Impact of the alien plant Impatiens glandulifera on species diversity of invaded vegetation in the northern foothills of the Tatra Mountains,Central Europe

Plant Ecology - The impact of exotic annual Impatiens glandulifera on invaded European vegetation is ambiguous; there are studies reporting considerable negative as well as weak or even no impact...     

Population demography of the endangered large blue butterfly <Emphasis Type="Italic">Maculinea arion</Emphasis> in Europe

Demographic parameters such as survival, sex ratio and abundance can profoundly affect the viability of populations and thus are of primary importance in species of conservation concern. Although numerous studies have been published on certain aspects of the ecology and evolution of the endangered Large Blue butterfly Maculinea arion, there is still a lack of detailed knowledge on its populations’ demography. Moreover, M. arion populates a variety of xerothermic habitats throughout its European range using various food plants and host ants, which leads to complications in its conservation. Our aim was to estimate demographic parameters of M. arion populations in different parts of its European range. Detailed mark-recapture sampling was conducted on populations in four different countries. We often found that daily apparent survival probability declined with increasing age of individuals, but there was no difference between male and female survival. In smaller populations, the sex ratio was rather female-biased. Our most interesting result was the lack of protandry in some populations that might be a consequence of selection against reproductive asynchrony in small populations or a polyandrous mating system. The perfect coincidence of male and female phenology can positively affect the effective population size, because the lack of reproductive asynchrony increases the chance of male–female encounters. Abundance of the studied populations ranged between 100 and 1,600 individuals, smaller populations were on the verge of extinction. Habitat of the threatened small populations was either overgrazed or abandoned, while habitat of larger, stable populations was lightly grazed.     

A Longitudinal Study of Disability,Cognition and Gray Matter Atrophy in Early Multiple Sclerosis Patients According to Evidence of Disease Activity

New treatment options may make “no evidence of disease activity” (NEDA: no relapses or disability progression and no new/enlarging MRI lesions, as opposed to “evidence of disease activity” (EDA) with at least one of the former), an achievable goal in relapsing-remitting multiple sclerosis (RRMS). The objective of the present study was to determine whether early RRMS patients with EDA at one-year follow-up had different disability, cognition, treatment and gray matter (GM) atrophy rates from NEDA patients and healthy controls (HC). RRMS patients (mean age 34 years, mean disease duration 2.2 years) were examined at baseline and one-year follow-up with neurological (n = 72), neuropsychological (n = 56) and structural MRI (n = 57) examinations. Matched HC (n = 61) were retested after three years. EDA was found in 46% of RRMS patients at follow-up. EDA patients used more first line and less second line disease modifying treatment than NEDA (p = 0.004). While the patients groups had similar disability levels at baseline, they differed in disability at follow-up (p = 0.010); EDA patients progressed (EDSS: 1.8–2.2, p = 0.010), while NEDA patients improved (EDSS: 2.0–1.7, p<0.001). Cognitive function was stable in both patient groups. Subcortical GM atrophy rates were higher in EDA patients than HC (p<0.001). These results support the relevance of NEDA as outcome in RRMS and indicate that pathological neurodegeneration in RRMS mainly occur in patients with evidence of disease activity.     

Children and marital satisfaction in a non-Western sample: having more children increases marital satisfaction among the Igbo people of Nigeria

Previous research has demonstrated that having more children decreases marital satisfaction among parents. However, the universality of these findings is limited since the vast majority of the studies have been conducted in Western countries. In the present study, 374 people from the Igbo ethnic group (Nigeria) were assessed for levels of marital satisfaction and the number of children. In contrast to almost all previous findings, we found a positive relationship between the number of children and marital satisfaction among parents. Number of children was the strongest predictor of marital satisfaction even when compared to other variables like wealth and education. Our results suggest that the negative relationship between the number of children and marital satisfaction is not culturally universal and probably only characterizes developed, individualistic Western countries. We discuss our findings from a sociocultural and evolutionary perspective.     

Butterfly monitoring in Europe: methods,applications and perspectives

Since the first Butterfly Monitoring Scheme in the UK started in the mid-1970s, butterfly monitoring in Europe has developed in more than ten European countries. These schemes are aimed to assess regional and national trends in butterfly abundance per species. We discuss strengths and weaknesses of methods used in these schemes and give examples of applications of the data. A new development is to establish supra-national trends per species and multispecies indicators. Such indicators enable to report against the target to halt biodiversity loss by 2010. Our preliminary European Grassland Butterfly Indicator shows a decline of 50% between 1990 and 2005. We expect to develop a Grassland Butterfly Indicator with an improved coverage across European countries. We see also good perspectives to develop a supra-national indicator for climate change as well as an indicator for woodland butterflies.     

