المرأة في خطاب التنوير عند جابر عصفور Al-Mar’a fi khitab al-tanwir ‘ind Gaber Asfour

Women, freedom, the Renaissanc

Pollinating animals in the urban environment

Urban environments contain habitats for flowering plants and their pollinating animal species. It is, however, unclear how the urban matrix influences plant-pollinator processes. We recorded plant diversity, floral abundance, flower visitor diversity and plot visits at 89 plant patches within the city of Zürich. The urban matrix surrounding each site was analyzed for the landscape metrics edge density and the extent of green area up to 200m radius. The correlation between edge density and bee diversity and visitation frequency varied over the entire spatial range, while the correlation for syrphid diversity and visitation frequency levelled off at 80m radius. In contrast, the correlations with green area were more consistent, with bee diversity levelling off after 100m, while syrphid diversity and visits continued to increase. The variation in the correlation of bee visits was partly accounted for by the large contribution of honeybees. Plant diversity significantly affected bee diversity and visits, and syrphid visits. Floral abundance had a positive effect on bee visits and bee diversity. Syrphid diversity had a negative interaction with floral abundance and green area. The extent of green area increased bee diversity and visits, and syrphid visits, while edge density reduced visitation by bees. This study showed that plant diversity and floral abundance in urban environments promote pollinating flower visitors. The extent of green area and edge density are important urban mosaic attributes that affect pollinator abundance and visitation frequency at multiple scale

Genetic variation and plant performance in fragmented populations of globeflowers ( Trollius europaeus ) within agricultural landscapes

The management of remnant populations in highly fragmented landscapes requires a thorough understanding of the processes shaping population persistence. We investigated relationships between population characteristics (i.e. size, density and pollinator abundance), offspring performance, genetic diversity and differentiation in Trollius europaeus, a plant with a nursery pollination system. In 19 populations of different sizes and located in north-east Switzerland, an area which has undergone widespread land use changes over the last decades, we assessed neutral genetic diversity (N total=383) using AFLPs and plant performance in a greenhouse experiment (N total=584) using competition and control treatments. Overall genetic differentiation was low (F ST=0.033) with a marginal significant isolation by distance effect (P=0.06) indicating (historical) genetic connectivity among the populations. Mean expected heterozygosity was H E of 0.309 (0.0257-0.393) while inbreeding coefficients (F IS) were significant in only three populations. Genetic diversity was not related to population size, plant density or pollinator abundance. Plant performance was reduced under competition (P<0.001) but the severity of competition was independent of genetic diversity and population size. In summary, remnant populations of T. europaeus retain genetic diversity and seem capable of persisting under the present conditions within an agricultural matrix. T. europaeus is a perennial herb, thus it may require several generations for the negative effects of fragmentation and isolation to manifest. Our findings indicate that small populations are as important as large populations for the conservation and management of genetic resource

Der Einfluss der Honigbienen auf Pflanzen-Bestäuber-Netzwerke in den Schweizer Alpen

Der kontinuierliche Rückgang der Landwirtschaftsfläche in der Schweiz führt dazu, dass die verbleibenden Flächen bei einem jährlichen Einsatz von 2200 t Pestiziden zunehmend intensiver und in grösseren Einheiten bewirtschaftet werden. Die heute dominierenden, an Blütenpflanzen und Kleinstrukturen armen «grünen Wüsten» bieten kaum noch Nahrung für Honigbienen. Der intensive Einsatz von Pestiziden und die geringen Nahrungsressourcen schwächen die Honigbienen. In Verbindung mit einem Befall durch die Varroa-Milbe kann dies zur Erkrankung der Bienen und zum Tod ganzer Völker führen. Die Schweizer Bundesverwaltung ist dabei, Massnahmen zur Förderung der Honigbienen 3 auszuarbeiten. Bis diese Massnahmen greifen, könnten Imker ihre Völker zur Stärkung in die Schweizer Alpen verlegen, wo mehr extensiv bewirtschaftete Flächen und Nahrungsquellen vorhanden sind. Vor diesem Hintergrund wurde untersucht, welchen Einfluss Honigbienen in den Alpen auf die einheimischen Pflanzen-Bestäuber-Netzwerke haben

Development of polymorphic microsatellite markers of the endangered and endemic Vateriopsis seychellarum (Dipterocarpaceae), a relict canopy tree of the Seychelles

The Dipterocarpaceae are a globally significant family of tropical timber trees. They are especially dominant in lowland rainforests of Southeast Asia, but have a pan tropical distribution. Vateriopsis seychellarum is the sole representative of this family on the Seychelles. Historically one of the dominant canopy trees on Mahé, extensive overexploitation of this species for its timber has led to its virtual extinction. The last individuals of this species are found in small fragmented populations at lower altitudes (up to 400m) on the island of Mahé where the total number of known reproductive adults is 112. We developed ten polymorphic microsatellite loci for this species to enable us to quantify the levels of diversity in remnant populations and to study genetic structure and contemporary gene flow. In addition we tested for cross amplification of these alleles in the closely related but geographically disjunct species Vateria indica. In Vateriopsis seychellarum the number of alleles per locus ranged from 6 to 20 (mean of 11.4 per locus) with an average polymorphic information content of 0.73 across loci. Expected heterozygosity ranged from 0.40 to 0.71 with 3 of the 10 loci showing deviation from Hardy-Weinberg expectations. 8 of the 10 primers showed cross amplification in Vateria indica. These markers will help to provide a better understanding of the significance of historic distributions, gene flow and recent anthropogenic habitat degradation for the survival of widespread species in recently fragmented landscape

Geographic variation in the morphology and behavioural ecology of a sphecid wasp

A comparative study between populations of Mellinus arvensis (Hymenoptera: Sphecidae) was carried out in Britain. Large variations in size were found between populations and these were correlated with environmental, thermal, and biological factors. A latitudinal dine accounted for some of the variation, with larger wasps found at southerly locations. This was partially explained by climatic patterns and wasp warm-up rates. A hypothesis involving the interaction of environmental, behavioural and morphological factors was suggested to account for the remaining unexplained size variation between populations. It was found that at sites where the ground is compact and difficult to dig through, nests are more valuable in terms of time required to dig them. A strategy of searching for rather than digging a nest becomes viable. Wasps do not seem to be able to distinguish between occupied and abandoned nests, and aggressive interactions at nests occur between wasps searching for a nest and the nest residents. Aggression is more frequent at sites where pressure from searchers is greatest, that is, at sites where nest construction is most difficult and costly. Consequently, large wasps, which have greater success in aggressive encounters, are selected for at these sites. At sites where the ground is loose and easy to dig through, a more successful reproductive tactic appears to be maximisation of offspring number, resulting in many, small offspring. Behavioural observations suggested that M. arvensis is capable of, at least, limited endothermy, although this could not be confirmed in laboratory experiments. Similar observations and results were obtained from several other sphecid species. However, endothermy was found in two sphecid species of the genus Bembix in Portugal, suggesting that endothermy may be more widespread than previously thought