Does structural parasitism by epiphytes exist? A case study between Tillandsia recurvata and Parkinsonia praecox

The effects that epiphytes have on their hosts have been poorly explored in an experimentally. Correlational evidence suggests that epiphytes may be either mutualists or structural parasites, as has been proposed for Tillandsia recurvata on Parkinsonia praecox. To test the effect of T. recurvata upon P. praecox, the epiphyte load on branches of P. praecox was measured and two 1‐year experiments were performed to detect the effect of transplantation/removal of epiphytes and shade (0%, 35%. 50% and 80%) on shoot dynamics. If T. recurvata represents a selective pressure for P. praecox, then the frequency of branches carrying large epiphyte loads will be high, and host shoot survival will decrease in the presence of T. recurvata and with increased shade. A weak inverse relationship between epiphyte load and percentage of dead shoots in the host was detected. Shoot survival was independent of epiphyte presence. Shade decreased shoot survival by 35–72%. Results suggest that at the study site, T. recurvata is a commensalist of P. praecox. An alternative hypothesis to explain the correlation between high epiphyte load and branch/tree decay is that older branches carry more epiphytes, receive more shade from neighbouring branches and could be undergoing a natural decline process.     

Exclusion by interference competition? The relationship between red and arctic foxes

The distribution of many predators may be limited by interactions with larger predator species. The arctic fox in mainland Europe is endangered, while the red fox is increasing its range in the north. It has been suggested that the southern distribution limit of the arctic fox is determined by interspecific competition with the red fox. This has been criticised, on the basis that the species co-exist on a regional scale. However, if the larger red fox is superior and interspecific competition important, the arctic fox should avoid close contact, especially during the breeding season. Consequently, the distribution of breeding dens for the two species would be segregated on a much smaller spatial and temporal scale, in areas where they are sympatric. We tested this hypothesis by analysing den use of reproducing arctic and red foxes over 9 years in Sweden. High quality dens were inhabited by reproducing arctic foxes more often when no red foxes bred in the vicinity. Furthermore, in two out of three cases when arctic foxes did reproduce near red foxes, juveniles were killed by red foxes. We also found that breeding arctic foxes occupied dens at higher altitudes than red foxes did. In a large-scale field experiment, red foxes were removed, but the results were not conclusive. However, we conclude that on the scale of individual territories, arctic foxes avoid areas with red foxes. Through interspecific interference competition, the red fox might thus be excluding the arctic fox from breeding in low altitude habitat, which is most important in years when food abundance is limited and competition is most fierce. With high altitude refuges being less suitable, even small-scale behavioural effects could scale up to significant effects at the population level.     

Addressing positive impacts in social LCA—discussing current and new approaches exemplified by the case of vehicle fuels

Purpose

This paper seeks ways to address positive social impacts in social life cycle assessment (SLCA) and attempts to answer two questions: How can the SLCA methodology be improved in order to systematically identify all potential positive impacts in the supply chain? How can positive impacts be taken into consideration along with negative impacts in SLCA? In order for SLCA to be an attractive tool, it needs to provide users with the possibility to include positive impacts, not as variables stipulating lack of negative impacts but rather as fulfilment of positive potentials.

Methods

By scrutinising the social impacts addressed in the SLCA UNEP/SETAC Guidelines today and reviewing approaches for positive impacts in other research fields, a developed approach to capture and aggregate positive social impacts in SLCA is proposed. To exemplify the application, the case of vehicle fuels is used to investigate the possibilities of addressing positive impacts in SLCA. This includes a literature review on potential positive social impacts linked to vehicle fuels.

Results and discussion

The subcategories in the SLCA Guidelines are proposed to be divided into positive and negative impacts and complemented with some additional positive impacts. Related indicators are proposed. A draft approach for assessing positive impacts is developed where the proposed indicators are categorised in four different levels, from low to very high potential positive impact. The possibility to aggregate positive social impacts is discussed. Besides multi-criteria decision analysis (MCDA), few useful ideas for aggregating positive impacts in SLCA were found in the literature that mostly focused on surveys and monetarisation. Positive social impacts linked to vehicle fuels (fossil fuels and biofuels) are identified, and the proposed approach is schematically applied to vehicle fuels.

