2015-05-202015-03-06SILVA, L. A. Campos vetoriais suaves por partes: modelos predador-presa. 2015. 92 f. Dissertação (Mestrado em Matemática) - Universidade Federal de Goiás, Goiânia, 2015.http://repositorio.bc.ufg.br/tede/handle/tede/4559In this work we study the global qualitative behavior of three predator-prey models. We analyze the existence of limit cycle and canard cycle and we investigate the kinds of bifurcation that can occur. In the first model, Gause predator-prey with a refuge, we analyze the effects of a prey refuge on the ecosystem qualitative behavior. Employing the carrying capacity of the prey population in the Gause Model with a refuge we obtain the second model, for which we analyze the effects of the carrying capacity and we compare the results. In the third model we consider the continuous threshold harvesting strategies ocurring when the predator density is above a certain threshold. We note that the model has a complex dynamics with multiple internal equilibria and different types of bifurcation.application/pdfAcesso AbertoModelo predador-presaModelo de Gause com refúgioCiclo limiteCiclo de canardBifurcação Bogdanov-TakensPredator-prey modelGause model with refugeLimit cycleCanard cycleBogdanov-Takens bifurcationCIENCIAS EXATAS E DA TERRA::MATEMATICADissertação