Are Antarctic suspension-feeding communities different from those elsewhere in the world?

This paper reviews the trophic ecology of benthic suspension feeders in Antarctic shelf communities, studied within SCAR's EASIZ Programme, in comparison with published information from other seas. Dense benthic suspension-feeder communities capture large quantities of particles and may directly regulate primary, and indirectly, secondary production in littoral food chains. Most work has been performed in temperate and tropical seas; however, little is known about suspension feeders in cold environments. Recent studies on Antarctic littoral benthic suspension feeders suggest the period of winter inactivity may last only a few weeks. This contrasts with the hypothesis that in Antarctic communities there is a prolonged period of minimal activity lasting at least 6 months during the austral winter. Results from other oceans may explain how dense benthic communities could develop under such conditions. Alternative food sources, i.e. the "fine fraction", sediment resuspension, lateral advection and efficient food assimilation may play a significant role in the development of suspension-feeder dominated, very diversified, high biomass and three-dimensionally structured communities on the Antarctic shelf.     

Distinguishing foldable proteins from nonfolders: When and how do they differ?

When a denatured polypeptide is put into refolding conditions, it undergoes conformational changes on a variety of times scales. We set out here to distinguish the fast events that promote productive folding from other processes that may be generic to any non-folding polypeptide. We have apply an ab initio folding algorithm to model the folding of various proteins and their compositionally identical, random-sequence analogues. In the earliest stages, proteins and their scrambled-sequence counterparts undergo indistinguishable reductions in the extent to which they explore conformation space. For both polypeptides, an early contraction occurs but does not involve the formation of a distinct intermediate. Following this phase, however, the naturally-occurring sequences are distinguished by an increase in the formation of three-body correlations wherein a hydrophobic group desolvates and protects an intra-molecular hydrogen bond. These correlations are manifested in a mild but measurable reduction of the accessible configuration space beyond that of the random-sequence peptides, and portend the folding to the native structure. Hence, early events reflect a generic response of the denatured ensemble to a change in solvent condition, but the wild-type sequence develops additional correlations as its structure evolves that can reveal the protein's foldability.     

Zebra mussels in Italy: where do they come from?

The zebra mussel Dreissena polymorpha is widely present in Italy, but Italian populations of this bivalve have never been genetically characterized. The mitochondrial Cytochrome Oxidase subunit I gene fragments have been used to determine the genetic structures of 3 populations from Lake Garda (n = 30), the first Italian basin colonized by this species, as well as 2 populations from Lake Constance, Germany (n = 14). A Neighbor-Joining tree and a Maximum Likelihood analysis were performed with 4 new Italian (LG1-LG4) and 3 German (LC1-LC3) haplotypes, also considering all the available Dreissena sequences from GenBank in order to estimate phylogeographic relationships. Almost all Italian haplotypes clustered with German and mid-European samples providing evidences of a mixed origin for Italian mussels. We speculate about Lake Garda colonization, for which the hypothesized "German origin" has been partially confirmed as well as the necessity of more efficient control strategies at least to minimize new colonizations.     

Category differences in brain activation studies: where do they come from?

Differences in the neural processing of six categories of pictorial stimuli (maps, body parts, objects, animals, famous faces and colours) were investigated using positron emission tomography. Stimuli were presented either with or without the written name of the picture, thereby creating a naming condition and a reading condition. As predicted, naming increased the demands on lexical processes. This was demonstrated by activation of the left temporal lobe in a posterior region associated with name retrieval in several previous studies. This lexical effect was common to all meaningful stimuli and no category-specific effects were observed for naming relative to reading. Nevertheless, category differences were found when naming and reading were considered together. Stimuli with greater visual complexity (animals, faces and maps) enhanced activation in the left extrastriate cortex. Furthermore, map recognition, which requires greater spatio-topographical processing, also activated the right occipito-parietal and parahippocampal cortices. These effects in the visuo-spatial regions emphasize inevitable differences in the perceptual properties of pictorial stimuli. In the semantic temporal regions, famous faces and objects enhanced activation in the left antero-lateral and postero-lateral cortices, respectively. In addition, we showed that the same posterior left temporal region is also activated by body parts. We conclude that category-specific brain activations depend more on differential processing at the perceptual and semantic levels rather than at the lexical retrieval level.     

