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Differential Success (differential + success)
Selected AbstractsTolerance to herbivory, and not resistance, may explain differential success of invasive, naturalized, and native North American temperate vinesDIVERSITY AND DISTRIBUTIONS, Issue 2 2008Isabel W. Ashton ABSTRACT Numerous hypotheses suggest that natural enemies can influence the dynamics of biological invasions. Here, we use a group of 12 related native, invasive, and naturalized vines to test the relative importance of resistance and tolerance to herbivory in promoting biological invasions. In a field experiment in Long Island, New York, we excluded mammal and insect herbivores and examined plant growth and foliar damage over two growing seasons. This novel approach allowed us to compare the relative damage from mammal and insect herbivores and whether damage rates were related to invasion. In a greenhouse experiment, we simulated herbivory through clipping and measured growth response. After two seasons of excluding herbivores, there was no difference in relative growth rates among invasive, naturalized, and native woody vines, and all vines were susceptible to damage from mammal and insect herbivores. Thus, differential attack by herbivores and plant resistance to herbivory did not explain invasion success of these species. In the field, where damage rates were high, none of the vines were able to fully compensate for damage from mammals. However, in the greenhouse, we found that invasive vines were more tolerant of simulated herbivory than native and naturalized relatives. Our results indicate that invasive vines are not escaping herbivory in the novel range, rather they are persisting despite high rates of herbivore damage in the field. While most studies of invasive plants and natural enemies have focused on resistance, this work suggests that tolerance may also play a large role in facilitating invasions. [source] Breaking taboos in the tropics: incest promotes colonization by wood-boring beetlesGLOBAL ECOLOGY, Issue 4 2001Bjarte H. Jordal Abstract 1,Inbreeding and parthenogenesis are especially frequent in colonizing species of plants and animals, and inbreeding in wood-boring species in the weevil families Scolytinae and Platypodidae is especially common on small islands. In order to study the relationship between colonization success, island attributes and mating system in these beetles, we analysed the relative proportions of inbreeders and outbreeders for 45 Pacific and Old World tropical islands plus two adjacent mainland sites, and scored islands for size, distance from nearest source population, and maximum altitude. 2,The numbers of wood-borer species decreased with decreasing island size, as expected; the degree of isolation and maximum island altitude had negligible effects on total species numbers. 3,Numbers of outbreeding species decreased more rapidly with island size than did those of inbreeders. Comparing species with similar ecology (e.g. ambrosia beetles) showed that this difference was best explained by differential success in colonization, rather than by differences in resource utilization or sampling biases. This conclusion was further supported by analyses of data from small islands, which suggested that outbreeding species have a higher degree of endemism and that inbreeding species are generally more widespread. 4,Recently established small populations necessarily go through a period of severe inbreeding, which should affect inbreeding species much less than outbreeding ones. In addition, non-genetic ecological and behavioural (,Allee') effects are also expected to reduce the success of outbreeding colonists much more than that of inbreeders: compared with inbreeders, outbreeders are expected to have slower growth rates, have greater difficulties with mate-location and be vulnerable to random extinction over a longer period. [source] Are hybridogenetic complexes structured by habitat in water frogs?JOURNAL OF EVOLUTIONARY BIOLOGY, Issue 6 2005S. PLENET Abstract The success and the evolutionary fate of hybridogenetic lineages are explained by both a generalistic heterosis hypothesis and an alternative hypothesis, the habitat segregation hypothesis. Because such hypotheses have rarely been tested at the level of whole habitats, our aim was to compare performances of two taxa within a hybridogenetic complex across diverse natural habitats. We took advantage of the waterfrog hybridogenetic complex (Rana esculenta and R. lessonae) by rearing tadpoles in natural contrasted habitats by means of enclosure experiments. We also monitored the frequency of each taxon in the waterfrog assemblages that naturally breed in the studied ponds. The hybridogenenetic taxon showed no evidence of broader tolerance as growth, development and physiology strongly varied in response to environmental heterogeneity. Our study reveals a differential success of the hybridogenetic taxon and its sexual host among environments. Moreover, hybridogenetic taxa rarely dominated the sexual species in natural assemblages. Consequently, our results show that the generalistic model does not explain the success of hybridogenetic lineages, but rather support the habitat segregation, among other alternative concepts. [source] Is there Nationalism after Ernest Gellner?NATIONS AND NATIONALISM, Issue 4 2003An exploration of methodological choices This paper explores the advance of the study of nationalism with particular reference to hitherto neglected methodologies. After suggesting what might be the lesson to be learned from Ernest Gellner's critique of Wittgensteinian linguistic philosophy, I set out some of the considerations and questions which guide my own attempt at a definition of nationalism after Gellner. These are essentially concerned with the function of meaning for ,real people', that is, with the substantiation of the nation through the study of ideologies and feelings, links between interest and identity, conditions of responsiveness and the differential success of mass mobilisation. In the remainder of the paper, I explore the benefit that may be achieved from adopting the methodologies of the so-called Cambridge school of the history of political thought and of social representations in social psychology. [source] | ||||||||||