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Our study investigates how factors, such as latitude, productivity, and several environmental variables, influence contemporary patterns of the species richness in North American turtles. In particular, we test several hypotheses explaining broad-scale species richness patterns on several species richness data sets: ( i) total turtles, ( ii) freshwater turtles only, ( iii) aquatic turtles, ( iv) terrestrial turtles only, ( v) Emydidae, and ( vi) Kinosternidae. In addition to spatial data, we used a combination of 25 abiotic variables in spatial regression models to predict species richness patterns. Our results provide support for multiple hypotheses related to broad-scale patterns of species richness, and in particular, hypotheses related to climate, productivity, water availability, topography, and latitude. In general, species richness patterns were positively associated with temperature, precipitation, diversity of streams, coefficient of variation of elevation, and net primary productivity. We also found that North America turtles follow the general latitudinal diversity gradient pattern (i.e., increasing species richness towards equator) by exhibiting a negative association with latitude. Because of the incongruent results among our six data sets, our study highlights the importance of considering phylogenetic constraints and guilds when interpreting species richness patterns, especially for taxonomic groups that occupy a myriad of habitats. [ABSTRACT FROM AUTHOR]

Duff fires (smouldering in fermentation and humus forest floor horizons) and their consequences have been documented in fire-excluded ecosystems but with little attention to their underlying drivers. Duff characteristics influence the ignition and spread of smouldering fires, and their spatial patterns on the forest floor may be an important link to the heterogeneity of consumption observed following fires. We evaluated fuel bed characteristics (depths, bulk densities, and moisture) of duff in a long-unburned longleaf pine ( Pinus palustris Mill.) forest and corresponding spatial variation across 100 to 103 m scales. Fermentation and humus horizon depths both varied (∼100% coefficient of variation) but with moderate to strong spatial autocorrelation at fine scales. Fermentation bulk density varied less than humus bulk density, which varied considerably at fine scales. Fermentation horizons held more moisture (average 49%-172%) and were much more variable than humus following rainfall, which remained stable and relatively dry (average 28%-62%). Humus moisture was moderately autocorrelated at fine scales, but fermentation moisture was highly variable, showing no evidence of spatial autocorrelation under dry, intermediate, or wet conditions. Observations from this study highlight the underlying spatial variability in duff, informing future sampling and fire management efforts in these long-unburned coniferous forests. [ABSTRACT FROM AUTHOR]

Characterization of the seasonal and inter-annual spatial and temporal variability of rainfall in a changing climate is vital to assess climate-induced changes and suggest adequate future water resources management strategies. Trends in annual, seasonal and maximum 30-day extreme rainfall over Ethiopia are investigated using 0.5° latitude × 0.5° longitude gridded monthly precipitation data. The spatial coherence of annual rainfall among contiguous rainfall grid points is also assessed for possible spatial similarity across the country. The correlation between temporally coinciding North Atlantic Multidecadal Oscillation (AMO) index and annual rainfall variability is examined to understand the underlying coherence. In total 381 precipitation grid points covering the whole of Ethiopia with five decades (1951–2000) of precipitation data are analysed using the Mann-Kendall test and Moran spatial autocorrelation method. Summer (July–September) seasonal and annual rainfall data exhibit significant decreasing trends in northern, northwestern and western parts of the country, whereas a few grid points in eastern areas show increasing annual rainfall trends. Most other parts of the country exhibit statistically insignificant trends. Regions with high annual and seasonal rainfall distribution exhibit high temporal and spatial correlation indices. Finally, the country is sub-divided into four zones based on annual rainfall similarity. The association of the AMO index with annual rainfall is modestly good for northern and northeastern parts of the country; however, it is weak over the southern region. Editor Z.W. Kundzewicz; Associate editor S. Uhlenbrook Citation Wagesho, N., Goel, N.K., and Jain, M.K. 2013. Temporal and spatial variability of annual and seasonal rainfall over Ethiopia. Hydrological Sciences Journal, 58 (2), 354–373. [ABSTRACT FROM AUTHOR]