Host specificity in ectomycorrhizal communities: what do the exceptions tell us?

Classic ectomycorrhizal symbioses are mutualisms that involvethe exchange of fixed carbon for mineral nutrients between plantroots and fungi. They are unique in the way they contain featuresof both intimate and diffuse symbioses. The degree of host specificityvaries, particularly among the fungi. Here we examine two exceptionalcases of specificity to see what they tell us about the advantagesof specificity, how it is initiated, and the potential rolethat it plays in complex ecosystems. The first case involvesnon-photosynthetic epiparasitic plants, which contrary to virtuallyall other plants, exhibit high levels of specificity towardtheir fungal hosts. The second case involves suilloid fungi;this is the largest monophyletic group of ectomycorrhizal fungithat is essentially restricted to associations with a singleplant family. In both cases, new symbioses are initiated bydormant propagules that are stimulated to germinate by chemicalcues from the host. This reduces the cost of wasting propaguleson non-hosts. The advantages of specificity remain unclear inboth cases, but we argue that increased benefit to the specialistmay result from specialized physiological adaptations. We reexaminethe idea that specialist fungi may help their hosts competein complex ecosystems by reducing facultative epiparasitismby other plants, and suggest an alternative hypothesis for theobserved pattern.     

Organellar genes: why do they end up in the nucleus?

Many mitochondrial and plastid proteins are derived from their bacterial endosymbiotic ancestors, but their genes now reside on nuclear chromosomes instead of remaining within the organelle. To become an active nuclear gene and return to the organelle as a functional protein, an organellar gene must first be assimilated into the nuclear genome. The gene must then be transcribed and acquire a transit sequence for targeting the protein back to the organelle. On reaching the organelle, the protein must be properly folded and modified, and in many cases assembled in an orderly manner into a larger protein complex. Finally, the nuclear copy must be properly regulated to achieve a fitness level comparable with the organellar gene. Given the complexity in establishing a nuclear copy, why do organellar genes end up in the nucleus? Recent data suggest that these genes are worse off than their nuclear and free-living counterparts because of a reduction in the efficiency of natural selection, but do these population-genetic processes drive the movement of genes to the nucleus? We are now at a stage where we can begin to discriminate between competing hypotheses using a combination of experimental, natural population, bioinformatic and theoretical approaches.     

Protected areas in the world’s ecoregions: How well connected are they?

Protected areas (PAs) are the main instrument for biodiversity conservation, which has triggered the development of numerous indicators and assessments on their coverage, performance and efficiency. The connectivity of the PA networks at a global scale has however been much less explored; previous studies have either focused on particular regions of the world or have only considered some types of PAs.Here we present, and globally assess, ProtConn, an indicator of PA connectivity that (i) quantifies the percentage of a study region covered by protected connected lands, (ii) can be partitioned in several components depicting different categories of land (unprotected, protected or transboundary) through which movement between protected locations may occur, (iii) is easy to communicate, to compare with PA coverage and to use in the assessment of global targets for PA systems.We apply ProtConn to evaluate the connectivity of the PA networks in all terrestrial ecoregions of the world as of June 2016, considering a range of median dispersal distances (1–100 km) encompassing the dispersal abilities of the large majority of terrestrial vertebrates.We found that 9.3% of the world is covered by protected connected lands (average for all the world’s ecoregions) for a reference dispersal distance of 10 km, increasing up to 11.7% for the largest dispersal distance considered of 100 km. These percentages are considerably smaller than the global PA coverage of 14.7%, indicating that the spatial arrangement of PAs is only partially successful in ensuring connectivity of protected lands. The connectivity of PAs largely differed across ecoregions. Only about a third of the world’s ecoregions currently meet the Aichi Target of having 17% of the terrestrial realm covered by well-connected systems of PAs. Finally, our findings suggest that PAs with less strict management objectives (allowing the sustainable use of resources) may play a fundamental role in upholding the connectivity of the PA systems.Our analyses and indicator make it possible to identify where on the globe additional efforts are most needed in expanding or reinforcing the connectivity of PA systems, and can be also used to assess whether newly designated sites provide effective connectivity gains in the PA system by acting as corridors or stepping stones between other PAs. The results of the ProtConn indicator are available, together with a suite of other global PA indicators, in the Digital Observatory for Protected Areas of the Joint Research Centre of the European Commission.     

