Niche conservatism and species richness patterns of squamate reptiles in eastern and southern Africa

Niche conservatism has been proposed as a mechanism influencing large‐scale patterns of taxonomic richness. We document the species richness patterns of five monophyletic squamate reptile groups (gekkonids, cordylids‐scincids, lacertids, chameleons and alethinophidian snakes) in eastern and southern Africa, and explore if observed patterns reflect niche conservatism processes. We quantified richness and its relationships with current climatic conditions by gridding species' range maps at 110 × 110 km. Also, dated phylogenies and palaeoclimatic reconstructions, coupled with evidence from the fossil record, were used to approximate the areas and climate characteristics in which each group originated and/or radiated. Mean species richness and geographically corrected confidence intervals in current climate types were calculated for each group in order to establish their climatic preferences. On average, the species richness of older groups (gekkonids, cordylids‐scincids and lacertids) was lower in equatorial climates and higher in arid and temperate conditions, whereas more recent groups (chameleons and alethinophidian snakes) were richer in equatorial and temperate climates and less rich in arid conditions. Across all groups, higher richness was associated with climatic characteristics similar to those prevailing at the time in which each group originated/radiated. The congruence of the current climates where reptile groups are richer and the past climates amidst which those groups originated is consistent with an explanation for their diversity gradients based on niche conservatism.     

21st century climate change threatens mountain flora unequally across Europe

Continental‐scale assessments of 21st century global impacts of climate change on biodiversity have forecasted range contractions for many species. These coarse resolution studies are, however, of limited relevance for projecting risks to biodiversity in mountain systems, where pronounced microclimatic variation could allow species to persist locally, and are ill‐suited for assessment of species‐specific threat in particular regions. Here, we assess the impacts of climate change on 2632 plant species across all major European mountain ranges, using high‐resolution (ca. 100 m) species samples and data expressing four future climate scenarios. Projected habitat loss is greater for species distributed at higher elevations; depending on the climate scenario, we find 36–55% of alpine species, 31–51% of subalpine species and 19–46% of montane species lose more than 80% of their suitable habitat by 2070–2100. While our high‐resolution analyses consistently indicate marked levels of threat to cold‐adapted mountain florae across Europe, they also reveal unequal distribution of this threat across the various mountain ranges. Impacts on florae from regions projected to undergo increased warming accompanied by decreased precipitation, such as the Pyrenees and the Eastern Austrian Alps, will likely be greater than on florae in regions where the increase in temperature is less pronounced and rainfall increases concomitantly, such as in the Norwegian Scandes and the Scottish Highlands. This suggests that change in precipitation, not only warming, plays an important role in determining the potential impacts of climate change on vegetation.     

An approach to the knowledge of pollen and allergen diversity through lipid transfer protein localisation in taxonomically distant pollen grains

The aim of the present study is to localise non‐specific lipid transfer proteins (nsLTPs), obtained from Rosaceae (Prunus persica (L.) Batsch) in pollen grains of taxonomically distant plants, such as Iridaceae (Aristea latifolia G.J. Lewis), Platanaceae (Platanus acerifolia (Aiton) Willd.) and Urticaceae (Parietaria judaica L.), in order to compare pollen and nsLTP diversity. A combination of transmission electron microscopy, immunocytochemical techniques, and rabbit specific antiserum against peach nsLTPs (Pru p 3) were used. Abundant labelling to Pru p 3‐like proteins was observed in the cytoplasm, walls and pollenkitt of A. latifolia pollen grains. The presence of nsLTPs associated with the pollenkitt proves that it takes part in the defence mechanism of pollen grains. The labelling was less intense in the cytoplasm and walls of P. acerifolia. Immuno‐stained gold particles were associated with the vacuoles, lipid inclusions, endoplasmic reticulum and Golgi complex. No significant labelling was found in the P. judaica pollen grains incubated with anti‐Pru p 3 polyclonal antibodies. These results indicate important variations in the nsLTPs of different pollen species. Consequently, no taxonomic relationship between pollen grains and nsLTPs could be established.     

Drought resistance in early and late secondary successional species from a tropical dry forest: the interplay between xylem resistance to embolism,sapwood water storage and leaf shedding

The mechanisms of drought resistance that allow plants to successfully establish at different stages of secondary succession in tropical dry forests are not well understood. We characterized mechanisms of drought resistance in early and late‐successional species and tested whether risk of drought differs across sites at different successional stages, and whether early and late‐successional species differ in resistance to experimentally imposed soil drought. The microenvironment in early successional sites was warmer and drier than in mature forest. Nevertheless, successional groups did not differ in resistance to soil drought. Late‐successional species resisted drought through two independent mechanisms: high resistance of xylem to embolism, or reliance on high stem water storage capacity. High sapwood water reserves delayed the effects of soil drying by transiently decoupling plant and soil water status. Resistance to soil drought resulted from the interplay between variations in xylem vulnerability to embolism, reliance on sapwood water reserves and leaf area reduction, leading to a tradeoff of avoidance against tolerance of soil drought, along which successional groups were not differentiated. Overall, our data suggest that ranking species' performance under soil drought based solely on xylem resistance to embolism may be misleading, especially for species with high sapwood water storage capacity.     