Conclusions

The SLCA methodology may be refined in order to better identify and assess positive impacts, and approaches developed for capturing and aggregating such impacts are proposed. Challenges of aggregating positive and negative social impacts still remain. The knowledge on social impacts from vehicle fuels could be improved by applying the proposed approach. However, the approach needs more development to be practically applicable.

     

Lipophilic drug transfer between liposomal and biological membranes: what does it mean for parenteral and oral drug delivery?

This review presents the current knowledge on the interaction of lipophilic, poorly water soluble drugs with liposomal and biological membranes. The center of attention will be on drugs having the potential to dissolve in a lipid membrane without perturbing them too much. The degree of interaction is described as solubility of a drug in phospholipid membranes and the kinetics of transfer of a lipophilic drug between membranes. Finally, the consequences of these two factors on the design of lipid-based carriers for oral, as well as parenteral use, for lipophilic drugs and lead selection of oral lipophilic drugs is described. Since liposomes serve as model-membranes for natural membranes, the assessment of lipid solubility and transfer kinetics of lipophilic drug using liposome formulations may additionally have predictive value for bioavailability and biodistribution and the pharmacokinetics of lipophilic drugs after parenteral as well as oral administration.     

Are carbon and nitrogen exchange between fungi and the orchid Goodyera repens affected by irradiance?

Background and Aims The green orchid Goodyera repens has been shown to transfer carbon to its mycorrhizal partner, and this flux may therefore be affected by light availability. This study aimed to test whether the C and N exchange between plant and fungus is dependent on light availability, and in addition addressed the question of whether flowering and/or fruiting individuals of G. repens compensate for changes in leaf chlorophyll concentration with changes in C and N flows from fungus to plant.Methods The natural abundances of stable isotopes of plant C and N were used to infer changes in fluxes between orchid and fungus across natural gradients of irradiance at five sites. Mycorrhizal fungi in the roots of G. repens were identified by molecular analyses. Chlorophyll concentrations in the leaves of the orchid and of reference plants were measured directly in the field.Key Results Leaf δ¹³C values of G. repens responded to changes in light availability in a similar manner to autotrophic reference plants, and different mycorrhizal fungal associations also did not affect the isotope abundance patterns of the orchid. Flowering/fruiting individuals had lower leaf total N and chlorophyll concentrations, which is most probably explained by N investments to form flowers, seeds and shoot.Conclusions The results indicate that mycorrhizal physiology is relatively fixed in G. repens, and changes in the amount and direction of C flow between plant and fungus were not observed to depend on light availability. The orchid may instead react to low-light sites through increased clonal growth. The orchid does not compensate for low leaf total N and chlorophyll concentrations by using a ¹³C- and ¹⁵N-enriched fungal source.     

How well is current plant trait composition predicted by modern and historical forest spatial configuration?

There is increasing evidence to suggest that a delayed response of many forest species to habitat loss and fragmentation leads to the development of extinction debts and immigration credits in affected forest habitat. These time lags result in plant communities which are not well predicted by present day landscape structure, reducing the accuracy of biodiversity assessments and predictions for future change. Here, species richness data and mean values for five life history characteristics within deciduous broadleaved forest habitat across Great Britain were used to quantify the degree to which aspects of present day forest plant composition are best explained by modern or historical forest patch area. Ancient forest specialist richness, mean rarity and mean seed terminal velocity were not well predicted by modern patch area, implying the existence of a degree of lag in British forest patches. Mean seedbank persistence values were more closely related to modern patch area than historical, particularly in larger patches. The variation in response for different mean trait values suggests that species respond to landscape change at different rates depending upon their combinations of different trait states. Current forest understorey communities are therefore likely to consist of a mixture of declining species whose extinction debt is still to be paid, and faster colonising immigrant species. These results indicate that without management action, rare and threatened species of plant are likely to be lost in the future as a result of changes in forest spatial configuration that have already taken place. The lag seen here for rare specialist plants suggests however that there may still be scope to protect such species before they are lost from forest patches.     