Breeding of Little Ringed Plovers Charadrius dubius in farmland: do nests in fields suffer from predation?

Capsule Fishponds and fields were equally attractive for breeding plovers, although predation on nests was higher in fishponds and extremely low in fields.     

Predictable spatial escapes from herbivory: how do these affect the evolution of herbivore resistance in tropical marine communities?

Summary Between-habitat differences in macrophyte consumption by herbivorous fishes were examined on three Caribbean and two Indian Ocean coral reefs. Transplanted sections of seagrasses were used as a bioassay to compare removal rates in reef-slope, reef-flat, sand-plain, and lagoon habitats. Herbivore susceptibility of fifty-two species of seaweeds from these habitats was also measured in the field. Seagrass consumption on shallow reef slopes was always significantly greater than on shallow reef flats, deep sand plains, or sandy lagoons. Reef-slope seaweeds were consistently resistant to herbivory while reef-flat seaweeds were consistently very susceptible to herbivory. This pattern supports the hypothesis that defenses against herbivores are costly in terms of fitness and are selected against in habitats with predictably low rates of herbivory.Sand-plain and lagoon seaweeds showed a mixed response when placed in habitats with high herbivore pressure; most fleshy red seaweeds were eaten rapidly, most fleshy green seaweeds were eaten at intermediate rates, and most calcified green seaweeds were avoided or eaten at very low rates. Differences in susceptibility between red and green seaweeds from sand-plain or lagoon habitats may result from differential competitive pressures experienced by these seaweed groups or from the differential probability of being encountered by herbivores. The susceptibility of a species to removal by herbivorous fishes was relatively consistent between reefs. Preferences of the sea urchin Diadema antillarum were also similar to those of the fish guilds.Unique secondary metabolites were characteristic of almost all of the most herbivore resistant seaweeds. However, some of the herbivore susceptible species also contain chemicals that have been proposed as defensive compounds. Genera such as Sargassum, Turbinaria, Thalassia, Halodule, and Thalassodendron, which produce polyphenolics or phenolic acids, were consumed at high to intermediate rates, suggesting that these compounds are not effective deterrents for some herbivorous fishes. Additionally, potential for the production of the compounds caulerpin, caulerpicin and caulerpenyne in various species of Caulerpa did not assure low susceptibility to herbivory.Heavily calcified seaweeds were very resistant to herbivory, but all of these species also produce toxic secondary metabolites which makes it difficult to distinguish between the effects of morphological and chemical defenses. Predictions of susceptibility to herbivory based on algal toughness and external morphology were of limited value in explaining differing resistances to herbivory.     

Invasive trees and shrubs: where do they come from and what we should expect in the future?

The global database of invasive trees and shrubs has been updated, resulting in a total of 751 species (434 trees and 317 shrubs) from 90 families (Rejmánek and Richardson 2013 Divers Distrib 19:1093–1094). This database is used to assess major trends in human-assisted exchanges of dendrofloras among 15 major geographical regions. Areas most invaded by non-native trees are Pacific Islands (136 species), Southern Africa (118), Australia (116), and North America (114). Areas most invaded by non-native shrubs are North America (98), Australia (87), Pacific Islands (71), and Europe (61). The most important sources of invasive trees are Asia (122–146 species, depending on how many Eurasian species are considered to have been introduced only from Europe), Australia (81), and South America (81). The most important sources of invasive shrubs are Asia (103–118), Europe (68), and South America (54). Mean number of native geographical regions for invasive trees is 1.64, while the mean number of invaded regions by trees is 2.51. The difference is smaller for shrubs: 1.60 versus 2.11. Asia is the major source of invasive Rosaceae shrubs, as well as invasive Arecaceae and Oleaceae species. South America and Australia are major sources of invasive Fabaceae trees. North America and Europe are major sources of invasive Pinaceae. Most of the invasive Salicaceae are of Eurasian origin. The identified trends will very likely continue in this century. Because of increasing interactions with many states in Asia, even more invasive woody species will be introduced from this part of the world.     

