinae showed their good adaptation to the whole french climatic conditions, most of scarabaeidae species were quartered at the mediterranean area. The study of the corsican fauna highlighted the influence of the interspecific competition on the species distribution. In the second part, the author specifically studied an altitudinal gradient along the verdon valley, which was located on the borders of the alps and the mediterranean area. In this valley, the distribution of aphodiinae, geotrupinae, coprinae and scarabaeidae was successively analysed in five sites which were representative of the regional conditions. Interestingly, the distributional patterns of dung beetles at the regional scale was very similar to what was observed at the geographical scale of france. Coprinae took advantage of the mediterranean climatic conditions to be highly represented in the communities of high altitude, but the species have been affected by the recent forest expansion. Conversely, aphodiinae and geotrupinae were more ubiquitous, and several species were favoured by the forest environment. Along the altitudinal gradient, the communities did not constitute a gradual continuum, but the communities were as mosaic, each of them reflecting microenvironmental conditions.
Abstract FR:
Dans une premiere partie, on a analyse la repartition francaise des scarabaeoidea coprophages grace aux informations contenues dans la base de donnees de l'atlas des scarabeides laparosticti de france (lumaret, 1990) en considerant successivement les aphodiinae, les geotrupinae et les scarabaeidae. Tandis que les aphodiinae et les geotrupinae montrent une bonne adaptation aux conditions climatiques regnant en france, la plupart des scarabaeidae sont cantonnes dans la region mediterraneenne. Parallelement, l'etude de la faune corse souligne l'influence de la competition sur la distribution des especes, en particulier en region mediterraneenne. Dans une seconde partie, on s'est interesse specifiquement a une vallee situee entre la region mediterraneenne et les alpes (haute vallee du verdon). Dans ce secteur, on a etudie la repartition des aphodiinae, des geotrupinae, des coprinae et des scarabaeinae a partir de cinq sites representatifs des conditions environnementales locales. Il est interessant de remarquer que l'on retrouve dans la vallee les memes caracteristiques que celles mises en evidence pour la france. Ainsi, a la faveur des influences mediterraneennes les coprinae, qui sont surtout des especes de plaine, constituent des communautes importantes jusqu'en haute altitude. Parallelement, ces insectes sont tres sensibles a la fermeture du milieu. De leur cote, les aphodiinae et les geotrupinae font preuve d'une plus grande valence ecologique, certaines especes recherchant meme les milieux forestiers. Le long du gradient altitudinal, la repartition des especes ne forme donc pas un continuum, mais plutot une mosaique de communautes dont les caracteristiques sont le reflet de la mosaique environnementale.