Spatial behaviour of a female raccoon (Procyon lotor) at the edge of the species’ European distribution range

A female raccoon was radio-tracked in Luxembourg, at the edge of the species distribution range in Europe, from April 2004 to June 2004. The 100% minimum convex polygon home range size of 340 ha was smaller than home ranges reported from the core of the species European distribution range in Lower Saxony, Germany. The animal mostly used Norway spruce as resting sites and appeared to exhibit no site fidelity.     

Changes in the area of optimal tree cover of a declining Afro-Palaearctic migrant across the species’ wintering range

Land use change in sub-Saharan Africa continues apace, but its role in driving the declines of Afro-Palaearctic migrant birds is unknown. This is due partly to a lack of knowledge of migrants’ requirements on the wintering grounds, and of spatially explicit assessments of land cover change. We compared tree cover data derived from satellite remote sensing (available for the period 2000–2014) with distributional data from surveys in four West African countries for the Wood Warbler Phylloscopus sibilatrix, one such declining migrant, to determine the extent of, and change in, optimal tree cover. Wood Warblers were most likely to occur where tree cover per hectare was between 40 and 61% (optimal tree cover). Extrapolation to the whole of the wintering range indicated there was a 46.7% net increase in extent between 2000 and 2014. This was due to an alarming 27 683 km² of previously closed forest being degraded from > 61% cover to between 40 and 61%, an area greater than that of the optimal tree cover that was lost. Increases in optimal tree cover were greatest in countries with greatest forest cover, such as Sierra Leone, Liberia, Côte d'Ivoire and Democratic Republic of Congo. The results suggest that loss of optimal tree cover in the wintering range might not be a key driver of population decline for Wood Warblers, but the degradation will probably impact species that rely upon dense tree cover.     

What factors shape female phenotypes of a poleward‐moving damselfly at the edge of its range?

Individuals at the expansion front during a climate‐driven range expansion are expected to differ phenotypically from those individuals in core populations. Little information is known about the joint, potentially opposing, effects of stressful conditions at the range edge versus evolutionary changes that take place during range expansion in shaping the phenotypes at the range front. We investigated the effect of range expansion on immune function, body condition and flight‐related morphology (flight muscle ratio, wing loading, and wing aspect ratio) of field‐collected females of the poleward‐moving damselfly Coenagrion scitulum. Individuals at the expansion front had a lower body condition, which indicated more stressful conditions at the range edge. Despite the counteracting effect of the shorter growth season, the higher flight muscle ratios at the expansion front indicated a strong selection for dispersal ability during range expansion. The current study suggests that models need to incorporate the interplay of stressful conditions and evolutionary processes at the expansion front to arrive at robust predictions of future species distributions under global warming. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 112 , 556–568.     

Variations in flocking behaviour from core to peripheral regions of a bird species’ distribution range

Flocking behaviour in birds reflects the outcome of a momentary trade-off between increased foraging efficiency and improved predator avoidance. However, these changing patterns remain poorly known at any spatial or temporal scale. The aim of the present study was first to investigate seasonal fluctuations of flocking behaviour throughout the entire distribution range of a species and secondly to explore behavioural responses to daily temperature variations. From 2000 to 2010, sightings of Peruvian Thick-knees (Burhinus superciliaris) were collected throughout Ecuador, Peru and Chile. There were strong differences in flocking behaviour between Chilean and Peruvian populations. While Thick-knees occurred into few large year-round flocks in Chile, flock occurrence was highly seasonal in Peru, where group size grew gradually from loose flocks at the end of the breeding season to a few large ones by the middle of the year. Time of day seemed not to affect the species detectability but was negatively related to flock size. Variations in the flocking behaviour of Peruvian Thick-knees throughout its distribution range suggest that aggregation patterns might indicate individuals responding to seasonally fluctuating ecological pressures, such as those derived from predation, foraging or climate.     