Rabbit (Oryctolagus cuniculus) abundance and protected areas in central-southern Spain: why they do not match?

European rabbits (Oryctolagus cuniculus), a keystone species in the Iberian Mediterranean ecosystem, are the staple prey of the Iberian lynx (Lynx pardinus) and the Spanish imperial eagle (Aquila adalberti). These predators require medium to high rabbit densities and a low degree of human disturbance. We compared rabbit abundances in areas of central-southern Spain under three levels of protection and management: protected areas, intensively managed (nonprotected) hunting estates, and other nonprotected areas. We used pellet abundance indices to estimate rabbit density in 118 surveys conducted during the summers of 2002 and 2003. We observed greater rabbit abundance in intensively managed hunting estates compared to protected areas and other nonprotected areas, perhaps because policy makers did not consider rabbit numbers when selecting priority areas. Alternatively, differences in game management practices (e.g., predator control or habitat management) may explain the higher rabbit densities observed in managed hunting estates. Our results suggest that the best feeding conditions for the Iberian lynx and the Spanish imperial eagle occur in intensively managed hunting areas, where such predators are frequently persecuted. The conservation of these endangered predators may require efforts to increase rabbit densities in protected areas.     

Tree seedlings: how do they establish in spontaneously developed forests? A study from a mountainous area in the Czech Republic

The aim of this study was to find out which tree species can establish in spontaneously developed forests (SDFs) on mesic stands and how many tree seedlings are present there. The influence of different factors was examined and an attempt made to find out if there are some general trends true for groups of species typical for different stages of succession or with different types of distribution. All tree seedlings present in 48 permanent plots were counted (100 m²). The following factors were tested: altitude, slope and exposition, distance from the nearest forest, age and species composition of tree layer, species composition of herb layer, light conditions and soil reaction. The species composition was dependent on altitude and soil reaction. There were surprisingly high numbers of seedlings (in average 145 tree seedlings per 100 m²) and species (in average 5) present in SDFs. Not only species common in the area were found, but also uncommon species were present there, although in low numbers. Nonspecific species are the best colonisers of SDFs, and the anemochorous trees are better colonisers than zoochorous ones. The establishment of different tree species is influenced by different factors. The SDFs most probably shift toward forest with a number of species in the tree layer. The dominant species tend to be spruce and maple, but species typical for early stages of succession will be common in these growths.     

Stress physiology in marine mammals: how well do they fit the terrestrial model?

Stressors are commonly accepted as the causal factors, either internal or external, that evoke physiological responses to mediate the impact of the stressor. The majority of research on the physiological stress response, and costs incurred to an animal, has focused on terrestrial species. This review presents current knowledge on the physiology of the stress response in a lesser studied group of mammals, the marine mammals. Marine mammals are an artificial or pseudo grouping from a taxonomical perspective, as this group represents several distinct and diverse orders of mammals. However, they all are fully or semi-aquatic animals and have experienced selective pressures that have shaped their physiology in a manner that differs from terrestrial relatives. What these differences are and how they relate to the stress response is an efflorescent topic of study. The identification of the many facets of the stress response is critical to marine mammal management and conservation efforts. Anthropogenic stressors in marine ecosystems, including ocean noise, pollution, and fisheries interactions, are increasing and the dramatic responses of some marine mammals to these stressors have elevated concerns over the impact of human-related activities on a diverse group of animals that are difficult to monitor. This review covers the physiology of the stress response in marine mammals and places it in context of what is known from research on terrestrial mammals, particularly with respect to mediator activity that diverges from generalized terrestrial models. Challenges in conducting research on stress physiology in marine mammals are discussed and ways to overcome these challenges in the future are suggested.     

