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Registros recuperados: 5
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Cost distance defined by a topological function of landscape Inra
Foltête, J.C.; Berthier, K.; Cosson, J.F..
Distance is a basic concept in the domain of animal species motion. Cost distances, rather than Euclidian distances, are more and more used in order to have a more realistic measure, on the basis of resistance values assigned to each landscape class. We propose here a method to compute resistance values by using topological functions of landscape, i.e. by taking account of the proximity of habitat/non-habitat edges, with continuous functions. An example is given when comparing cost distances and the propagation of water vole in the massif of Jura (France). The comparison with usual cost distances gives information about the ecological assumptions. The results show also that the statistical behaviour of the distances depending of the parameters of the...
Tipo: Journal Article Palavras-chave: ECOLOGIE DES POPULATIONS; DISTANCE-COUT; BORDURE COST DISTANCE; RESISTANCE; EDGE; HABITAT; SPREAD; WATER VOLE.
Ano: 2008 URL: http://www.prodinra.inra.fr/prodinra/pinra/doc.xsp?id=PROD20091111fb4&uri=/notices/prodinra1/2009/03/
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Density-related changes in selection pattern for major histocompatibility complex genes in fluctuating populations of voles Inra
Bryja, J.; Charbonnel, N.; Berthier, K.; Galan, M.; Cosson, J.F..
Host-pathogen interactions are of particular interest in studies of the interplay between population dynamics and natural selection. The major histocompatibility complex (MHC) genes of demographically fluctuating species are highly suitable markers for such studies, because they are involved in initiating the immune response against pathogens and display a high level of adaptive genetic variation. We investigated whether two MHC class II genes (DQA1, DRB) were subjected to contemporary selection during increases in the density of fossorial water vole (Arvicola terrestris) populations, by comparing the neutral genetic structure of seven populations with that estimated from MHC genes. Tests for heterozygosity excess indicated that DQA1 was subject to intense...
Tipo: Journal Article Palavras-chave: BALANCING SELECTION; LOCAL ADAPTATION; MHC; MAJOR HISTOINCOMPATIBILITY COMPLEX; POPULATION CYCLES.
Ano: 2007 URL: http://www.prodinra.inra.fr/prodinra/pinra/doc.xsp?id=PROD200986a4a82d&uri=/notices/prodinra1/2010/08/
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Modeling survival and mark loss in molting animals using capture, dead recoveries and exuvia recoveries Inra
Besnard, A.; Piry, S.; Berthier, K.; Lebreton, J.D.; Streiff, R..
Capture-mark-recapture (CMR) analyses aim primarily at estimating relevant life history parameters, despite the fact that some individuals are not always recaptured, even if alive on the study site. Applying such approaches to species with a complex life cycle, such as insects, remains challenging because each change of stage tends to cause mark loss through molting. We developed a multistate model based on three exclusive events ("dead,'' "surviving and molting,'' and "surviving and staying in the same larval stage'') to estimate probabilities of survival and mark loss. Estimates of biologically relevant parameters were derived from those of the probabilities of transition between these states. The model was applied to data from radio-tracking diodes...
Tipo: Journal Article Palavras-chave: PROBABILITE DE SURVIE; PRIONOTROPIS Hystrix RHODANICA.
Ano: 2007 URL: http://www.prodinra.inra.fr/prodinra/pinra/doc.xsp?id=PROD2008a5935d7c&uri=/notices/prodinra1/2009/01/
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Multiple parasites mediate balancing selection at two MHC class II genes in the fossorial water vole: insights from multivariate analyses and population genetics Inra
Tollenaere, C.; Bryja, J.; Galan, M.; Cadet, P.; Deter, J.; Chaval, Y.; Berthier, K.; Ribas Salvador, A.; Voutilainen, L.; Laakkonens, J.; Cosson, J.F.; Charbonnel, N..
We investigated the factors mediating selection acting on two MHC class II genes (DQA and DRB) in water vole (Arvicola scherman) natural populations in the French Jura Mountains. Population genetics showed significant homogeneity in allelic frequencies at the DQA1 locus as opposed to neutral markers (nine microsatellites), indicating balancing selection acting on this gene. Moreover, almost exhaustive screening for parasites, including gastrointestinal helminths, brain coccidia and antibodies against viruses responsible for zoonoses, was carried out. We applied a co-inertia approach to the genetic and parasitological data sets to avoid statistical problems related to multiple testing. Two alleles, Arte-DRB-11 and Arte-DRB-15, displayed antagonistic...
Tipo: Journal Article Palavras-chave: IMMUNOGENETIQUE; CO-INERTIE; GENES MHC; ANALYSE MULTIVARIEE CO-INERTIA; DQA AND DRB MHC GENES; IMMUNOGENETICS; MULTIVARIATE ANALYSIS; PARASITE-MEDIATED BALANCING SELECTION.
Ano: 2008 URL: http://www.prodinra.inra.fr/prodinra/pinra/doc.xsp?id=PROD20091657fa4b&uri=/notices/prodinra1/2011/06/
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Stress and demographic decline: a potential effect mediated by impairment of reproduction and immune function in cyclic vole populations Inra
Charbonnel, N.; Chaval, Y.; Berthier, K.; Deter, J.; Morand, S.; Palme, R.; Cosson, J.F..
The stress response is initially adaptive, operating to maintain homeostasis. However, chronic long-term exposure to stressors may have detrimental effects. We proposed that chronic stress may be a major factor in demographic vole cycles, inducing decline in high-density populations. We monitored four populations of the fossorial water vole Arvicola scherman, which undergo pluriannual demographic cycles in the Jura Mountains (France). Sampling was conducted during the high densities and the decline. We measured fecal corticosterone metabolites (FCMs) to assess stress levels and injected phytohemagglutinin to estimate the cell-mediated immune response. We demonstrated that stress levels increase between the high densities and the decline in most of the vole...
Tipo: Journal Article Palavras-chave: DECLIN DEMOGRAPHIQUE; CORTICOSTERONE  ; RODENT; DEMOGRAPHIC DECLINE; STRESS; POPULATION DYNAMICS.
Ano: 2008 URL: http://www.prodinra.inra.fr/prodinra/pinra/doc.xsp?id=PROD2009776ecbf8&uri=/notices/prodinra1/2009/03/
Registros recuperados: 5
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