Estimación de la contribución de la supervivencia y del reclutamiento en la dinámica de poblaciones a gran escala

At large spatial scales, variation in population abundance results from variation in the survival of reproducing adults and variation in the recruitment of new individuals. Which of these two parameters varies the most and how these parameters are correlated are fundamental questions if we want to understand the large–scale dynamics of such populations. I explore how Pradel’s seniority (complement of the proportion of new individuals in the population) may help to answer such questions. I show that the sign of the correlation between temporal variation in seniority and of an independent measure of population growth rate should indicate whether population growth rate is more influenced by variation in survival or by variation in recruitment. Various predictions are proposed for evaluating the degree of regulation in the population (i.e., the existence of a negative correlation between survival and recruitment). Data from the French integrated breeding bird monitoring programme, combining point count surveys, from which population growth rate is estimated, and standardized capture–recapture, allowing the estimation of survival and seniority variation, were used to evaluate the method. Patterns of variation were examined for the four most frequently captured species, using data from 32 trapping sites covering 13 years (1989–2001). For Blackcap and Chiffchaff, the pattern is consistent with population growth rate being under the additive influence of survival and recruitment. For the Reed Warbler, the population appears to be strongly regulated, but with recruitment unable to compensate entirely for survival variation. For the Blackbird, the pattern is more confused and may indicate complex population dynamics, with non–linear relationships between survival, recruitment and population growth rate. Altogether, the method appears extremely promising and is particularly suitable for large scale monitoring of breeding birds by means of ringing.A grandes escalas espaciales, la variación en la abundancia poblacional se produce como consecuencia de la variación en la supervivencia de los adultos en edad reproductora y la variación en el reclutamiento de nuevos individuos. Para comprender la dinámica a gran escala de estas poblaciones es fundamental conocer cuál de estos dos parámetros varía en mayor medida y de qué modo se correlacionan entre sí. En el presente estudio se analiza cómo el modelo de senescencia de Pradel (complemento del porcentaje de individuos nuevos en la población) puede contribuir a responder estas preguntas. Se demuestra que el signo de la correlación entre la variación temporal en la senescencia y el de una medición independiente de la tasa de crecimiento poblacional debería indicar si la tasa de crecimiento poblacional está más influenciada por la variación en la supervivencia o por la variación en el reclutamiento. Se proponen varias predicciones para evaluar el grado de regulación de la población (es decir, la existencia de una correlación negativa entre la supervivencia y el reclutamiento). Para evaluar este método se utilizaron datos del programa francés de seguimiento integral de aves en edad reproductora, en combinación con estudios de recuento de puntos, lo que permite estimar la tasa de crecimiento poblacional, así como la captura–recaptura estandarizada, que permite estimar la variación en la supervivencia y la senescencia. Se examinaron pautas de variación para las cuatro especies capturadas con mayor frecuencia, empleando datos de 32 localidades de trampeo a lo largo de un período de 13 años (1989–2001). Para la curruca capirotada y el mosquitero común, la pauta concuerda con una tasa poblacional sujeta a la influencia aditiva de la supervivencia y el reclutamiento. Para el carricero común, la población parece estar fuertemente controlada, si bien el reclutamiento no puede compensar por completo la variación en la supervivencia. Para el mirlo común, la pauta es más confusa, pudiendo indicar una dinámica poblacional compleja, con relaciones no lineales entre la supervivencia, el reclutamiento y la tasa de crecimiento poblacional. En conjunto, el método parece extremadamente prometedor y resulta muy adecuado para el seguimiento a gran escala de aves en edad reproductora por medio del anillamiento

Exploración de los modelos de marcaje–reavistaje–recuperación para estudiar la demografía de los árboles de sabana

