Large body size constrains dispersal assembly of communities even across short distances.

Dispersal limitation has been considered to decrease with body size in animals and to be an important factor limiting community assembly on spatially isolated patches. Here we hypothesize that for flightless bark-dwelling oribatid mites dispersal limitation onto young trees might increase with body size (due to a decrease in aerial dispersal capacities), and it might occur even within a spatially contiguous forest canopy. We suppressed dispersal limitation towards branches from young trees by physically connecting them to branches from old trees and analyzed the impacts on community composition, accounting for branch microhabitat variables. Suppression of dispersal limitation increased community evenness and mean body size of mites on branches from young trees. Across all species, large species body-size corresponds to an abundance increase after suppression of dispersal limitation. Consistently, on no-contact control branches, mite body-sizes were larger on branches from old compared to young trees. Our study suggests that colonization/performance trade-offs might affect community assembly even across seemingly contiguous habitats. Overall, a previously underappreciated factor selecting against large body size in flightless canopy-dwelling invertebrates might be that large bodies makes these invertebrates fall faster and disperse less, not more.

How can screening for malnutrition among hospitalized patients be improved? An automatic e-mail alert system when admitting previously malnourished patients.

BACKGROUND & AIMS: Screening for malnutrition is not often done in the management of hospitalized patients. An original computer tool was developed at the Dunkerque hospital to detect readmissions of patients with malnutrition during a previous stay and generate e-mail alerts to the nutrition department. The aim of the study was to describe and evaluate this tool and the activity of the nutrition department in connection with the alerts sent. METHODS: The number of alerts sent, dietary consultations conducted, assessments of the nutritional status and the number of malnourished patients diagnosed were collected from September 1st to November 30th 2012. The positive predictive value (PPV) of the malnutrition screening tool was estimated. The evolution of the nutritional status between the last and the current hospitalization was also evaluated. RESULTS: A total of 531 e-mail alerts were sent (mean of 8.2 per working day), leading to 205 dietary consultations but only 144 recorded assessments of the nutritional status (lack of information in medical records). Of the latter, 128 diagnoses of malnutrition were made, i.e. a PPV of 88.9%, 95% Confidence Interval = [83.8%, 94%]. Overall, only one quarter of readmitted patients had improved nutritional status. CONCLUSIONS: The automatic e-mail alert system is operational and useful to effectively detect patients at risk of malnutrition and make follow up possible. In addition, an unfavorable evolution of the nutritional status of malnourished patients was observed.

Phytophagy on phylogenetically isolated trees: why hosts should escape their relatives.

Hosts belonging to the same species suffer dramatically different impacts from their natural enemies. This has been explained by host neighbourhood, that is, by surrounding host-species diversity or spatial separation between hosts. However, even spatially neighbouring hosts may be separated by many million years of evolutionary history, potentially reducing the establishment of natural enemies and their impact. We tested whether phylogenetic isolation of oak hosts from neighbouring trees within a forest canopy reduces phytophagy. We found that an increase in phylogenetic isolation by 100 million years corresponded to a 10-fold decline in phytophagy. This was not due to poorer living conditions for phytophages on phylogenetically isolated oaks. Neither species diversity of neighbouring trees nor spatial distance to the closest oak affected phytophagy. We suggest that reduced pressure by natural enemies is a major advantage for individuals within a host species that leave their ancestral niche and grow among distantly related species.