Growing islands and sinking solutes: processes maintaining the endorheic Okavango Delta as a freshwater system

In the Okavango Delta 98–99% of the water from inflow and rainfall is lost to the atmosphere through evapotranspiration. As a consequence 94% of inflowing solutes are retained within the Delta landscape. This process might be expected to result in an entirely saline environment, but that is not the case: the surface waters have very low salinity, supporting a typical freshwater biota. It has been deduced that the numerous islands in the Delta (about 150,000 within an area of 13,500 km²) have been formed through evapotransporative concentration in the groundwater, of infiltrating solutes, followed by precipitation and volume increase. Evidence of this is the large amount of calcrete in island soils. These islands of 3–10 m thickness with clayey soils are underlain by fine Kalahari sand to a depth of 200–300 m, which also indicates that they are formed through surface processes. The infiltration rate of surface water from floodplains and streams into islands is very high, and is predominantly a lateral process that is unidirectional. Evapotranspiration in the riparian woodland zone cause the ground-waters in the central area of islands—with halophyte grasslands—to have very high salinities. By use of chloride as a conservative element the concentration factor between central island groundwater and surface water is calculated to be 500–1,000. This groundwater is depleted of calcium and magnesium supporting the early deductions that these elements have precipitated as calcrete. There is also a large depletion of silicate and potassium that probably have precipitated as well forming the clayey soils typical of the islands. The central island groundwater is dominated by sodium, bicarbonate and dissolved organic matter. The gradual increase of salinity here causes a periodic let off of this water through a density-driven process to deeper layers. This process together with island growth through precipitation of solutes are the two major sink processes of inflowing solutes and explains why the Okavango Delta is at present a freshwater system. The whole island complex is calculated to be 100,000–400,000 years old while some intensely studied islands may be younger: 80,000–240,000 years. The discrepancy is explained by a biassed selection of islands currently in flooded areas with better growth conditions. The uniqueness of the Okavango Delta and ideas for future research are discussed.     

Size-assortative mating and sexual size dimorphism are predictable from simple mechanics of mate-grasping behavior

Background  

A major challenge in evolutionary biology is to understand the typically complex interactions between diverse counter-balancing factors of Darwinian selection for size assortative mating and sexual size dimorphism. It appears that rarely a simple mechanism could provide a major explanation of these phenomena. Mechanics of behaviors can predict animal morphology, such like adaptations to locomotion in animals from various of taxa, but its potential to predict size-assortative mating and its evolutionary consequences has been less explored. Mate-grasping by males, using specialized adaptive morphologies of their forelegs, midlegs or even antennae wrapped around female body at specific locations, is a general mating strategy of many animals, but the contribution of the mechanics of this wide-spread behavior to the evolution of mating behavior and sexual size dimorphism has been largely ignored.     

Patch occupancy and abundance of local populations in landscapes differing in degree of habitat fragmentation: a case study of the colonial black‐headed gull,Chroicocephalus ridibundus

Aim This study investigated whether habitat fragmentation at the landscape level influences patch occupancy and abundance of the black‐headed gull, Chroicocephalus ridibundus, and whether the response of the species to environmental factors is consistent across replicated landscape plots. Location Water bodies (habitat patches) in southern Poland. Methods Surveys were conducted in two landscape types (four plots in each): (1) more‐fragmented landscape, in which habitat patches were small (mean size 2.2–6.2 ha) and far apart (mean distance 2.5–3.1 km); and (2) less‐fragmented landscape, in which habitat patches were large (mean size 9.2–16.5 ha) and separated by short distances (mean 0.9–1.4 km). Observations were performed twice in 284 potential habitat patches during the 2007 breeding season. Results Colonies were significantly more frequent and larger in the less‐fragmented landscapes than in the more‐fragmented ones. Probability of patch occupancy and number of breeding birds were positively related with patch size and these relationships were especially strong in the more‐fragmented landscapes. In the less‐fragmented landscapes, the occurrence of black‐headed gulls was negatively related to the distance to the nearest local population, but in the more‐fragmented landscapes such a relationship was not detected. As distance to the nearest habitat patch increased, the probability of the patch occupancy decreased in the more‐fragmented landscapes. Moreover, abundance was negatively influenced by distance to the nearest habitat patch, especially strongly in more‐fragmented landscapes. Proximity of corridors (rivers) positively influenced the occupation of patches regardless of landscape type. The number of islets positively influenced occupancy and abundance of local populations, and this relationship was stronger in the more‐fragmented landscapes. Main conclusions Our results are in agreement with predictions from metapopulation theory and are the first evidence that populations of black‐headed gulls may have a metapopulation structure. However, patch occupancy and abundance were differentially affected by explanatory variables in the more‐fragmented landscapes than in the less‐fragmented ones. This implies that it is impossible to derive, a priori, predictions about presence/abundance patterns based on only a single landscape.     

By their own devices: invasive Argentine ants have shifted diet without clear aid from symbiotic microbes

The functions and compositions of symbiotic bacterial communities often correlate with host ecology. Yet cause–effect relationships and the order of symbiont vs. host change remain unclear in the face of ancient symbioses and conserved host ecology. Several groups of ants exemplify this challenge, as their low‐nitrogen diets and specialized symbioses appear conserved and ancient. To address whether nitrogen‐provisioning symbionts might be important in the early stages of ant trophic shifts, we studied bacteria from the Argentine ant, Linepithema humile – an invasive species that has transitioned towards greater consumption of sugar‐rich, nitrogen‐poor foods in parts of its introduced range. Bacteria were present at low densities in most L. humile workers, and among those yielding quality 16S rRNA amplicon sequencing data, we found just three symbionts to be common and dominant. Two, a Lactobacillus and an Acetobacteraceae species, were shared between native and introduced populations. The other, a Rickettsia, was found only in two introduced supercolonies. Across an eight‐year period of trophic reduction in one introduced population, we found no change in symbionts, arguing against a relationship between natural dietary change and microbiome composition. Overall, our findings thus argue against major changes in symbiotic bacteria in association with the invasion and trophic shift of L. humile. In addition, genome content from close relatives of the identified symbionts suggests that just one can synthesize most essential amino acids; this bacterium was only modestly abundant in introduced populations, providing little support for a major role of nitrogen‐provisioning symbioses in Argentine ant's dietary shift.