Are ecosystem services stabilized by differences among species? A test using crop pollination

Biological diversity could enhance ecosystem service provision by increasing the mean level of services provided, and/or by providing more consistent (stable) services over space and time. Ecological theory predicts that when an ecosystem service is provided by many species, it will be stabilized against disturbance by a variety of ‘stabilizing mechanisms.’ However, few studies have investigated whether stabilizing mechanisms occur in real landscapes affected by human disturbance. We used two datasets on crop pollination by wild native bees to screen for and differentiate among three stabilizing mechanisms: density compensation (negative co-variance among species' abundances); response diversity (differential response to environmental variables among species); and cross-scale resilience (response to the same environmental variable at different scales by different species). In both datasets, we found response diversity and cross-scale resilience, but not density compensation. We conclude that stabilizing mechanisms may contribute to the stability of pollination services in our study areas, emphasizing the insurance value of seemingly ‘redundant’ species. Furthermore, the absence of density compensation that we found at the landscape scale contrasts with findings of previous small-scale experimental and modelling work, suggesting that we should not assume that density compensation will stabilize ecosystem services in real landscapes

Molecular and Pathological characterization of a non-aganglionic congenital megacolon in the rabbit

Congenital megacolon (CM) is a severe colonic dysfunction usually associated with an underlying aganglionosis of the enteric nervous system (ENS). CM unrelated to aganglionosis may also occur with a largely unknown pathogenesis. Aim: to characterize a new, non-rodent natural model of non-aganglionic congenital megacolon. The CM phenotype is related to an incomplete dominant allele at the English spotting locus (En) and appears only in homozygous En/En animals. Methods: An F1 population of 80 animals was created crossing En/en rabbits. En/En rabbits (almost completely with a white fur due to the absence of melanocytes in the skin) and littermate controls (en/en) (normally coloured) have been monitored since birth up to severe deterioration of En/En animals with the CM phenotype. Cecum and ascending colon of controls (n=4) and CM (n=6) were processed for quantitative double label immunohistochemistry (using antibodies for structural and neurochemical markers of the ENS: Hu, substance P [SP] and neural nitric oxide synthase [nNOS]) and electron microscopy analysis. DNA was extracted from blood samples collected from all F1 animals and used for candidate gene analysis. Results: Compared to controls (en/en), En/En rabbits were subvital showing feeding abnormalities, reduced body weight and a massive colonic distension predominant in the cecum and ascending colon. Genetic tests confirmed the effects and segregation of the En alleles in the F1 population. Sequencing and genotyping of identified single nucleotide polymorphisms (SNP) in a few candidate genes showed complete co-segregation of a SNP in the KIT gene with the coat colour effects of the English spotting locus (LOD = 37.93; = 0.00). Quantitative gene expression in colon and cecum specimens showed that the level of Kit gene in En/En rabbits was only 5-10% vs that of en/en rabbits. Morphometric data on whole mounts of cecum and ascending colon showed a decreased number of Hu- and SP-immunoreactive (IR) neurons in En/En vs. en/en rabbits (950110 vs 1440120 and 7614 vs 16024, respectively; P<0.05). Although not statistically significant, nNOS-IR neurons were less abundant in En/En vs en/en. Compared to en/en, electron microscopy analysis of En/En tissues showed neuronal (rough endoplasmic reticulum with dilated cisternae, chaotically arranged cytoskeleton and nerve endings with empty synaptic vesicles) and interstitial cells of Cajal (ICC) (few cells with immature or altered features) abnormalities, particularly in the ascending colon. Conclusions: Combined neuronal and ICC network alterations underlie this non-aganglionic model of CM. Kit mutations may account for ICC abnormalities. The present findings can help understanding neuro-muscular changes occurring in human non-aganglionic C

A Choquet Integral Based Assessment Model of Projects of Urban Neglected Areas: a Case of Study

This paper describes a multi-criteria evaluation model to support decisions related to the redevelopment of urban residual areas, a central theme in planning practices. Renewal projects on urban or neighborhood scale are complex problems because of the social, economic and environmental implications generated on the different categories of stakeholders. In the awareness of the specific characteristics of each city, the cognitive and evaluation model is especially defined for a given urban context, although it is easily adaptable to different urban ones. In order to take into account the interactions among the criteria by which we compare design alternatives, the Choquet integral is implemented as aggregation function. The model applies to some alternative projects for the redevelopment of a residual urban area in Agrigento (Italy). It can be employed usefully by the local government to choose the better alternative project in pursuing the policy objectives or build new ones