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Site fidelity is driven by predictable resource distributions in time and space. However, intrinsic factors related to an individual’s physiology and life-history traits can contribute to consistent foraging behaviour and movement patterns. Using 11 yr of continuous geolocation tracking data (fall 2008 to spring 2019), we investigated spatiotemporal consistency in non-breeding movements in a pelagic seabird population of black-legged kittiwakes Rissa tridactyla breeding in the High Arctic (Svalbard). Our objective was to assess the relative importance of spatial versus temporal repeatability behind inter-annual movement consistency during winter. Most kittiwakes used pelagic regions of the western North Atlantic. Winter site fidelity was high both within and across individuals and at meso (100-1000 km) and macro scales (>1000 km). Spatial consistency in non-breeding movement was higher within than among individuals, suggesting that site fidelity might emerge from individuals’ memory to return to locations with predictable resource availability. Consistency was also stronger in space than in time, suggesting that it was driven by consistent resource pulses that may vary in time more so than in space. Nonetheless, some individuals displayed more flexibility by adopting a strategy of itinerancy during winter, and the causes of this flexibility are unclear. Specialization for key wintering areas can indicate vulnerability to environmental perturbations, with winter survival and carry-over effects arising from winter conditions as potential drivers of population dynamics. : Spatial distribution · Individual consistency · Migration · Repeatability · Nearest neighbor distance · Biologging · Global Location Sensors · GLS

Single molecule localization microscopy (SMLM) provided an unprecedented insight into the sub-nuclear organization of proteins and nucleic acids but apart from the nuclear envelope the role of the nuclear lipids in the functional organization of the cell nucleus was less studied. Nevertheless, nuclear lipids and specifically phosphatidylinositol phosphates (PIPs) play increasingly evident roles in gene expression. Therefore, here we provide the SMLM-based approach for the quantitative evaluation of the nuclear PIPs distribution while preserving the context of nuclear architecture. Specifically, on the example of phosphatidylinositol 4,5-bisphosphate (PIP2) we have: • Implemented and optimized the dual-color dSTORM imaging of nuclear PIP2. • Customized the Nearest Neighbor Distance analysis using ImageJ2 plug-in ThunderSTORM to quantitatively evaluate the spatial distribution of nuclear PIP2. • Developed an ImageJ2 tool for the visualization of the Nearest Neighbor Distance analysis results in cellulo. Our customization of the dual-color dSTORM imaging and quantitative analysis provide a tool that is independent of but complementary to the biochemical and lipidomic analyses of the nuclear PIPs. Contrary to the biochemical and lipidomic analyses, the advantage of our analysis is that it preserves the spatial context of the nuclear PIP distribution.

Spatial patterns can reveal a lot about ecological processes, but our knowledge of the spatial ecology of tree regeneration at a fine scale is quite limited. Therefore, we studied the spatial patterns of living and dead small trees in two subalpine Norway spruce forest reserves in Switzerland (Scatlè and Bödmerenwald) using three types of analyses. First, we investigated the distances of small trees to the nearest large neighboring tree and, by using maximum distances as indicator, inferred the size of forest gaps, detecting mainly forest gaps of small size, although with two exceptions that were driven by large-scale disturbances. Second, we accounted for spatial inhomogeneity in the pattern of small and large trees (i.e., variations in local tree densities) by including environmental covariates in point pattern models. Latitude (within the forest reserve), elevation and aspect contributed significantly to explaining the density of living and dead small trees, and partly of living and dead large trees. Yet, the influence of these environmental covariates varied between the two reserves due to their different topography and peculiar site conditions. Third, we analyzed neighborhood interactions between small and large trees based on the vicinity and size of trees. In both forest reserves, small living trees were randomly dispersed around large dead trees over a broad range of distances and, at certain distances in one reserve, even dispersed away from them. Small living trees further showed clustering around large living trees at short distances and dispersion at large distances. Small dead trees featured mainly a random pattern, although with a tendency to cluster around large neighbors at short distances, irrespective whether these were living or dead. Yet, the weakening of clustering with increasing distances indicates that the influence of large trees on small trees varies with spatial scale and thus that these neighborhood interactions are scale-dependent. Overall, our study contributes to a better understanding of the spatial ecology of mortality in small trees and ultimately of tree regeneration processes and stand dynamics in mountain forests., Forest Ecology and Management, 494, ISSN:0378-1127, ISSN:1872-7042

Since the entropy is a popular randomness measure, there are many studies for the estimation of entropies for given random samples. In this paper, we propose an estimation method of the R&eacute, nyi entropy of order &alpha, Since the R&eacute, is a generalized entropy measure including the Shannon entropy as a special case, the proposed estimation method for R&eacute, nyi entropy can detect any significant deviation of an ergodic stationary random source&rsquo, s output. It is shown that the expected test value of the proposed scheme is equivalent to the R&eacute, After deriving a general representation of parameters of the proposed estimator, we discuss on the particular orders of R&eacute, nyi entropy such as &alpha, &rarr, 1 , &alpha, = 1 / 2 , and &alpha, = 2 . Because the R&eacute, nyi entropy of order 2 is the most popular one, we present an iterative estimation method for the application with stringent resource restrictions.

The introduction of alien species could be changing food source composition, ultimately restructuring demography and spatial distribution of native communities. In Argentine Patagonia, the exotic European hare has one of the highest numbers recorded worldwide and is now a widely consumed prey for many predators. We examine the potential relationship between abundance of this relatively new prey and the abundance and breeding spacing of one of its main consumers, the Black-chested Buzzard-Eagle (Geranoaetus melanoleucus). First we analyze the abundance of individuals of a raptor guild in relation to hare abundance through a correspondence analysis. We then estimated the Nearest Neighbor Distance (NND) of the Black-chested Buzzard-eagle abundances in the two areas with high hare abundances. Finally, we performed a metaregression between the NND and the body masses of Accipitridae raptors, to evaluate if Black-chested Buzzard-eagle NND deviates from the expected according to their mass. We found that eagle abundance was highly associated with hare abundance, more than with any other raptor species in the study area. Their NND deviates from the value expected, which was significantly lower than expected for a raptor species of this size in two areas with high hare abundance. Our results support the hypothesis that high local abundance of prey leads to a reduction of the breeding spacing of its main predator, which could potentially alter other interspecific interactions, and thus the entire community.

cited By 0; International audience; Here we report a novel technology to obtain arrays of highly efficient magnetic micro-traps that relies on simple fabrication process. Developed micro-traps consist in chains of iron particles diluted in polydimethylsiloxane (PDMS). We analyzed the microstructure of the composite membrane by X-ray tomography. It revealed the predominance of aligned chain-like agglomerates. Largest traps, with diameter ranging from 4 to 11 µm, are found to be the most efficient. The trap arrays were characterized by a density of 1300 magnetic micro-traps/mm2, an average nearest neighbor distance of 21 µm. Implemented in a microfluidic channel operating at a relatively high flow rate of 0.97 µL/s—a flow velocity of 8.3 mm/s—we measured a trapping efficiency of more than 99.7%, with a throughput of up to 7100 trapped beads/min. These performances are competitive with other approaches like hydrodynamic trapping. The strengths of this technology are its simple fabrication and easy handling.