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91.
CHRISTINE DEMANCHE FANELIE WANERT NICOLAS HERRENSCHMIDT CLAIRE MOUSSU ISABELLE DURAND-JOLY EDUARDO DEI-CAS RENE CHERMETTE JACQUES GUILLOT 《The Journal of eukaryotic microbiology》2003,50(S1):611-613
ABSTRACT. As monkeys-derived Pneumocystis is closely related to P. jirovecii , simian populations should be considered as valuable models for the understanding of the epidemiology of human pneumocystosis. In the present study, the impact of environmental factors on the carriage of Pneumocystis was evaluated in socially organized group of immunocoinpetent macaques (Macuca fascicularis). The tribe, maintained in partial release al the Primatology Center of Strasbourg in France, comprised 29 animals at the end of the study. From December 2000 to November 2002, deep nasal swab samples were collected monthly from each animal under general anaesthesia. The presence of Pneurmocystis DNA was assessed by nested PCR of mtLSU rRNA gene. No case of pneumocystosis was reported during the study. Pneumocystis DNA was detected in 166 out 01 481 swab samples examined (34.5%). The number of macaques with detectable Pneumocystis DNA was highly variable from one month to another. However, Pneumocystis carriage was clearly correlated to the mean precipitation rates. 相似文献
92.
SBASTIEN VERNE NICOLAS PUILLANDRE GRALDINE BRUNET NICOLAS GOUIN PAUL B. SAMOLLOW JOEL D. ANDERSON FRDRIC GRANDJEAN 《Molecular ecology resources》2006,6(2):328-330
The common pill bug, Armadillidium vulgare, is known to harbour two distinct strains of the feminizing proteobacteria Wolbachia. In order to study the effect of the presence of Wolbachia on the evolution of A. vulgare populations, we developed and characterized a set of nine polymorphic microsatellite loci from two microsatellite‐enriched genomic libraries. We screened 48 individuals from three French populations and found high genetic variation. Locus‐specific allelic diversity ranged from four to 28 and observed heterozygosity from 0.40 to 1.00, which indicates that these markers can be used to conduct population genetic studies in A. vulgare. 相似文献
93.
NICOLAS GOUIN CATHERINE SOUTY‐GROSSET JÉSSICA BÓRQUEZ ANGÉLINE BERTIN FRÉDÉRIC GRANDJEAN 《Freshwater Biology》2011,56(10):2105-2118
1. Habitat fragmentation of stream ecosystems often results in decreased connectivity between populations and lower population sizes. Hence, understanding how habitat fragmentation affects genetic erosion is important for the preservation of freshwater biodiversity, in particular, as small populations suffer from loss of genetic diversity through genetic drift and loss of fitness because of inbreeding, increasing the risk of extinction. 2. Here, we assess the impact of demographic factors on population differentiation in the endangered freshwater crayfish Austropotamobius pallipes by analysing population genetic structure, estimating effective population sizes and comparing levels of polymorphism at five microsatellite loci with density estimates of 10 populations within a small French catchment that has become progressively confined to headwaters over the last six decades. 3. Levels of expected heterozygosity and allelic richness per population were relatively low (0.214–0.396 and 1.6–2.6, respectively). We found strong genetic differentiation between these geographically close populations (FST = 0.283), with weak statistical evidence for a pattern of isolation by distance. Estimates of effective population size were low (<150) in most populations, but potentially reached several thousands in three populations. 4. Population density and allelic richness were strongly positively correlated. A robust relationship between population density and heterozygosity values was also noted, but only after discarding two populations for which significant genetic signatures of a recent bottleneck were found; these two populations displayed high expected heterozygosity compared with a very low density. Populations with the highest densities of individuals had the highest effective population size estimates and vice versa. 5. Our results clearly show the importance of demographic factors and genetic drift on A. pallipes populations. Furthermore, analysis of genetic and population density data is a pragmatic and efficient approach to corroborate inferences from genetic data and can be particularly useful in the identification of populations experiencing a bottleneck and therefore in conservation genetics studies aiming at identifying priority populations for conservation. 相似文献
94.
BRUNO CARGNELUTTI AURÉLIE COULON A.J. MARK HEWISON MICHEL GOULARD JEAN-MARC ANGIBAULT NICOLAS MORELLET 《The Journal of wildlife management》2007,71(4):1380-1387
Abstract: To determine the spatial resolution of Global Positioning System (GPS) receiver data, rigorous testing is essential. We tested performance of the Lotek 3300 GPS collar for medium-sized mammals (Lotek Engineering, Inc., Newmarket, ON, Canada). To mimic real wildlife monitoring situations, we performed both static (stationary receiver) and mobile tests, placing the receiver collar on a dog. We compared fix locations of the mobile receiver with the actual trajectory described by a portable Trimble high-precision GPS. We determined performance in relation to habitat type and leaf cover. Location error was habitat-dependent, with the best results in open habitat and much poorer ones in forest, particularly coniferous-dominated forest. For both static and mobile tests, location accuracy was higher when the number of satellites contacted was high and when the residual positional dilution of precision (PDOP) value was low. However, location error was highly variable, even for a given PDOP value and a given number of satellites contacted. Finally, mobile collars performed less well than their static counterparts, presumably because of frequent changes of GPS position and orientation. 相似文献
95.