A rose by any other name? Rethinking the similarities and differences between male and female genital cutting

In this article, we offer a critical examination of the tendency to segregate discussion of surgical alterations to the male and female genitals into separate compartments--the first known as circumcision, the second as genital mutilation. We argue that this fundamental problem of definition underlies the considerable controversy surrounding these procedures when carried out on minors, and that it hinders objective discussion of the alleged benefits, harms, and risks. We explore the variable effects of male and female genital surgeries, and we propose a scale of damage for male circumcision to complement the World Health Organization's categorization of female genital mutilation. The origins of the double standard identified are placed in historical perspective, and in a brief conclusion we make a plea for greater gender neutrality in the approach to this contentious issue.     

Differences in acute stress responses between wild-caught and captive-bred birds: a physiological mechanism contributing to current avian invasions?

Current avian invasions are often the result of exotic birds accidentally escaping from cages. It has been hypothesised that the higher invasiveness of wild-caught cage-birds compared to captive-bred ones could be related to the loss of ability in captive-bred birds to cope with new environments. The acute stress response plays an important role in how animals cope with challenges because elevated corticosterone (CORT) levels can mediate learning and memory consolidation and help to increase their survival prospects. We experimentally tested whether exotic wild-caught and captive-bred cage-birds differ in their responses to acute stress using a representative sample of parrots. Wild-caught individuals showed longer CORT responses to acute stress than captive-bred ones, both at inter- and intra-specific levels when comparing wild-birds to the first generation born in captivity. Captive-bred birds may have attenuated their CORT responses due to acclimation, while high mortality rates during the international trade of wild-caught birds could have selected those individuals that are better able to cope with stress. We suggest that the longer acute response found in wild-caught parrots could help them to escape from cages and survive when facing challenges in new wild environments, possibly contributing to their higher invasiveness.     

Is diversification in male reproductive traits driven by evolutionary trade-offs between weapons and nuptial gifts?

Many male animals have evolved exaggerated traits that they use in combat with rival males to gain access to females and secure their reproductive success. But some male animals invest in nuptial gifts that gains them access to females. Both these reproductive strategies are costly in that resources are needed to produce the weapon or nuptial gift. In closely related species where both weapons and nuptial gifts are present, little is known about the potential evolutionary trade-off faced by males that have these traits. In this study, we use dobsonflies (order Megaloptera, family Corydalidae, subfamily Corydalinae) to examine the presence and absence of enlarged male weapons versus nuptial gifts within and among species. Many dobsonfly species are sexually dimorphic, and males possess extremely enlarged mandibles that they use in battles, whereas in other species, males produce large nuptial gifts that increase female fecundity. In our study, we show that male accessory gland size strongly correlates with nuptial gift size and that when male weapons are large, nuptial gifts are small and vice versa. We mapped weapons and nuptial gifts onto a phylogeny we constructed of 57 species of dobsonflies. Our among-species comparison shows that large nuptial gift production evolved in many species of dobsonfly but is absent from those with exaggerated weapons. This pattern supports the potential explanation that the trade-off in resource allocation between weapons and nuptial gifts is important in driving the diversity of male mating strategies seen in the dobsonflies, whereas reduced male–male competition in the species producing large spermatophores could be an alternative explanation on their loss of male weapons. Our results shed new light on the evolutionary interplay of multiple sexually selected traits in animals.     

Adult and juvenile dermatomyositis: are the distinct clinical features explained by our current understanding of serological subgroups and pathogenic mechanisms?

Adult and juvenile dermatomyositis share the hallmark features of pathognomic skin rash and muscle inflammation, but are heterogeneous disorders with a range of additional disease features and complications. The frequency of important clinical features such as calcinosis, interstitial lung disease and malignancy varies markedly between adult and juvenile disease. These differences may reflect different disease triggers between children and adults, but whilst various viral and other environmental triggers have been implicated, results are so far conflicting. Myositis-specific autoantibodies can be detected in both adults and children with idiopathic inflammatory myopathies. They are associated with specific disease phenotypes and complications, and divide patients into clinically homogenous subgroups. Interestingly, whilst the same autoantibodies are found in both adults and children, the disease features remain different within autoantibody subgroups, particularly with regard to life-threatening disease associations, such as malignancy and rapidly progressive interstitial lung disease. Our understanding of the mechanisms that underlie these differences is limited by a lack of studies directly comparing adults and children. Dermatomyositis is an autoimmune disease, which is believed to develop as a result of an environmental trigger in a genetically predisposed individual. Age-specific host immune responses and muscle physiology may be additional complicating factors that have significant impact on disease presentation. Further study into this area may produce new insights into disease pathogenesis.     