Research in the exercise sciences: where do we go from here?

The goal of this article is to provide a perspective on how research involving the acute and chronic effects of exercise (referred to as "exercise sciences") on the structure and function of organs systems will evolve in the next century. Within the last 30 years, exercise-related research has rapidly transitioned from an organ to a subcellular/molecular focus. Thus future research will continue to be heavily influenced by molecular biology tools, fueled by both emerging technologies (e.g., "gene-chip microarrays") designed to dissect gene function on a macro scale as well as by the completion of the human genome project in which the approximately 80,000 genes comprising humans will be completely sequenced. These successes will drive the emerging fields of functional genomics (the dissecting of a gene's identity and function) and proteomics (the study of the properties of proteins). Funding levels at the National Institutes of Health will likely increase in order to expand these emerging fields as well as provide avenues for translating fundamental knowledge into solving the complexities of a number of degenerative diseases influenced heavily by activity/inactivity factors such as cardiopulmonary disease, diabetes, obesity, and the debilitating disorders associated with aging. Thus there are many challenges facing future exercise scientists who must harness the new technologies and take an aggressive stance in bringing this important field to the forefront.     

Dinophysis blooms in the deep euphotic zone of the Baltic Sea: do they grow in the dark?

In situ growth rates of the toxin-producing dinoflagellate Dinophysis norvegica collected in the central Baltic Sea were estimated during the summers of 1998 and 1999. Flow cytometric measurements of the DNA cell cycle of D. norvegica yielded specific growth rates (μ) ranging between 0.1 and 0.4 per day, with the highest growth rates in stratified populations situated at 15–20 m depth. Carbon uptake rates, measured using ¹⁴C incubations followed by single-cell isolation, at irradiances corresponding to depths of maximum cell abundance were sufficient to sustain growth rates of 0.1–0.2 per day. The reason for D. norvegica accumulation in the thermocline, commonly at 15–20 m depth, is thus enigmatic. Comparison of depth distributions of cells with nutrient profiles suggests that one reason could be to sequester nutrients. Measurements of single-cell nutrient status of D. norvegica, using nuclear microanalysis, revealed severe deficiency of both nitrogen and phosphorus as compared to the Redfield ratio.It is also possible that suitable prey or substrate for mixotrophic feeding is accumulating in the thermocline. The fraction of cells containing digestive vacuoles ranged from 2 to 22% in the studied populations. Infection by the parasitic dinoflagellate Amoebophrya sp. was observed in D. norvegica in all samples analysed. The frequency of infected cells ranged from 1 to 3% of the population as diel averages, ranging from 0.2 to 6% between individual samples. No temporal trends in infection frequency were detected. Estimated loss rates based on observed infection frequencies were 0.5–2% of the D. norvegica population daily, suggesting that these parasites were not a major loss factor for D. norvegica during the periods of study.     

Living on the edge: do central and marginal populations of plants differ in habitat suitability?

The performance of populations at the edge of specie’s distribution range may differ substantially from central populations. Here, we develop a modelling framework to estimate ecological niches (i.e. climatic) of four locally endangered plant species and measure the distance of marginal (geographically) populations to the species’ niche centroid in order to analyse whether marginal populations are outside of the optimal ecological niche of each species. Our results show that for three of the four studied species, which have their populations located at the margins of their distribution ranges, are also at the margins of their climate gradients. These results would support the hypothesis that marginality within the set of habitable conditions (i.e. ecological niche) may represent an important determinant on performance of some plant populations, as well as a plausible explanation to the degree of stagnancy or regression experienced by species in those regions where their populations are at the margin of their ecological niche and/or they are restricted to microrefugia with ecological conditions very different from those around them. Finally, this study aims to be a theoretical base from which to advance on, including other types of factors (e.g. biotic interactions, topography, human influence and population fluctuations through time), which will allow for a better understanding of the complex network of factors that occur in marginal plant populations.