Phengaris (Maculinea) teleius butterflies select host plants close to Myrmica ants for oviposition, but P. nausithous do not

Many lycaenid butterfly species have interactions with ants, with 12% obligatorily depending on two sequential sources of larval food, namely host plants and host ants. When host plants are abundant but the density of host ant nests is relatively low, most host plants have no host ant nest in their vicinity and are thus unsuitable for larval survival. Obligatorily myrmecophilous female butterflies, whose caterpillars feed on ant larvae, would have a comparative advantage if they deposit eggs on host plants in the proximity of a host ant nest. However, this ant-mediated oviposition has been hotly debated. In an open-air insectory experiment, we tested whether oviposition is ant-mediated or not for two obligatory myrmecophilous butterfly species, Phengaris (Maculinea) nausithous Bergsträsser and Phengaris teleius Bergsträsser (Lepidoptera: Lycaenidae). Female butterflies could select host plants close to either no ant nest or a nest of one of the two Myrmica species (Hymenoptera: Formicidae) that are thought to be their host ant. Our results support ant-mediated oviposition in P. teleius, but also indicate that there is no preference for either of the Myrmica species. More eggs were deposited and more caterpillars were found on long flowerheads close to Myrmica ant nests than on those without nests. Our findings suggest that ant presence is more important than flowerhead phenology for females of P. teleius. In contrast, P. nausithous females were not attracted by ants but preferred long flowerheads with a low percentage of green coloration. With these findings, this study contributes to better understanding of the habitat requirements of two highly specialized butterfly species

Combining forces. Distributed Leadership and a professional learning community in primary and secondary education

This report describes an in depth case study of two good practice schools where a professional learning community and distributed leadership are highly developed. The goal of this study was to learn what conditions in the school support a professional learning community and distributed leadership. We gave specific attention to the supporting role of the school leader. The importance of continuous school improvement is self-evident and is achieved when teachers and school leaders collaboratively address educational issues, also known as a professional learning community (PLC). Within a PLC, school leaders and teachers alike must have the opportunity to take influence. Leadership is therefore not only exercised by the school leader, but is based on expertise, talents and qualities that are necessary for the issues at hand. This is known as distributed leadership (DL). A PLC and DL are combining forces, the sum of both drives the process of school improvement. However, as a previous study shows, teachers and school leaders still often struggle to collaborate and to make use of each other’s expertise. After an elaborate selection process - through an online survey and group interviews - two schools in The Netherlands were identified as good practices of a PLC and DL. The selected good practices are: primary school ‘Willibrordus’ and secondary school ‘Vathorst College’. We visited these schools and spoke with and observed teachers and school leaders. In the good practice schools, school leaders combine an informal role to support DL and a PLC and formal tools to necessitate and enable it. Most strikingly is that at Willibrordus and Vathorst the daily work- and educational practices are organised to enable and entice teachers to work together on school improvement and innovation. It seems that these collaborative practices - that are absent in most schools - are what lay the base for DL and a PLC. However, these practices are not sufficient. Additionally, within such a practice teachers and school leaders alike must show or develop the ability to professionally communicate with each other. At Vathorst College and Willibrordus this professional conversation entails giving constructive feedback, communicating openly and approaching the other respectfully. Other highlights from these descriptions are the following. Willibrordus and Vathorst College show a culture that is characterised by a large amount of teacher autonomy, creativity and cooperation between teachers. Both schools lay a strong emphasis on professional development (formally organised and informally supported) that helps teachers to gain new ideas and take influence from their acquired expertise. Finally, in both schools school leaders and teachers hold clear professional expectations of each other. In addition to the insight in the practice of two schools, this study concludes with the following recommendations for school leaders and teachers to stimulate a PLC and DL in their school: • Create practices that make collaboration inevitable. • Communicate through a professional dialogue. • Make radical decisions about the educational practice in line with the school’s vision. • Discuss what it means to be a professional at your school

Modelling honey bee colonies in winter using a Keller-Segel model with a sign-changing chemotactic coefficient

Thermoregulation in honey bee colonies during winter is thought to be self-organised. We added mortality of individual honey bees to an existing model of thermoregulation to account for elevated losses of bees that are reported worldwide. The aim of analysis is to obtain a better fundamental understanding of the consequences of individual mortality during winter. This model resembles the well-known Keller-Segel model. In contrast to the often studied Keller-Segel models, our model includes a chemotactic coefficient of which the sign can change as honey bees have a preferred temperature: when the local temperature is too low, they move towards higher temperatures, whereas the opposite is true for too high temperatures. Our study shows that we can distinguish two states of the colony: one in which the colony size is above a certain critical number of bees in which the bees can keep the core temperature of the colony above the threshold temperature, and one in which the core temperature drops below the critical threshold and the mortality of the bees increases dramatically, leading to a sudden death of the colony. This model behaviour may explain the globally observed honey bee colony losses during winter.Comment: 20 pages, 12 figure

veining: landscape determinants of biodiversity in European agricultural landscapes