MICHAEL J. LIDDELL NICOLAS NIEULLET OTVIO C. CAMPOE MARTIN FREIBERG 《Austral ecology》2007,32(1):43-58
Abstract Current estimates of the total biomass in tropical rainforests vary considerably; this is due in large part to the different approaches that are used to calculate biomass. In this study we have used a canopy crane to measure the tree architectures in a 1 ha plot of complex mesophyll vine forest at Cape Tribulation, Australia. Methods were developed to measure and calculate the crown and stem biomass of six major species of tree and palm (Alstonia scholaris (Apocynaceae), Cleistanthus myrianthus (Euphorbiaceae), Endiandra microneura (Lauraceae), Myristica insipida (Myristicaceae), Acmena graveolens (Myrtaceae), Normanbya normanbyi (Arecaceae)) using the unique access provided by the crane. This has allowed the first non‐destructive biomass estimate to be carried out for a forest of this type. Allometric equations which relate tree biomass to the measured variable ‘diameter at breast height’ were developed for the six species, and a general equation was also developed for trees on the plot. The general equation was similar in form to equations developed for tropical rainforests in Brazil and New Guinea. The species equations were applied at the level of families, the generalized equation was applied to the remaining species which allowed the biomass of a total of 680 trees to be calculated. This has provided a current estimate of 270 t ha−1 above‐ground biomass at the Australian Canopy Crane site; a value comparable to lowland rainforests in Panama and French Guiana. Using the same tree database seven alternative allometric equations (literature equations for tropical rainforests) were used to calculate the site biomass, the range was large (252–446 t ha−1) with only three equations providing estimates within 34 t ha−1 (12.5%) of the site value. Our use of multiple species‐specific allometric equations has provided a site estimate only slightly larger (1%) than that obtained using allometric equations developed specifically for tropical wet rainforests. We have demonstrated that it is possible to non‐destructively measure the biomass in a complex forest using an on‐site canopy crane. In conjunction the development of crown maps and a detailed tree architecture database allows changes in forest structure to be followed quantitatively. 相似文献
96.
LAËTITIA BUISSON WILFRIED THUILLER NICOLAS CASAJUS SOVAN LEK GAËL GRENOUILLET 《Global Change Biology》2010,16(4):1145-1157
Species distribution modelling has been widely applied in order to assess the potential impacts of climate change on biodiversity. Many methodological decisions, taken during the modelling process and forecasts, may, however, lead to a large variability in the assessment of future impacts. Using measures of species range change and turnover, the potential impacts of climate change on French stream fish species and assemblages were evaluated. Our main focus was to quantify the uncertainty in the projections of these impacts arising from four sources of uncertainty: initial datasets (Data), statistical methods [species distribution models (SDM)], general circulation models (GCM), and gas emission scenarios (GES). Several modalities of the aforementioned uncertainty sources were combined in an ensemble forecasting framework resulting in 8400 different projections. The variance explained by each source was then extracted from this whole ensemble of projections. Overall, SDM contributed to the largest variation in projections, followed by GCM, whose contribution increased over time equalling almost the proportion of variance explained by SDM in 2080. Data and GES had little influence on the variability in projections. Future projections of range change were more consistent for species with a large geographical extent (i.e., distribution along latitudinal or stream gradients) or with restricted environmental requirements (i.e., small thermal or elevation ranges). Variability in projections of turnover was spatially structured at the scale of France, indicating that certain particular geographical areas should be considered with care when projecting the potential impacts of climate change. The results of this study, therefore, emphasized that particular attention should be paid to the use of predictions ensembles resulting from the application of several statistical methods and climate models. Moreover, forecasted impacts of climate change should always be provided with an assessment of their uncertainty, so that management and conservation decisions can be taken in the full knowledge of their reliability. 相似文献
97.
