<p>Dans ce travail, les préférences alimentaires pour les espèces végétales consommées par les lombriciens peuplant certains îlots des pelouses de l’avenue Roosevelt ont été étudiées. L’analyse des contenus digestifs et des fèces des vers a montré que les plantes identifiées dans les pelouses ne sont pas toutes consommées.<br> Mesurée par l’indice d’Ivlev, la sélectivité des items végétaux est variable en fonction de l’espèce de ver, de la classe d’âge et de la saison. Lorsque les dicotylédones sont en plein développement au printemps et en été, les choix des vers sont surtout manifestés pour les monocotylédones. En automne et en hiver, les monocotylédones prédominent et, les dicotylédones se retrouvant dans la litière, font l’objet de préférences marquées qui induisent des rejets relatifs de monocotylédones. Bien que Lolium perenne soit la plante la plus consommée, Bellis perennis est la dicotylédone la plus appréciée, Trifolium repens et Poa trivialis étant les plantes généralement rejetées.<br> L’indice d’Ivlev n’ayant permis de connaître que les rangs de préférences des différentes espèces végétales, les analyses ont été complétées par des tests du χ² qui ont montré que la consommation des plantes par les vers ne se fait pas au hasard. <p>Les épigés Satchellius mammalis et Lumbricus rubellus sont les espèces qui présentent le taux le plus élevé de matière organique figurée (respectivement 27 % et 26 % [19 % chez les jeunes Lumbricus spp]) dans leurs contenus digestifs. Chez les anéciques Aporrectodea longa et Lumbricus terrestris, ces taux sont très faibles (respectivement 6 % [2 fois plus chez les jeunes vers] et 11 %). Les endogés (Aporrectodea caliginosa, A. icterica et A. rosea) présentent des taux variant respectivement de 21 % [9 % chez les jeunes vers] à 8 % et 11 %. <p>L’axe de la taille des particules consommées n’a pas permis une ségrégation des niches (d’après notre étude, la taille des vers n’affecte pas celle des particules ingérées), mais l’axe de la nature des particules consommées est plus discriminant. Dans la niche tridimensionnelle (taille et nature des particules ingérées, notre étude, et les cycles annuels d’activité [Tiho, 2001]), le seul recouvrement fort qui se maintienne est celui de la niche de L. rubellus sur celle de L. terrestris. Un recouvrement marginal (α = 0,66) est observé, celui de la niche de A. longa sur celle de L. terrestris. Ceci révèle une compétition interspécifique entre ces trois espèces ayant des régimes alimentaires très proches. <p> <p>In this study, preferences for plants consumed by earthworms inhabiting certain islets of the Roosevelt avenue lawns have been studied. Examination of gut contents and faeces showed that not all of the plants identified in the lawns are consumed.<br> Measured by the Ivlev’s electivity index, the selectivity of plants is variable according to the earthworm species, its size class and the season. When the dicotyledons are developing in spring and in summer, the choices of the earthworms are particularly observed for the monocotyledons. In autumn and winter, the monocotyledons are developing and the dicotyledons in the litter are highly chosen, leading the relative reject of the monocotyledons.<br> Although Lolium perenne is the most consumed plant, Bellis perennis is the most appreciated dicotyledon, Trifolium repens and Poa trivialis being generally rejected.<br> As the Ivlev’s index of preference has only permit to know the rank of preference of the different plants, the analysis was completed by the χ² tests which demonstrated that the consumption of plants by earthworms is not done randomly. <p>The epigées Satchellius mammalis and Lumbricus rubellus are the species which present the highest rate of organic matter (respectively 27 % and 26 % [19 % for the immatures Lumbricus spp] in their gut contents.<br> For the anéciques Aporrectodea longa and Lumbricus terrestris, these rates are very low (respectively 6 % [twice more for the immatures worms] and 11 %).<br> The endogées (Aporrectodea caliginosa, Aporrectodea icterica and Aporrectodea rosea) present rates varying respectively from 21 % [9 % for the young worms] to 8 % and 11 %. <p>The axis of the particles size ingested did not permit the niches segregation (in our study, the earthworms size does not affect the size of the particles ingested), but the axis of the nature of the particles ingested is more discriminant. In the three-dimensional niche (size and nature of particles ingested [our study] and the annuals cycles of activity [Tiho, 2001]), the young worms not being considered, only one high overlap is maintained, that of L. rubellus niche on that of L. terrestris. A marginal overlap (α = 0.66) is observed, that of A. longa niche on that of L. terrestris. Having a similar trophic resource (consumption of litter), an interspecific competition must exist between these three species for the access to the food.

Orientador: Marco Antonio de Assis / Resumo: Epífitas são plantas que, em algum estágio do ciclo de vida, sobrevivem sem estar conectadas ao solo. Estão presentes em todos os grandes grupos de traqueófitas e abrangem cerca de 10% de suas espécies. Diversos estudos têm sido feitos com o intuito de se conhecer a flora epifítica dos remanescentes florestais brasileiros, porém, apesar dos esforços dos pesquisadores, ainda há muito trabalho a ser feito, sendo a pesquisa taxonômica um instrumento importante para se compreender a biodiversidade. O presente trabalho foi desenvolvido no Parque Estadual do Morro do Diabo, uma área de Floresta Estacional Semidecidual localizada no extremo oeste do estado de São Paulo. Desse modo, pretendeu-se contribuir para o conhecimento da biodiversidade da região, realizando um inventário florístico das epífitas vasculares, com a elaboração de chaves de identificação dicotômicas e de um guia ilustrado das epífitas vasculares do Parque. As epífitas vasculares amostradas foram classificadas de acordo com categorias ecológicas e síndromes de dispersão. Foram coletadas 75 espécies de epífitas vasculares, distribuídas em 49 gêneros e 11 famílias. Orchidaceae, Bromeliaceae e Polypodiaceae foram as famílias mais representativas, totalizando 68% das espécies amostradas. Peperomia e Tillandsia foram os gêneros mais ricos. A categoria ecológica das holoepífitas características compreendeu 85% das espécies e a anemocoria foi a síndrome de dispersão predominante, ocorrendo em 76% das espécies. A análise d... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Epiphytes are plants that at some stage in their life cycle survive without being connected to the soil. They are present in all major groups of tracheophytes and comprise about 10% of their species. Several studies have been done with the purpose of knowing the epiphytic flora of brazilian forest remnants, but despite the efforts of the researchers, there is still much work to be done, and taxonomic research is an important tool to understand biodiversity. The present work was developed in the Parque Estadual do Morro do Diabo, an area of semideciduous seasonal forest located in the extreme west of São Paulo state. The aimed of this present study was contribute to the knowledge of the region's biodiversity, by making a floristic inventory of the vascular epiphytes with the elaboration of dichotomous identification keys and an illustrated guide of the vascular epiphytes of the Parque. The vascular epiphytes sampled were classified according to ecological categories and dispersion syndromes. Seventy five species of vascular epiphytes were collected, corresponding 49 genera and 11 families. Orchidaceae, Bromeliaceae and Polypodiaceae were the most representative families, totalizing 68% of the sampled species. Peperomia and Tillandsia were the richest genera. The ecological category of the characteristic holoepiphytes comprised 85% and anemochory was the predominant dispersion syndrome, corresponding 76% of the species. The analysis of floristic similarity indicated an area in ... (Complete abstract click electronic access below) / Mestre

\ / Doctorat en sciences, Spécialisation biologie animale / info:eu-repo/semantics/nonPublished