One of the major issues when applying truck destination choice models with a large number of alternatives is how to sample a set of non-chosen traffic analysis zones (TAZs) to construct a destination choice set. Despite the large number of studies applying various sampling strategies, the question remains as to what are optimal strategies in model development. This study examined how the sampling strategies affect the performances of truck destination choice models. Two sampling methods (simple random sampling and stratified importance sampling) and four different sample sizes were tested using the truck trip data of Korea. For stratified importance sampling, Moran's I statistics were used to divide the entire study area into multiple strata, and Neyman allocation was used to determine the appropriate number of samples for each stratum. The truck trip productions were distributed by a Monte Carlo simulation, and two measurements of effectiveness (MOEs), average trip length (ATL) and trip length distribution (TLD), were used to evaluate and compare the performance of the destination choice models with respect to the sampling strategy. The results showed that the models using stratified importance sampling with smaller sample sizes performed better than others. [ABSTRACT FROM AUTHOR]

Population genetics has fueled a substantial growth in studies of dispersal, a life-history trait that has important applications in ecology and evolution. Mammals typically exhibit male-biased gene flow, so this pattern often serves as a null hypothesis in empirical studies. Estimation of dispersal using population genetics is not without biases, so we utilized a combination of population genetic methods and simulations to evaluate gene flow within the American badger ( Taxidea taxus (Schreber, 1777)), a highly elusive and poorly understood mustelid. A total of 132 badgers captured between 2001 and 2002 were genotyped at nine microsatellite loci to investigate fine-scale genetic structure consistent with philopatry in females and dispersal in males. Resultant genetic patterns were largely consistent with a panmictic population with little evidence for sex-biased dispersal, and simulations confirmed that our sampling scheme did not substantially impact our statistics. An overall deficiency of heterozygotes was observed across the Lower Peninsula, which indicates either a Wahlund effect, mixing of separate populations, or inbreeding. Our study emphasizes the importance in deciphering between actual behavioral mechanisms and sampling effects when interpreting genetic data to understand other factors that influence dispersal like population density and territoriality. [ABSTRACT FROM AUTHOR]

There is a crucial need to understand the genetic consequences of landscape modifications on continuous populations that could become fragmented, and to evaluate the degree of differentiation of isolated populations that were historically part of the core. Using 15 microsatellite loci, we evaluated the genetic structure of American black bears ( Ursus americanus Pallas, 1780) across a vast, contiguous Ontario landscape (>1 × 106 km2) that largely represents their pre-European settlement distribution. Because geographic barriers are absent, we predicted that isolation by distance would drive genetic structure. We identified three genetic clusters (Northwest, Southeast, and Bruce Peninsula) that were less differentiated than when assessed with mtDNA, suggesting the influence of male-biased dispersal on large-scale genetic differentiation. Isolation by distance ( r = 0.552, P = 0.001) was supported by a weak, clinal variation between Northwest and Southeast, illustrating the challenges to delineate populations in wide-ranging taxa. The Bruce Peninsula cluster, confined to a small area under strong anthropogenic pressures, was more differentiated from neighbouring clusters ( FST > 0.13, P < 0.0001), with a genetic diversity corresponding to disjunct populations of black bears. Our results could be used in landscape genetics models to project the evolution of population differentiation based on upcoming landscape modifications in northern regions of North America. [ABSTRACT FROM AUTHOR]

The spatial distribution of pair quality within waterbird colonies has been suggested to follow one of three theoretical models: central-periphery, satellite, or random. The central-periphery pattern occurs in homogeneous habitats, where good-quality pairs occupy better protected, central nesting sites. In contrast, the satellite and random patterns are associated with heterogeneous habitats and they assume that good-quality pairs occupy the most attractive nesting sites irrespectively of their location within the colony. Spatial patterns of laying date, clutch size, and fledging success were analysed with geostatistical tools in the colony of tree-nesting subspecies of Great Cormorant ( Phalacrocorax carbo sinensis (Blumenbach, 1798)) in central Poland. There was support for the random or satellite model in the distribution of clutch size, which was considered a reliable proxy of pair quality. We also found a positive correlation of clutch size with nest height. These results implicate that the habitat of tree-nesting colonial waterbirds may produce sufficient variation in the nesting-site quality to disrupt the central-periphery gradients of pair-quality distribution. In contrast, distribution of fledging success within the colony followed a clear central-periphery pattern, which was suggested to reflect an increased predation rate at the edges of the colony, rather than the intrinsic quality of breeding birds. [ABSTRACT FROM AUTHOR]

