Search results for "SAM"
showing 10 items of 7385 documents
Effects of the temporal scale of observation on the analysis of aquatic invertebrate metacommunities
2020
The development of metacommunity theory has boosted the implementation of numerous empirical tests with field data, mostly focused on the role of spatial and environmental gradients on metacommunity organization. These studies showed an important dependence of the results on the observational scale considered, i.e., spatial grain, sampling spacing, and extent. However, few works deal with time per se as a component explaining metacommunity structure, even when data from periodic sampling are available. We suggest adding time explicitly to metacommunity analysis, but taking into account that the temporal scale of observation could affect the estimation of the relative influence of environmen…
Opportunity costs resulting from scramble competition within the choosy sex severely impair mate choosiness.
2016
12 pages; International audience; Studies on mate choice mainly focus on the evolution of signals that would maximize the probability of finding a good-quality partner. Most models of sexual selection rely on the implicit assumption that individuals can freely compare and spot the best mates in a heterogeneous population. Comparatively few studies have investigated the consequences of the mate-sampling process. Several sampling strategies have been studied from theoretical or experimental perspectives. They belong to two families of decision rules: best-of-n strategies (individuals sample n partners before choosing the best one within this pool) or threshold strategies (individuals sequenti…
Genetic structure of a patchily distributed philopatric migrant: implications for management and conservation
2017
Significant demographic fluctuations can have major genetic consequences in wild populations. The lesser kestrel (Falco naumanni) has suffered both population declines and range fragmentation during the second half of the 20th century. In this study we analysed multilocus microsatellite data to assess the genetic structure of the species. Our analysis revealed significant genetic structuring of lesser kestrel populations, not only at the cross-continental scale, but also regionally within the Central and Eastern (CE) Mediterranean region. We detected signs of genetic bottlenecks in some of the peripheral populations coupled with small effective population sizes. Values of genetic differenti…
Cryptogams signify key transitions of bacteria and fungi in Arctic sand dune succession.
2020
•Primary succession models focus on aboveground vascular plants. However, the prevalence of mosses and lichens, i.e. cryptogams, suggests they play a role in soil successions. Here, we explore whether effects of cryptogams on belowground microbes can facilitate progressive shifts in sand dune succession. •We linked aboveground vegetation, belowground bacterial and fungal communities, and soil chemical properties in six successional stages in Arctic inland sand dunes: bare sand, grass, moss, lichen, ericoid heath and mountain birch forest. •Compared to the bare sand and grass stages, microbial biomass and the proportion of fungi increased in the moss stage, and later stage microbial groups a…
Extinction risk under coloured environmental noise
2000
Positively autocorrelated red environmental noise is characterized by a strong dependence of expected sample variance on sample length. This dependence has to be taken into account when assessing extinction risk under red and white uncorrelated environmental noise. To facilitate a comparison between red and white noise, their expected variances can be scaled to be equal, but only at a chosen time scale. We show with a simple one-dimensional population dynamics model that the different but equally reasonable choices of the time scale yield qualitatively different results on the dependence of extinction risk on the colour of environmental noise: extinction risk might increase as well as decre…
Visible implant elastomer (VIE) success in early larval stages of a tropical amphibian species
2020
AbstractAnimals are often difficult to distinguish at an individual level, but being able to identify individuals can be crucial in ecological or behavioral studies. In response to this challenge, biologists have developed a range of marking (tattoos, brands, toe-clips) and tagging (PIT, VIA, VIE) methods to identify individuals and cohorts. Animals with complex life cycles are notoriously hard to mark because of the distortion or loss of the tag across metamorphosis. In frogs, few studies have attempted larval tagging and none have been conducted on a tropical species. Here, we present the first successful account of VIE tagging in early larval stages (Gosner stage 25) of the dyeing poison…
Environment-sensitivity functions for gross primary productivity in light use efficiency models
2022
International audience; The sensitivity of photosynthesis to environmental changes is essential for understanding carbon cycle responses to global climate change and for the development of modeling approaches that explains its spatial and temporal variability. We collected a large variety of published sensitivity functions of gross primary productivity (GPP) to different forcing variables to assess the response of GPP to environmental factors. These include the responses of GPP to temperature; vapor pressure deficit, some of which include the response to atmospheric CO2 concentrations; soil water availability (W); light intensity; and cloudiness. These functions were combined in a full fact…
Alder pollen in Finland ripens after a short exposure to warm days in early spring, showing biennial variation in the onset of pollen ripening
2017
Abstract We developed a temperature sum model to predict the daily pollen release of alder, based on pollen data collected with pollen traps at seven locations in Finland over the years 2000–2014. We estimated the model parameters by minimizing the sum of squared errors (SSE) of the model, with weights that put more weight on binary recognition of daily presence or absence of pollen. The model results suggest that alder pollen ripens after a couple of warm days in February, while the whole pollen release period typically takes up to 4 weeks. We tested the model residuals against air humidity, precipitation and wind speed, but adding these meteorological features did not improve the model pr…
Impact of plant cover on the cavity-nesting antTemnothorax crassispinus
2017
1. Plant communities influence the availability of important resources for ants, such as nest sites and food, as well as environmental conditions. Thus, plants affect the abundance and distribution of ants. 2. In a field experiment, the influence of plant cover on the settlement of nest sites and per-capita productivity of sexual individuals by the ant Temnothorax crassispinus was analysed. In July 2014, in five areas with patches of alien balsam Impatiens parviflora, and another five of native balsam I. noli-tangere, transects composed of artificial nests were established; the nest sites were situated inside patches of balsams, and outside of them. Four hundred and forty artificial nests w…
The Bias of combining variables on fish's aggressive behavior studies.
2019
Made available in DSpace on 2019-10-06T16:27:42Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-07-01 Quantifying animal aggressive behavior by behavioral units, either displays or attacks, is a common practice in animal behavior studies. However, this practice can generate a bias in data analysis, especially when the variables have different temporal patterns. This study aims to use Bayesian Hierarchical Linear Models (B-HLMs) to analyze the feasibility of pooling the aggressive behavior variables of four cichlids species. Additionally, this paper discusses the feasibility of combining variables by examining the usage of different sample sizes and family distributions to aggressive …