What shapes the range edge of a dominant African savanna tree,Colophospermum mopane? A demographic approach

Climate is widely assumed to be the primary process that limits the distribution ranges of plants. Yet, savannas have vegetation not at equilibrium with climate, instead its structure and function are shaped by interactions between fire, herbivory, climate, and vegetation. I use the rich literature of a dominant African savanna woody plant, Colophospermum mopane, to demonstrate that climate and disturbance interact with each demographic stage to shape this species range limits. This synthesis highlights that climate‐based predictions for the range of C. mopane inadequately represents the processes that shape its distribution. Instead, seed bank depletion and rainfall limitation create a demographic bottleneck at the early seedling stage. The legacy of top‐kill from disturbance changes tree stand architecture causing a critical limitation in seed supply. Exposure to top‐kill at all demographic stages causes a vigorous resprouting response and shifts tree architecture from that of 1–2 stemmed tall trees to that of a short multi‐stemmed shrub. The shorter, multi‐stemmed shrubs are below the height threshold (4 m) at which they can produce seeds, resulting in shrub‐dominated landscapes that are effectively sterile. This effect is likely most pronounced at the range edge where top‐kill‐inducing disturbances increase in frequency. The proposed mechanistic, demographic‐based understanding of C. mopane''s range limits highlights the complexity of processes that interact to shape its range edges. This insight serves as a conceptual model for understanding the determinants of range limits of other dominant woody savannas species living in disturbance limited ecosystems.     

Deleterious mutations in a hybrid zone: can mutational load decrease the barrier to gene flow?

The aim of this paper is to investigate the effect of deleterious mutations in a hybrid zone maintained by selection against hybrids. In such zones, linkage disequilibria among hybrid depression loci, resulting from a balance between migration and selection, are crucial in maintaining the barrier because they allow each locus, in addition to its own selection coefficient, to cumulate indirect selective effects from other loci. Deleterious alleles produce heterosis and increase by this means the effective migration rate in structured populations. In a hybrid zone, they therefore contribute to decrease linkage disequilibria as well as the barrier to gene flow imposed by hybrid depression. However, deleterious mutations have no effect: (i) when selection against hybrids is weak, because linkage disequilibria are small even without heterosis in this case, or (ii) when selection against hybrids is so strong that it overwhelms heterosis. On the other hand, with moderate selection against hybrids, the decrease in the strength of the barrier due to heterosis may reach detectable levels, although it requires relatively small population sizes and/or migration rates. The effect is expected to be small and only within small genomes where loci are tightly linked can it become strong. Nevertheless, neglecting mutational load may to some extent obscure the estimations of selective parameters based either on artificial F1 crosses or on cline characteristics.     

Golgi’s way: a long path toward the new paradigm of the intra-Golgi transport

The transport of proteins and lipids is one of the main cellular functions. The vesicular model, compartment (or cisterna) maturation model, and the diffusion model compete with each other for the right to be the paradigm within the field of the intra-Golgi transport. These models have significant difficulties explaining the existing experimental data. Recently, we proposed the kiss-and-run (KAR) model of intra-Golgi transport (Mironov and Beznoussenko in Int J Mol Sci 13(6):6800–6819, 2012), which can be symmetric, when fusion and fission occur in the same location, and asymmetric, when fusion and fission take place at different sites. Here, we compare the ability of main models of the intra-Golgi transport to explain the existing results examining the evidence in favor and against each model. We propose that the KAR model has the highest potential for the explanation of the majority of experimental observations existing within the field of intracellular transport.     

Spatial heterogeneity of the species composition of a clavarioid fungi’s compex in the Eurasian Arctic

Using the example of a model group of macromycete (clavarioid fungi), a large-scale investigation into the mycological complex of the Eurasian Arctic is conducted. The species composition of clavarioid fungi’s complex is revealed in all longitudinal sectors and latitudinal subzones, and a comparative analysis is carried out. It has been determined that, among groups of aphyllophoroid fungi, the clavarioid life form is the most adapted to the extremally psychrophilic conditions of the Arctic. It is shown that the near-oceanic sectors are the richest, whereas the continental sectors are much poorer. The distribution of the species composition of fungi conforms to the similar distribution of flowering plants, especially hemicryptophytes. The average annual quantity of atmospheric precipitation is the leading climatic factor. The differences make it possible to subdivide the Eurasian Arctic into four mycogeographical regions: Atlantic (European), Siberian, Chukotian (Beringian), and High Arctic.     

