The mechanisms responsible for species replacement during ecological successions is a long-standing and open debate. In this study, we examined the distribution of the Sardinian warbler Sylvia melanocephala along two ...The mechanisms responsible for species replacement during ecological successions is a long-standing and open debate. In this study, we examined the distribution of the Sardinian warbler Sylvia melanocephala along two grassland-to-forest gradients, one in a high-diversity area （Albera-Aspres chain in Catalonia： eight Sylvia warbler species） and one in a low-diversity area （Mount Hymittos in Greece： four species）. In Catalonia, distribution models suggested that the apparent exclusion of S. melanocephala from the open and forest ends of the gradient may be explained entirely by the preference of S. melanocephala for mid-successional shrublands. However, a joint analysis of both data sets revealed that： 1） S. melanocephala was more evenly dis- tributed along the vegetation gradient in Greece, suggesting ecological release in the low-diversity area; and 2） a distribution model assuming interspecific competition （based on the distribution of Sylvia species showing a negative co-occurrence pattern with S. melanocephala） had a significantly higher predictive ability than a distribution model based on habitat variables alone. Our study supports the view that species turnover along ecological gradients generally results from a combination of intrinsic preferences and interspecific competition [Current Zoology 57 （3）： 307-317, 2011].展开更多
We consider a model of the exploitative competition of two micro-organisms for two complementary nutrients in a chemostat and take into account the interspecific interac- tion. The growth functions occurring in the mo...We consider a model of the exploitative competition of two micro-organisms for two complementary nutrients in a chemostat and take into account the interspecific interac- tion. The growth functions occurring in the model are of general type and the interaction functions are monotonic and positive. By the mean of the Thieme-Zhao theorem, we establish conditions for uniform persistence of the model.展开更多
文摘The mechanisms responsible for species replacement during ecological successions is a long-standing and open debate. In this study, we examined the distribution of the Sardinian warbler Sylvia melanocephala along two grassland-to-forest gradients, one in a high-diversity area （Albera-Aspres chain in Catalonia： eight Sylvia warbler species） and one in a low-diversity area （Mount Hymittos in Greece： four species）. In Catalonia, distribution models suggested that the apparent exclusion of S. melanocephala from the open and forest ends of the gradient may be explained entirely by the preference of S. melanocephala for mid-successional shrublands. However, a joint analysis of both data sets revealed that： 1） S. melanocephala was more evenly dis- tributed along the vegetation gradient in Greece, suggesting ecological release in the low-diversity area; and 2） a distribution model assuming interspecific competition （based on the distribution of Sylvia species showing a negative co-occurrence pattern with S. melanocephala） had a significantly higher predictive ability than a distribution model based on habitat variables alone. Our study supports the view that species turnover along ecological gradients generally results from a combination of intrinsic preferences and interspecific competition [Current Zoology 57 （3）： 307-317, 2011].
文摘We consider a model of the exploitative competition of two micro-organisms for two complementary nutrients in a chemostat and take into account the interspecific interac- tion. The growth functions occurring in the model are of general type and the interaction functions are monotonic and positive. By the mean of the Thieme-Zhao theorem, we establish conditions for uniform persistence of the model.