IBERIAN AZURE-WINGED MAGPIE CYANOPICA (CYANA) COOKI NESTLINGS BEGGING CALLS: CALL CHARACTERIZATION AND HUNGER SIGNALLING

ABSTRACT

Nestling begging behaviour has long been seen as a signal by which nestlings solicit care from parents and most of the existing evidence provides some support for it being an honest signal. Begging is a multicomponent signal in which both sound and vision components are usually important. Although it is known that begging encodes information about nestling hunger the present knowledge about the specific behavioural features that convey the information is still scarce. The aim of this study was to describe begging calls of Iberian Azure-winged Magpie Cyanopica (cyana) cooki nestlings and examine how information on nestling hunger might be encoded in the begging calls. Nestlings were experimentally submitted to different periods of food deprivation and the call variation within individuals was studied. The young were individually tested and stimulated to beg by simulating parental visits. When subject to increasing food deprivation periods, nestlings increased the response level to simulated parental visits. The study also found that for the studied size differences, nestlings did not differ in their response level. Results confirmed that information on nestlings' hunger might be encoded in parameters of the calling behaviour. When the food deprivation periods increased, nestlings tended to start begging earlier, begged more often, extended their calling bout and increased the call duration, changing both at the level of the call and vocal begging bout. Overall the results support the view of begging as an honest signal, namely that begging should reflect nestling hunger and that only some call features might encode information about hunger.     

Reproductive features and gonad development cycle of the soft bottom-gravel gorgonian Leptogorgia sarmentosa (Esper, 1791) in the NW Mediterranean Sea

Abstract

Leptogorgia sarmentosa (Cnidaria: Octocorallia) is a common soft bottom-gravel gorgonian in the northwestern Mediterranean Sea. This study examined the annual reproductive cycle of a L. sarmentosa. population at a depth of 30 m, and further determined the sex ratio, the intra-colonial gonadal output variability and the age at first reproduction. L. sarmentosa was gonochoric and the population studied was characterized by a sex ratio slightly biased towards female colonies (1 male:1.6 female). Secondary branches had higher polyp fertility (number of gonads per polyp) compared to primary branches, but because of the number of polyps on the former, most of the sexual effort was actually contributed by the primary branches, as in other gorgonian species. Male colonies became fertile above a height of 21 cm, but female colonies had gonads even in the 1–10 cm height class. Spawning occurred between late August and early September, although there was no direct observation of broadcast spawning or surface brooder strategy. The maximum gonad size was 550 μm in males and 500 μm in females, with a mean diameter of 270 μm for spermaries, and 190 μm for eggs. The number of gonads per polyp prior to spawning reached 4–5 spermaries polyp!1 in male colonies, and 3–4 eggs polyp!1 in female colonies. Spawning did not appear to be synchronized with the full moon. L. sarmentosa appeared to have a different reproductive strategy to other Mediterranean gorgonians (living on hard bottom substrata), probably because of its different habitat preferences and biological (morphology, diet, prey capture rates, growth, biochemical levels) features.     

Aging Increases N epsilon -(Carboxymethyl)lysine and Caloric Restriction Decreases N epsilon -(Carboxyethyl)lysine and N epsilon -(Malondialdehyde)lysine in Rat Heart Mitochondrial Proteins

The present investigation studies the effect of aging, short-term and long-term caloric restriction on four different markers of oxidative, glycoxidative or lipoxidative damage to heart mitochondrial proteins: protein carbonyls (measured by ELISA); N epsilon -(carboxyethyl)lysine (CEL), N epsilon -(carboxymethyl)lysine (CML), and N epsilon -(malondialdehyde)lysine (MDA-lys) measured by gas chromatography/mass spectrometry. Aging increased the steady state level of CML in rat heart mitochondria without changing the levels of the other three markers of protein damage. Short-term caloric restriction (six weeks) did not change any of the parameters measured. However, long-term (one year) caloric restriction decreased CEL and MDA-lys in heart mitochondria and did not change protein carbonyls and CML levels. The decrease in MDA-lys was not due to changes in the sensitivity of mitochondrial lipids to peroxidation since the measurements of the fatty acid composition showed that the total number of fatty acid double bonds was not changed by caloric restriction. The decrease in CEL and MDA-lys in caloric restriction agrees with the previously and consistently described finding that caloric restriction agrees with the previously and consistently described finding that caloric restriction lowers the rate of generation of reactive oxygen species (ROS) in rodent heart mitochondria, although in the case of CEL a caloric restriction-induced lowering of glycaemia can also be involved. The CEL and MDA-lys results support the notion that caloric restriction decreases oxidative stress-derived damage to heart mitochondrial proteins.     