Despite their sessile nature, juvenile trees in savannah ecosystems are not always easy to encounter. Here, we evaluate the applicability to plants of the remedy of choice in animal studies: capture–recapture modelling. The plant equivalents, tagging and resighting, were caried outnin 7 censuses, involving 4,145 juvenile trees of 8 dominant savannah species. Using models with joint analysis of live and dead encounters, the resighting probabilities averaged 0.88 ± 0.15 and 0.92 ± 0.10 for seedlings and resprouts respectively; while dead recovery probabilities averaged 0.71 ± 0.25 for all age–classes. An ad hoc method that did not take into account encounter probabilities yielded biased survival estimates compared with estimates obtained using the mark–resighting–recovery approaches. This bias was observed even at high encounter probabilities, and we recommend therefore capture–recapture models where plant encounter is less than one. Finally, survival probabilities estimated by models based only on live or on dead data might both differ and be less accurate than estimates based on combined data. This highlights the advantages of models with joint analysis of live and dead encounters even the value of site fidelity is one.Pese a su naturaleza sésil, los árboles jóvenes no siempre resultan fáciles de hallar en los ecosistemas de sabana. En el presente trabajo se evalua la odelización de captura–recaptura, tan utilizada en estudios de animales, para su aplicación en los estudios de plantas. El equivalente al marcaje y reavistamiento para las plantas, se llevó a cabo a lo largo de siete censos, con un total de 4.145 árboles juveniles de ocho especies de la sabana dominantes. Mediante el empleo de análisis conjuntos de hallazgos de individuos vivos y muertos, las probabilidades de reaviastamiento medias fueron de 0,88 ± 0,15 y 0,92 ± 0,10 para las plántulas y los rebrotes, respectivamente, mientras que el promedio correspondiente a las probabilidades de recuperación de individuos muertos fue de 0,71 ± 0,25 para todas las clases de edad. Un método especialmente disenyado que no tenía en cuenta las probabilidades de recaptura dio unas estimaciones de supervivencia sesgadas, en comparación con las estimas obtenidas utilizando las aproximaciones basadas en el marcaje–reavistamiento–recaptura. Este sesgo aparecía incluso con altas probabilidades de recaptura, por lo que recomendamos los modelos de captura–recaptura en los que la probabilidad de encontarr la planta es menor de uno. Por ultimo, las probabilidades de supervivencia estimadas mediante los modelos basados únicamente en datos de plantas vivas o muertas pueden tanto diferir como ser menos precisas que las estimas basadas en datos combinados. Esto realza las ventajas de los modelos que emplean análisis conjuntos de hallazgos de plantas vivas y muertas, aun cuando el valor de la fidelidad al emplazamiento sea uno

La réaction d ’hémagglutination type Middlebrook-Dubos dans le diagnostic de la tuberculose bovine

La réaction d’hémagglutination type Middlebrook- Dubos, effectuée chez 118 bovins avec des hématies de mouton et la tuberculine soit dite « précipitée » soit I.P. 48 de l ’Institut Pasteur de Paris, a été positive dans 81 p. 100 des cas de tuberculose évolutive, avec des pourcentages variables selon la nature des lésions puisqu’elle a été maxima (100 p. 100) pour les lésions pleuro-pulmonaires, forte (87,3 p. 100) pour les lésions de plusieurs organes ou généralisées, et faible (50 p. 100) pour les lésions ganglio-pulmonaires . Par contre, elle a été le plus souvent négative lorsque les lésions étaient limitées aux ganglions pulmonaires et de type caséo-calcaire. Cette réaction a été très rarement (4,0 p. 100) positive chez des animaux apparemment sains, et toujours d’ailleurs à des taux faibles. Bien que des recherches portant sur de nombreux sérums soient encore nécessaires (pour préciser en particulier la signification des réactions positives chez les bovidés apparemment sains), on peut admettre, semble-t-il, dès maintenant, qu’une réaction nettement positive (5> 1/147) traduit toujours une tuberculose évolutive atteignant plusieurs organes. Elle paraît pouvoir dès maintenant rendre des services pour le diagnostic de la tuberculose et l’étude de la phtisiogenèse chez les bovidés

SICANE: a Detector Array for the Measurement of Nuclear Recoil Quenching Factors using Monoenergetic Neutron Beam

SICANE is a neutron scattering multidetector facility for the determination of the quenching factor (ratio of the response to nuclear recoils and to electrons) of cryogenic detectors used in direct WIMP searches. Well collimated monoenergetic neutron beams are obtained with inverse (p,n) reactions. The facility is described, and results obtained for the quenching factors of scintillation in NaI(Tl) and of heat and ionization in Ge are presented.Comment: 30 pages, Latex, 11 figures. Submitted to NIM

