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Different Niches (different + niche)
Selected AbstractsForaging Behaviour of Subordinate Great Tits (Parus major).ETHOLOGY, Issue 10 2001Can Morphology Reduce the Cost of Subordination? This paper studies the magnitude of the behavioural shift, from forage standing to forage hanging, of subordinate great tits (Parus major) in two different social contexts: feeding solitarily vs. feeding with a dominant conspecific. The aim is to test the hypothesis that differences in morphological design provide subordinates with varying abilities to reduce the presumed costs of subordination. We find that different subordinate individuals change the foraging behaviour, occupying a different niche when an intra-specific competitor is present. Morphology linked to sexual dimorphism, specifically body mass, is the factor responsible for the different magnitudes of change. Lighter subordinates can remain longer than heavier ones at the feeding patch without interrupting their foraging. Thereby, the former reduce the costs of being subordinate more than the latter. Among subordinates, females are lighter than males; they also spend more time feeding in the presence of a dominant conspecific than males do. No differences are found between age categories. We find no relationship between tarsus length and individual ecological plasticity. Our results support the idea that the ecological plasticity due to morphological differences is a mechanism that allows subordinate individuals to overcome costs associated with subordination. [source] Model-based uncertainty in species range predictionJOURNAL OF BIOGEOGRAPHY, Issue 10 2006Richard G. Pearson Abstract Aim, Many attempts to predict the potential range of species rely on environmental niche (or ,bioclimate envelope') modelling, yet the effects of using different niche-based methodologies require further investigation. Here we investigate the impact that the choice of model can have on predictions, identify key reasons why model output may differ and discuss the implications that model uncertainty has for policy-guiding applications. Location, The Western Cape of South Africa. Methods, We applied nine of the most widely used modelling techniques to model potential distributions under current and predicted future climate for four species (including two subspecies) of Proteaceae. Each model was built using an identical set of five input variables and distribution data for 3996 sampled sites. We compare model predictions by testing agreement between observed and simulated distributions for the present day (using the area under the receiver operating characteristic curve (AUC) and kappa statistics) and by assessing consistency in predictions of range size changes under future climate (using cluster analysis). Results, Our analyses show significant differences between predictions from different models, with predicted changes in range size by 2030 differing in both magnitude and direction (e.g. from 92% loss to 322% gain). We explain differences with reference to two characteristics of the modelling techniques: data input requirements (presence/absence vs. presence-only approaches) and assumptions made by each algorithm when extrapolating beyond the range of data used to build the model. The effects of these factors should be carefully considered when using this modelling approach to predict species ranges. Main conclusions, We highlight an important source of uncertainty in assessments of the impacts of climate change on biodiversity and emphasize that model predictions should be interpreted in policy-guiding applications along with a full appreciation of uncertainty. [source] Interactions of Temperament and Culture: The Organization of Diversity in Samoan InfancyETHOS, Issue 2 2009Harold L. Odden Although most are minor adaptations, some culturally patterned adjustments can have profound organizational effects on the niche and the child's developmental trajectory. Research conducted in Samoa suggests at least two distinct adaptations of the modal developmental niche for infants and toddlers keyed to different temperamental profiles: interpersonally assertive and behaviorally restrained. I argue that these two different variants of the modal niche emerge from dynamic interplay of different temperamental profiles, ethnotheories of child development, and child-rearing practices. These different niches can be developmentally significant in that they channel the individual's development in contrastive ways and introduce different future developmental challenges and opportunities. My larger point is that these different manifestations of the developmental niche represent one way in which social, cultural, and ecological factors on the one hand, and individual diversity on