Abstract Many semi-natural landscape elements, the so-called green veining, are disappearing from the intensively used agricultural landscapes of Europe. In order to develop or restore biodiversity in these networks, it is necessary to quantify the relation between biodiversity and amount, spatial arrangement and management intensity of green veining elements. In this review, we investigate whether biodiversity increases with the amount of green veining in an agricultural landscape following the species-area relationship, and whether a certain level of biodiversity can be reached at lower densities of green veining if green veining elements are better connected (higher spatial connectivity) or if they are managed less intensively (lower management intensity). We reviewed studies on aboveground biodiversity in green veining structures in 39 scientific papers on field and experimental studies within Europe. More of these studies focussed on management intensity than on amount or spatial configuration of green veining. Also more studies focussed on the spatial scale of individual landscape elements than on the farm or landscape scale, which may be caused by the large number of studies focussing on plant or invertebrate species. Species living at larger spatial scales, e.g. mammals and birds were not often studied at the level of green veining elements as they also use agricultural fields as part of their habitat. We could not verify the species-area relation for green veining, nor the effect of amount, spatial configuration or management intensity on this relation, because only few studies quantified the found effects and no studies were found on the effect of management intensity or spatial configuration on the species-area curve in green veining. We addressed the most important challenges for future field and model research in order to fill the identified gaps in knowledge

Bouwstenen voor een professionele leergemeenschap in de school. Gespreid leiderschap

Het Welten-instituut van de Open Universiteit deed op twee scholen onderzoek naar gespreid leiderschap in de school. Gespreid leiderschap betekent dat niet alleen de schoolleider leiderschap verwerft, maar dat ook leraren invloed kunnen uitoefenen in de school. Maar hoe doe je dat? De onderzoekers delen zes bouwstenen ter inspiratie

Disturbanceediversity relationships for soil fauna are explained by faunal community biomass in a salt marsh

a b s t r a c t Disturbanceediversity relationships have long been studied in ecology with a unimodal relationship as the key prediction. Although this relationship has been widely contested, it is rarely tested for soil invertebrate fauna, an important component of terrestrial biodiversity. We tested disturbanceediversity relationships for soil meso-and macrofauna in a salt marsh where periodic sea water inundation and cattle grazing occur as stressors. We hypothesized a unimodal inundation frequencyediversity relationship, whereas we expected grazing to overrule the effects of inundation frequency due to its large effects on the habitat of soil fauna. We found a negative relationship between inundation frequency and diversity at the ungrazed sites and no relationship at the grazed sites. Moreover, we found a negative relationship between community biomass and diversity for soil fauna that may have caused this negative disturbanceediversity relationship. Community biomass at the intermediate inundation frequency increased due to the dominance of Orchestia gammarellus (a macro-detritivore species), which could exploit low quality litters at the ungrazed sites. We highlight that the negative relationship between faunal community biomass and faunal diversity may influence disturbanceediversity relationships and illustrate that total biomass distribution of feeding guilds of soil fauna can improve our understanding of the soil fauna response to stressors in salt marshes

Movement Patterns of African Elephants (Loxodonta africana) in a Semi-arid Savanna Suggest That They Have Information on the Location of Dispersed Water Sources

Water is a scarce resource in semi-arid savannas where over half of the African elephants (Loxodonta africana) populations occur and may therefore influence their movement pattern. A random search is expected for an animal with no information on the location of the target resource, else, a direction-oriented walk is expected. We hypothesized that elephants movement patterns show a stronger directional orientation toward water sources in the dry season compared to the wet season. We investigated the movement paths of four male and four female elephants with hourly GPS fixes in Tsavo National Park, Kenya in 2012–2013. Consistent with our predictions, the movement paths of elephants had longer step lengths, longer squared net displacements, and were directed toward water sources in the dry season as compared to the wet season. We argue that African elephants know the location of dispersed water resources, enabling them to survive with scarce resources in dry savannas. These results can be used in conservation and management of wildlife, through for instance, protection of preferred water sources

MODIS VCF should not be used to detect discontinuities in tree cover due to binning bias. A comment on Hanan et al. (2014) and Staver and Hansen (2015)

In their recent paper, Staver and Hansen (Global Ecology and Biogeography, 2015, 24, 985-987) refute the case made by Hanan et al. (Global Ecology and Biogeography, 2014, 23, 259–263) that the use of classification and regression trees (CARTs) to predict tree cover from remotely sensed imagery (MODIS VCF) inherently introduces biases, thus making the resulting tree cover unsuitable for showing alternative stable states through tree cover frequency distribution analyses. We here provide a new and equally fundamental argument why the published frequency distributions should not be used for such purposes. We show that the practice of pre-average binning of tree cover values used to derive cover values to train the CART model will also introduce errors in the frequency distributions of the final product. We demonstrate that the frequency minima found at tree covers 8 % to 18 %; 33 % to 45 %; and 55 % to 75 % can be attributed to numerical biases introduced when training samples are derived from landscapes containing asymmetric tree cover distributions and/or a tree cover gradient. So it is highly likely that the CART, used to produce MODIS VCF, delivers tree cover frequency distributions that do not reflect the real world situation