Dark Matter Search in the Edelweiss Experiment

Preliminary results obtained with 320g bolometers with simultaneous ionization and heat measurements are described. After a few weeks of data taking, data accumulated with one of these detectors are beginning to exclude the upper part of the DAMA region. Prospects for the present run and the second stage of the experiment, EDELWEISS-II, using an innovative reversed cryostat allowing data taking with 100 detectors, are briefly described.Comment: IDM 2000, 3rd International Workshop on the Identification of Dark Matter, York (GB), 18-22/09/2000, v2.0 minor modification

Identification of backgrounds in the EDELWEISS-I dark matter search experiment

This paper presents our interpretation and understanding of the different backgrounds in the EDELWEISS-I data sets. We analyze in detail the several populations observed, which include gammas, alphas, neutrons, thermal sensor events and surface events, and try to combine all data sets to provide a coherent picture of the nature and localisation of the background sources. In light of this interpretation, we draw conclusions regarding the background suppression scheme for the EDELWEISS-II phase

Measurement of the response of heat-and-ionization germanium detectors to nuclear recoils

The heat quenching factor Q' (the ratio of the heat signals produced by nuclear and electron recoils of equal energy) of the heat-and-ionization germanium bolometers used by the EDELWEISS collaboration has been measured. It is explained how this factor affects the energy scale and the effective quenching factor observed in calibrations with neutron sources. This effective quenching effect is found to be equal to Q/Q', where Q is the quenching factor of the ionization yield. To measure Q', a precise EDELWEISS measurement of Q/Q' is combined with values of Q obtained from a review of all available measurements of this quantity in tagged neutron beam experiments. The systematic uncertainties associated with this method to evaluate Q' are discussed in detail. For recoil energies between 20 and 100 keV, the resulting heat quenching factor is Q' = 0.91+-0.03+-0.04, where the two errors are the contributions from the Q and Q/Q' measurements, respectively. The present compilation of Q values and evaluation of Q' represent one of the most precise determinations of the absolute energy scale for any detector used in direct searches for dark matter.Comment: 28 pages, 7 figures. Submitted to Phys. Rev.

Final results of the EDELWEISS-II WIMP search using a 4-kg array of cryogenic germanium detectors with interleaved electrodes

The EDELWEISS-II collaboration has completed a direct search for WIMP dark matter with an array of ten 400-g cryogenic germanium detectors in operation at the Laboratoire Souterrain de Modane. The combined use of thermal phonon sensors and charge collection electrodes with an interleaved geometry enables the efficient rejection of gamma-induced radioactivity as well as near-surface interactions. A total effective exposure of 384 kg.d has been achieved, mostly coming from fourteen months of continuous operation. Five nuclear recoil candidates are observed above 20 keV, while the estimated background is 3.0 events. The result is interpreted in terms of limits on the cross-section of spin-independent interactions of WIMPs and nucleons. A cross-section of 4.4x10^-8 pb is excluded at 90%CL for a WIMP mass of 85 GeV. New constraints are also set on models where the WIMP-nucleon scattering is inelastic.Comment: 23 pages, 5 figures; matches published versio

A search for low-mass WIMPs with EDELWEISS-II heat-and-ionization detectors

We report on a search for low-energy (E < 20 keV) WIMP-induced nuclear recoils using data collected in 2009 - 2010 by EDELWEISS from four germanium detectors equipped with thermal sensors and an electrode design (ID) which allows to efficiently reject several sources of background. The data indicate no evidence for an exponential distribution of low-energy nuclear recoils that could be attributed to WIMP elastic scattering after an exposure of 113 kg.d. For WIMPs of mass 10 GeV, the observation of one event in the WIMP search region results in a 90% CL limit of 1.0x10^-5 pb on the spin-independent WIMP-nucleon scattering cross-section, which constrains the parameter space associated with the findings reported by the CoGeNT, DAMA and CRESST experiments.Comment: PRD rapid communication accepte