GENTILE FRANCESCO FICETOLA LUIGI MAIORANO ALESSANDRA FALCUCCI NICOLAS DENDONCKER LUIGI BOITANI EMILIO PADOA‐SCHIOPPA CLAUDE MIAUD WILFRIED THUILLER 《Global Change Biology》2010,16(2):528-537
Biological invasions and land‐use changes are two major causes of the global modifications of biodiversity. Habitat suitability models are the tools of choice to predict potential distributions of invasive species. Although land‐use is a key driver of alien species invasions, it is often assumed that land‐use is constant in time. Here we combine historical and present day information, to evaluate whether land‐use changes could explain the dynamic of invasion of the American bullfrog Rana catesbeiana (=Lithobathes catesbeianus) in Northern Italy, from the 1950s to present‐day. We used maxent to build habitat suitability models, on the basis of past (1960s, 1980s) and present‐day data on land‐uses and species distribution. For example, we used models built using the 1960s data to predict distribution in the 1980s, and so on. Furthermore, we used land‐use scenarios to project suitability in the future. Habitat suitability models predicted well the spread of bullfrogs in the subsequent temporal step. Models considering land‐use changes predicted invasion dynamics better than models assuming constant land‐use over the last 50 years. Scenarios of future land‐use suggest that suitability will remain similar in the next years. Habitat suitability models can help to understand and predict the dynamics of invasions; however, land‐use is not constant in time: land‐use modifications can strongly affect invasions; furthermore, both land management and the suitability of a given land‐use class may vary in time. An integration of land‐use changes in studies of biological invasions can help to improve management strategies. 相似文献
98.
Fatty acids (FAs) profiles and stable isotope signatures of the ghost shrimp, Trypaea australiensis and the soldier crab, Mictyris longicarpus were determined at an unvegetated sandbank of Southport (Gold Coast, Queensland, Australia), in November 2005 and February 2006. Additionally, the FAs composition of the faeces and feeding pellets of M. longicarpus and the surface sediment at the study site were also analysed. Trypaea australiensis was found to selectively feed principally on benthic diatoms, as revealed by the high contribution of the marker lipid (20:5 (n‐3)) to tissue total FAs and the δ13C and δ15N isotopic signatures of shrimp tissues. Although the diet of T. australiensis did not change between the two sampling periods, the shrimps appeared to reduce their feeding activity in summer, presumably in relation to a restricted metabolism, as revealed by a decrease in the contribution of the microalgal markers in their tissues. The FAs composition of the tissues of the soldier crab indicated that bacteria and diatoms constituted the base of its diet (contributions of branched 15:0 and 17:0, 18:1 (n‐7) and 20:5 (n‐3)). However, the isotopic signatures of the crabs suggested that meiofauna may represent an intermediate link between the crab and these micro‐organisms. 相似文献
99.
Effect of Post-anthesis Drought on Cell Division and Starch Accumulation in Developing Wheat Grains 总被引:7,自引:1,他引:7
Wheat plants (Triticum aestivum L., cv. Warigal) were subjectedto 20 d of water deficit during the period of endosperm celldivision. Drought accentuated the differences in final grainweight between spikelets and between grains within spikelets.The distal grains of top spikelets were most affected by drought.The maximum number of endosperm cells was, respectively, 30and 40 per cent lower in basal grains and distal grains of draughtedplants. In basal grains of middle spikelets, the number of largestarch granules per cell was unaffected but the number of smallstarch granules per cell was 45 per cent lower in grains ofdraughted plants. The initiation of small starch granules wasmore affected than cell division because severe water deficitoccurred earlier during the former process than the latter.Final dry weight appeared to correlate well with the maximumnumber of endosperm cells, but depended also on the number ofstarch granules per cell. Consequently, the amount of dry matterper cell was not constant in both treatments. The concentration of sucrose per endosperm cell was lower onlyin the droughted distal grains of top spikelets. The supplyof sucrose to endosperm cells did not regulate the initiationof small starch granules. Triticum aestivum L., wheat, drought, grain growth, cell division, starch 相似文献
100.
ISABELLE CHARRIER NICOLAS MATHEVON PIERRE JOUVENTIN 《Biological journal of the Linnean Society. Linnean Society of London》2003,80(2):305-312
In pinnipeds and especially in otariids, mothers and pups develop the capacity to recognize each other's voices. Pups become able to discriminate their mother's voice a few days after birth. For females, this discrimination seems to occur earlier, probably during the few hours after parturition. However, during lactation, mothers are confronted with a major problem: the change of the characteristics of their pup's calls. To investigate this problem, we first performed an acoustic analysis of pups' calls from birth to weaning to identity the successive different versions of these calls. Secondly, we performed playback experiments just before weaning to test if females retain these different versions over a long time period. The acoustic analysis of pups' calls reveals that several characteristics of their vocalizations change with age. Playback experiments demonstrate that females still recognize all the successive immature and mature versions of their pup's calls. In our opinion, this long-term memorization seems to be a by-product of the permanent pups' voice learning from birth to weaning since no apparent adaptive benefit seems to arise from this capacity. © 2003 The Linnean Society of London, Biological Journal of the Linnean Society , 2003, 80 , 305–312. 相似文献