the other hand, interact to organize and constrain individual diversity. [Child development, temperament, infancy, developmental niche, Samoa] [source] SELECTION IN HETEROGENEOUS ENVIRONMENTS MAINTAINS THE GENE ARRANGEMENT POLYMORPHISM OF DROSOPHILA PSEUDOOBSCURAEVOLUTION, Issue 12 2008Stephen W. Schaeffer Chromosomal rearrangements may play an important role in how populations adapt to a local environment. The gene arrangement polymorphism on the third chromosome of Drosophila pseudoobscura is a model system to help determine the role that inversions play in the evolution of this species. The gene arrangements are the likely target of strong selection because they form classical clines across diverse geographic habitats, they cycle in frequency over seasons, and they form stable equilibria in population cages. A numerical approach was developed to estimate the fitness sets for 15 gene arrangement karyotypes in six niches based on a model of selection,migration balance. Gene arrangement frequencies in the six different niches were able to reach a stable meta-population equilibrium that matched the observed gene arrangement frequencies when recursions used the estimated fitnesses with a variety of initial inversion frequencies. These analyses show that a complex pattern of selection is operating in the six niches to maintain the D. pseudoobscura gene arrangement polymorphism. Models of local adaptation predict that the new inversion mutations were able to invade populations because they held combinations of two to 13 local adaptation loci together. [source] Lystrosaurus species composition across the Permo,Triassic boundary in the Karoo Basin of South AfricaLETHAIA, Issue 2 2007JENNIFER BOTHA Lystrosaurus is one of the few therapsid genera that survived the end-Permian mass extinction, and the only genus to have done so in abundance. This study identifies which species of Lystrosaurus have been recovered from Permian and Triassic strata to determine changes in the species composition across the Permo,Triassic (P,T) boundary in the Karoo Basin of South Africa. Data generated from museum collections and recent fieldwork were used to stratigraphically arrange a total of 189 Lystrosaurus specimens to determine which species survived the extinction event. Results reveal that L. curvatus and L. maccaigi lived together on the Karoo floodplains immediately before the extinction event. L. maccaigi did not survive into the Triassic in South Africa. L. curvatus survived, but did not flourish and soon became extinct. Two new species of Lystrosaurus, L. murrayi and L. declivis, appeared in the Early Triassic. It is possible that L. murrayi and L. declivis occupied different niches to L. maccaigi and L. curvatus, and had special adaptations that were advantageous in an Early Triassic environment. We suggest that L. maccaigi may be used as a biostratigraphic marker to indicate latest Permian strata in South Africa and that, in support of previous proposals, the genus Lystrosaurus should not be used as a sole indicator of Triassic-aged strata. Our field data also show that L. curvatus may be regarded as a biostratigraphic indicator of the P,T boundary interval. [source] Novel experimental Pseudomonas aeruginosa lung infection model mimicking long-term host,pathogen interactions in cystic fibrosisAPMIS, Issue 2 2009CLAUS MOSER The dominant cause of premature death in patients suffering from cystic fibrosis (CF) is chronic lung infection with Pseudomonas aeruginosa. The chronic lung infection often lasts for decades with just one clone. However, as a result of inflammation, antibiotic treatment and different niches in the lungs, the clone undergoes significant genetic changes, resulting in diversifying geno- and phenotypes. Such an adaptation may generate different host responses. To experimentally reflect the year-long chronic lung infection in CF, groups of BALB/c mice were infected with clonal isolates from different periods (1980, 1988, 1997, 1999 and 2003) of the chronic lung infection of one CF patient using the seaweed alginate embedment model. The results showed that the non-mucoid clones reduced their virulence over time, resulting in faster clearing of the bacteria from the lungs, improved pathology and reduced pulmonary production of macrophage inflammatory protein-2 (MIP-2) and granulocyte colony-stimulating factor (G-CSF). In contrast, the mucoid clones were more virulent and virulence increased with time, resulting in impaired pulmonary clearing of the latest clone, severe inflammation and increased pulmonary MIP-2 and G-CSF production. In conclusion, adaptation of P. aeruginosa in CF is reflected by changed ability to establish lung infection and results in distinct host responses to mucoid and non-mucoid phenotypes. [source] | |||||||||||||