Rare and common species are doomed by climate change? A case study with neotropical butterflies and their host plants

Journal of Insect Conservation - Climate change is currently considered one key threat to biodiversity. Species with a restricted distribution possibly will be more affected than those with wide...     

How is adaptation to climate change reflected in current practice of forest management and conservation? A case study from Germany

Climate change is expected to challenge forest management and nature conservation in forests. Besides forest species, strategies and references for management and conservation will be affected. In this paper, we qualitatively analysed whether forest conservation and management practice have already adapted to the impacts of climate change and to what extent those practices reflect the adaptation strategies dealt with in international peer-reviewed literature. To this end, we conducted thirteen in-depth interviews with forest practitioners (forest officers/forest district officers) in four regions in Germany. The interview regions were selected to represent the variation in tree species composition, forest ownership regimes and vulnerability to climate change. Although interviewees claimed to take climate change and adaptation strategies into account, in practice such strategies have as yet only occasionally been implemented. Our results suggest that strategies for adapting forest management to climate change are just in the early stages of development or supplement existing strategies relating to general risk reduction or nature-orientated forest management. The extent to which climate change adaptation strategies have influenced overall management varies. This variation and the lack of specific strategies also reflect the existing uncertainties about future changes in climate and about the capacity of forest ecosystems to adapt. We conclude that, in the face of climate change, forest management will have a major influence on future biodiversity composition of forest ecosystems. Hence, a framework for conservation in forests providing recommendations which also take into account the consequences of climate change needs to be developed.     

The current status of evidence for and against postnatal oogenesis in mammals: a case of ovarian optimism versus pessimism?

Whether or not oogenesis continues in the ovaries of mammalian females during postnatal life was heavily debated from the late 1800s through the mid-1900s. However, in 1951 Lord Solomon Zuckerman published what many consider to be a landmark paper summarizing his personal views of data existing at the time for and against the possibility of postnatal oogenesis. In Zuckerman's opinion, none of the evidence he considered was inconsistent with Waldeyer's initial proposal in 1870 that female mammals cease production of oocytes at or shortly after birth. This conclusion rapidly became dogma, and remained essentially unchallenged until just recently, despite the fact that Zuckerman did not offer a single experiment proving that adult female mammals are incapable of oogenesis. Instead, 20 years later he reemphasized that his conclusion was based solely on an absence of data he felt would be inconsistent with the idea of a nonrenewable oocyte pool provided at birth. However, in the immortal words of Carl Sagan, an "absence of evidence is not evidence of absence." Indeed, building on the efforts of a few scientists who continued to question this dogma after Zuckerman's treatise in 1951, we reported several data sets in 2004 that were very much inconsistent with the widely held belief that germ cell production in female mammals ceases at birth. Perhaps not surprisingly, given the magnitude of the paradigm shift being proposed, this work reignited a vigorous debate that first began more than a century ago. Our purpose here is to review the experimental evidence offered in recent studies arguing support for and against the possibility that adult mammalian females replenish their oocyte reserve. "Never discourage anyone who continually makes progress, no matter how slow."-Plato (427-347 BC).     

New nature by sowing? The current state of species introduction in grassland restoration,and the road ahead

Semi-natural grasslands are some of the most threatened habitats on the planet, due to the abandonment of small-scale farming and its replacement with intensive agriculture. The fragmented landscape of today has created dispersal limitation that makes improbable the natural dispersal of target species into the remaining patches of grassland. This paper reviews the current status of species introduction into semi-natural grasslands, and summarises the results of published literature in this field. Our review shows that restoration through species introduction is an effective method of establishing dispersal limited species. However, the field of species introduction in restoration ecology has yet to make use of the value that Functional Diversity can add to restoration. No single study in our search has followed up species introduction by measuring any of the currently available indices of functional diversity. This approach is necessary to gain knowledge on what traits are likely to be sorted out in species introduction cases in various environments.