20 research outputs found
Modeling Ecosystems Using P Systems: The Bearded Vulture, a Case Study
The Bearded Vulture (Gypaetus barbatus) is an endangered
species in Europe that feeds almost exclusively on bone remains of wild
and domestic ungulates. In this paper, we present a model of an ecosystem
related to the Bearded Vulture in the Pyrenees (NE Spain), by
using P systems. The evolution of six species is studied: the Bearded
Vulture and five subfamilies of domestic and wild ungulates upon which
the vulture feeds. P systems provide a high level computational modeling
framework which integrates the structural and dynamic aspects of
ecosystems in a comprehensive and relevant way. P systems explicitly
represent the discrete character of the components of an ecosystem by
using rewriting rules on multisets of objects which represent individuals
of the population and bones. The inherent stochasticity and uncertainty
in ecosystems is captured by using probabilistic strategies. In order to
experimentally validate the P system designed, we have constructed a
simulator that allows us to analyze the evolution of the ecosystem under
different initial conditions.Ministerio de Educación y Ciencia TIN2006-13425Junta de Andalucía TIC-58
Nurses' perceptions of aids and obstacles to the provision of optimal end of life care in ICU
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Is response to fire influenced by dietary specialization and mobility? A comparative study with multiple animal assemblages
Fire is a major agent involved in landscape transformation and an indirect cause of changes in species composition. Responses to fire may vary greatly depending on life histories and functional traits of species. We have examined the taxonomic and functional responses to fire of eight taxonomic animal groups displaying a gradient of dietary and mobility patterns: Gastropoda, Heteroptera, Formicidae, Coleoptera, Araneae, Orthoptera, Reptilia and Aves. The fieldwork was conducted in a Mediterranean protected area on 3 sites (one unburnt and two burnt with different postfire management practices) with five replicates per site. We collected information from 4606 specimens from 274 animal species. Similarity in species composition and abundance between areas was measured by the Bray-Curtis index and ANOSIM, and comparisons between animal and plant responses by Mantel tests. We analyze whether groups with the highest percentage of omnivorous species, these species being more generalist in their dietary habits, show weak responses to fire (i.e. more similarity between burnt and unburnt areas), and independent responses to changes in vegetation. We also explore how mobility, i.e. dispersal ability, influences responses to fire. Our results demonstrate that differences in species composition and abundance between burnt and unburnt areas differed among groups. We found a tendency towards presenting lower differences between areas for groups with higher percentages of omnivorous species. Moreover, taxa with a higher percentage of omnivorous species had significantly more independent responses of changes in vegetation. High- (e.g. Aves) and low-mobility (e.g. Gastropoda) groups had the strongest responses to fire (higher R scores of the ANOSIM); however, we failed to find a significant general pattern with all the groups according to their mobility. Our results partially support the idea that functional traits underlie the response of organisms to environmental changes caused by fire
Habitat and reproductive phenology of wild boar (Sus scrofa) in the western Iberian Peninsula
We examined the reproductive phenology of wild boar populations in four regions of the western Iberian Peninsula during the 1999/2000 hunting season (October-February). To estimate conception dates and birth distribution frequencies, we used foetal weights. Regions differed significantly, and we detected a relationship between region and birth distribution frequencies. Throughout the year, food availability had a major influence on the distribution of farrowing. Although a short period of high food availability leads to highly synchronous births, even in relatively harsh environmental conditions, adult females that exploit low-quality food items appear to be able to give birth at any time of the year.PAMAF program - project PCNA/BIA/184/96PRAXIS program - grant XXI-BD/13394/9