Autoantibodies Enhance Agonist Action and Binding to Cardiac Muscarinic Receptors in Chronic Chagas' Disease

Chronic Chagasic patient immunoglobulins (CChP-IgGs) recognize an acidic amino acid cluster at the second extracellular loop (el2) of cardiac M₂-muscarinic acetylcholine receptors (M₂AChRs). These residues correspond to a common binding site for various allosteric agents. We characterized the nature of the M₂AChR/CChP-IgG interaction in functional and radioligand binding experiments applying the same mainstream strategies previously used for the characterization of other allosteric agents. Dose-response curves of acetylcholine effect on heart rate were constructed with data from isolated heart experiments in the presence of CChP or normal blood donor (NBD) sera. In these experiments, CChP sera but not NBD sera increased the efficacy of agonist action by augmenting the onset of bradyarrhythmias and inducing a Hill slope of 2.5. This effect was blocked by gallamine, an M₂AChR allosteric antagonist. Correspondingly, CChP-IgGs increased acetylcholine affinity twofold and showed negative cooperativity for [³H]-N-methyl scopolamine ([³H]-NMS) in allosterism binding assays. A peptide corresponding to the M₂AChR-el2 blocked this effect. Furthermore, dissociation assays showed that the effect of gallamine on the [³H]-NMS off-rate was reverted by CChP-IgGs. Finally, concentration-effect curves for the allosteric delay of W84 on [³H]-NMS dissociation right shifted from an IC₅₀ of 33 nmol/L to 78 nmol/L, 992 nmol/L, and 1670 nmol/L in the presence of 6.7 × 10^{? 8}, 1.33 × 10^{? 7}, and 2.0 × 10^{? 7} mol/L of anti-el2 affinity-purified CChP-IgGs. Taken together, these findings confirmed a competitive interplay of these ligands at the common allosteric site and revealed the novel allosteric nature of the interaction of CChP-IgGs at the M₂AChRs as a positive cooperativity effect on acetylcholine action.     

Leaf anatomical studies of Chamaecrista subsect. Baseophyllum (Leguminosae, Caesalpinioideae): new evidence for the up-ranking of the varieties to the species level

This study aims to determine whether morphoanatomical characters of the leaves of the species of Chamaecrista sect. Absus subsection Baseophyllum could be used to support an up-ranking of C. cytisoides varieties to the species level as previously defined by molecular studies. The significance of anatomical adaptive strategies to arid environments is also discussed. Standard light microscopy techniques and histochemical tests were used for both morphoanatomical and histochemical characterization of the leaves. All the species studied share a single-layered epidermis, actinodromous–camptodromous–brochidodromous type of venation, vascular bundles surrounded by layers of fibers bounded externally by a sheath of cells containing solitary crystals, enlarged tracheids at the vein endings, vascular petiole/rachis tissue with a parenchymatous pith, accessory vascular bundles, mucilage idioblasts and hypodermis in the mesophyll, colleters, and non-secretory trichomes. The position and type of stomata, type of mesophyll, number of palisade and spongy parenchyma layers, position of mucilage idioblasts in the mesophyll, and the number of accessory vascular bundles of petiole/rachis provided useful characters for discriminating the eight species of the subsect. Baseophyllum. Histochemical tests reveal the presence of total polysaccharides, pectins, mucilage and phenolic compounds in the idioblasts. Other xeromorphic characters such as thickened outer periclinal cell walls, compact mesophyll, mucilage idioblasts and hypodermis in the mesophyll may help enable the studied species to survive in exposed sunny areas.     

Culex pipiens and Stegomyia albopicta (= Aedes albopictus) populations as vectors for lineage 1 and 2 West Nile virus in Europe

The emerging disease West Nile fever is caused by West Nile virus (WNV), one of the most widespread arboviruses. This study represents the first test of the vectorial competence of European Culex pipiens Linnaeus 1758 and Stegomyia albopicta (= Aedes albopictus) (both: Diptera: Culicidae) populations for lineage 1 and 2 WNV isolated in Europe. Culex pipiens and S. albopicta populations were susceptible to WNV infection, had disseminated infection, and were capable of transmitting both WNV lineages. This is the first WNV competence assay to maintain mosquito specimens under environmental conditions mimicking the field (day/night) conditions associated with the period of maximum expected WNV activity. The importance of environmental conditions is discussed and the issue of how previous experiments conducted in fixed high temperatures may have overestimated WNV vector competence results with respect to natural environmental conditions is analysed. The information presented should be useful to policymakers and public health authorities for establishing effective WNV surveillance and vector control programmes. This would improve preparedness to prevent future outbreaks.