Variation in the reproductive performance of the Trollius–Chiastocheta mutualism at the edge of its range in north-east Germany

Empirical studies into obligate pollination mutualisms which elucidate the variation in reproductive performance of shrinking populations within human-altered environments are rare. This study focuses on the obligate pollination mutualism between Trollius europaeus (Ranunculaceae) and fly species of the genus Chiastocheta which act both as the plant’s main pollinators and as predators in that their larvae eat a fraction of the developing seeds. The study area is situated in the lowlands of north-east Germany. Many populations of T. europaeus have become comparatively small and scattered in this region as a consequence of agricultural land use intensification. We studied the plant’s reproductive fitness in populations ranging in size from 7 to 12,000 flowers. In a field experiment, we applied four pollination treatments and also recorded fly density in 28 natural T. europaeus populations. The fitness of the offspring from 19 populations was studied in a common garden experiment. In both approaches, a reduction in the fitness of small host plant populations could be demonstrated. Fitness loss can be put down to the quantitative and qualitative limitation of pollen caused by inbreeding and the negative feedback on relative seed set caused by the reduced ability of small plant populations to support a sufficiently large fly population. Although increases in fly density are associated with rising predation costs, the plant species’ net benefit is a positive function of its population size. Our study highlights the reproductive variability of the Trollius–Chiastocheta interaction along a population size gradient in a marginal region of its range, thus contributing to the understanding of the overall variability of this mutualism.     

Is the originality of a species measurable?

In this paper, we introduce the concept of 'originality of a species within a set' in order to indicate the average rarity of all the features belonging to this species. Using a phylogenetic tree of 70 species of New World terrestrial Carnivora, we suggest measuring the originality by a probability distribution. This maximizes the expected number of features shared by two species randomly drawn from the set. By using this new index, we take account of branch lengths whereas current indices of originality focus on tree topology. As a supplement to Nee and May's optimizing algorithm, we find that originality must be one of the criteria used in conservation planning.     

Does a facultative mutualism limit species range expansion?

The availability and quality of mutualists beyond a species’ range edge may limit range expansion. With the legume Chamaecrista fasciculata, we asked to what extent the availability and quality of rhizobia beyond the range edge limits host range expansion. We tested the effect of rhizobia availability on plant growth by transplanting seed from three locations into five sites spanning C. fasciculata’s range (interior, at the northern and western range edges, and beyond the range edges), and inoculating half the seeds with rhizobia. We recorded growth of all surviving plants, and, for the uninoculated plants, whether they had formed nodules or not. We isolated rhizobia from nodules collected on the uninoculated plants, and cross-inoculated seed from four populations (both range edge and interior populations) in the greenhouse to determine whether the quality of rhizobia differed between regions. We found that seeds transplanted beyond the range edge were less likely to be nodulated when they were not experimentally inoculated, and there was benefit to inoculation at all sites. In the greenhouse, the three inocula that formed nodules on plants, from the range interior, northern edge and beyond the northern edge, did not detectably differ in their effect on plant growth. These results suggest that low densities of suitable rhizobia beyond the range edge may limit range expansion of legume species.     

Protamine increases the affinity of 3′-phosphoadenosine 5′-phosphosulfate toward a sulfotransferase from chicken embryo epiphyseal cartilage

A 3′-phosphoadenosine 5′-phosphosulfate (PAPS):chondroitin sulfate sulfotransferase from chicken embryo epiphyseal cartilage, which was partially purified, exhibited a molecular mass of 150 kDa. The enzymatic sulfation of totally desulfated chondroitin was activated up to 12-fold by protamine while the sulfation of partially sulfated chondroitin was activated only 3-fold. Protamine increased the affinity of the enzyme for PAPS about 4-fold when partially desulfated chondroitin was used as sulfate acceptor. The S_0.5 for the totally desulfated chondroitin was not affected by protamine, while high PAPS concentration slightly increased the affinity of the enzyme for the same sulfate acceptor. The possible role of these substances in the regulation of the sulfation of chondroitin sulfate is discussed.     

Okasha’s evolution and the levels of selection: toward a broader conception of theoretical biology

The debate about the levels of selection has been one of the most controversial both in evolutionary biology and in philosophy of science. Okasha’s book makes the sort of contribution that simply will not be able to be ignored by anyone interested in this field for many years to come. However, my interest here is in highlighting some examples of how Okasha goes about discussing his material to suggest that his book is part of an increasingly interesting trend that sees scientists and philosophers coming together to build a broadened concept of “theory” through a combination of standard mathematical treatments and conceptual analyses. Given the often contentious history of the relationship between philosophy and science, such trend cannot but be welcome.