The colour morphs of immature female cones in European larch (Larix decidua Mill.) and Norway spruce (Picea abies (L.) Karst.) are green, red, and intermediate in colour. For the first time, these three colour morphs were studied to verify the thermoregulatory hypothesis and to investigate its underlying genetic spatial pattern. The study was based on an extensive systematic sampling, and data were analysed using principal component analysis (PCA), binary logistic regression (BLR), and spatial autocorrelation. Correlations between the nontransformed environmental variables and PC scores revealed two main ecological gradients, (i) altitude–temperate and (ii) annual precipitation. Loadings of the first two principal components exceeded 85% in both species. BLR was used to test the effect of the altitude–temperature gradient on the probability of occurrence of a specific cone colour. In both species, the occurrence of red cones was significantly positively related to high altitude with low temperatures, while green cones were significantly negatively correlated with decreasing temperature and increasing altitude. In both species the spatial pattern based on a putative Mendelian gene was nonrandom as indicated by significantly high Moran’s I values based on altitudinal distance. Spatial genetic structure was probably maintained by limited gene flow and balanced selection that maintained short-distance genetic differentiation. [ABSTRACT FROM AUTHOR]

Many of Wisconsin's jack pine forests originated following fire or agricultural abandonment creating a forest mosaic fragmented by a history of disturbance and past land use. The extent and patterning of genetic diversity at a landscape scale (30 × 30 km) was investigated in 82 natural Pinus banksiana Lamb. (jack pine) stands in Wisconsin using 14 polymorphic allozymes. Most measures of genetic diversity and overall allelic frequencies varied little among these stands, and Reynolds' (coancestry) genetic distances were small (mean = 0.026). Genetic differentiation among stands was limited but significant ([sub ST] = 0.022). Gene flow (Nm) is extensive, estimated to be slightly more than 11 migrants per generation. Autocorrelation analysis provided evidence for a weak pattern of genetic structure at a few loci with a spatial scale of 8–15 km. However, when all loci were examined together the populations did not present a clear spatial pattern across the landscape, probably because of extensive gene flow among stands.Key words: jack pine, allozymes, genetic diversity, population differentiation, spatial autocorrelation, gene flow.Plusieurs des forêts de pin gris du Wisconsin proviennent d'incendies ou de l'abandon de l'agriculture créant ainsi une forêt en mosaïque, fragmentée par l'histoire des perturbation et l'utilisation passée du territoire. Les auteurs ont étudié l'étendue et les patrons de diversité génétique, à l'échelle du paysage (30 × 30 km) dans 82 stations naturelles du Pinus banksiana Lamb. (pin gris) au Wisconsin, en utilisant 14 allozymes polymorphiques. La plupart des mesures de diversité génétique et l'ensemble des fréquences alléliques varient peu entre ces stations, et les distances génétiques de Reynold (ancêtres communs) sont faibles (0,026 en moyenne). La différentiation génétique entre peuplements est limitée mais significative ([sub ST] = 0,022). Le flux de gènes (Nm) est extensif : on l'estime à un peu plus de 11 migrants par génération. L'analyse d'autocorrélation supporte l'idée d'un faible patron de structure génétique sur quelques loci, à une échelle spatiale de 8 à 15 km. Cependant, lorsqu'on examine tous les loci ensemble, les populations ne présentent pas de patron spatial défini pour l'ensemble du paysage, probablement dû à un flux extensif de gènes entre les stations.Mots clés : pin gris, allozymes, diversité génétique, différentiation des populations, autocorrélation spatiale, flux de gènes.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]