Plant phylogeny drives arboreal caterpillar assemblages across the Holarctic

1. Assemblages of insect herbivores are structured by plant traits such as nutrient content, secondary metabolites, physical traits, and phenology. Many of these traits are phylogenetically conserved, implying a decrease in trait similarity with increasing phylogenetic distance of the host plant taxa. Thus, a metric of phylogenetic distances and relationships can be considered a proxy for phylogenetically conserved plant traits and used to predict variation in herbivorous insect assemblages among co‐occurring plant species.
2. Using a Holarctic dataset of exposed‐feeding and shelter‐building caterpillars, we aimed at showing how phylogenetic relationships among host plants explain compositional changes and characteristics of herbivore assemblages.
3. Our plant–caterpillar network data derived from plot‐based samplings at three different continents included >28,000 individual caterpillar–plant interactions. We tested whether increasing phylogenetic distance of the host plants leads to a decrease in caterpillar assemblage overlap. We further investigated to what degree phylogenetic isolation of a host tree species within the local community explains abundance, density, richness, and mean specialization of its associated caterpillar assemblage.
4. The overlap of caterpillar assemblages decreased with increasing phylogenetic distance among the host tree species. Phylogenetic isolation of a host plant within the local plant community was correlated with lower richness and mean specialization of the associated caterpillar assemblages. Phylogenetic isolation had no effect on caterpillar abundance or density. The effects of plant phylogeny were consistent across exposed‐feeding and shelter‐building caterpillars.
5. Our study reveals that distance metrics obtained from host plant phylogeny are useful predictors to explain compositional turnover among hosts and host‐specific variations in richness and mean specialization of associated insect herbivore assemblages in temperate broadleaf forests. As phylogenetic information of plant communities is becoming increasingly available, further large‐scale studies are needed to investigate to what degree plant phylogeny structures herbivore assemblages in other biomes and ecosystems.

     

Comparative in vitro and in vivo beta-oxidation of N-nitrosodiethanolamine in different animal species

The metabolism of N-nitrosodiethanolamine (NDELA) was studied to assess whether the formation of the beta-oxidated metabolites N-(2-hydroxyethyl)-N-(formylmethyl)nitrosamine (EFMN) and N-(2-hydroxyethyl)-N-(carboxymethyl)nitrosamine (ECMN) is involved in the mechanism of tumor induction in various animal species with different susceptibility to NDELA carcinogenicity. In vitro studies using liver S9 fractions from rats, hamster, B6C3F1 and CD-1 mice and rabbits showed that all the animal species metabolize NDELA through the beta-oxidation pathway, although to different extents. Urinary excretion of NDELA and its metabolite ECMN in rats, hamsters and mice after 5 mg X kg-1 NDELA i.p. confirmed these findings. The results suggest there is no correlation between carcinogenesis by NDELA and its beta-oxidation. The possibility that ECMN formation might represent a detoxifying metabolic pathway for NDELA is discussed.     

Skipper impoverishment on large West Mediterranean islands (Lepidoptera Hesperioidea): deterministic,historical and stochastic factors

Biogeographical analyses are applied to skipper (Hesperioidea) presence/absence data from the Western Mediterranean mainland and the three largest islands (Sardinia, Corsica and Sicily) in order to identify potential conservation issues. The analyses performed on species, both collectively and individually, indicate that regional species richness and occurrence in the Mediterranean zone are largely predicted by latitude and area but that islands have impoverished faunas. Several species, predicted to be present on these islands from logistic regression of their continental distributions, are actually absent. The number of species predicted to be present from logistic regression analyses for each island, closely matched the number of species predicted to occur in regional-focused multiple regression analysis. This suggests that missing species have been identified. When compared with species that occur in Sicily and Corsica, the missing species are shown to differ for ecological traits, mainly those linked to altitudinal tolerance. No ecological distinctions were disclosed for Sardinian skippers suggesting a mainly stochastic colonisation. These results, and those from an analogous study carried out on Papilionoidea, point to Hesperioidea having (i) overall more impoverished faunas on islands and (ii) being subject to stochastic or historical colonisation events more than Papilionoidea. Species not predicted to occur on islands based on their mainland distributions and ecological traits, are foci for conservation attention. However, as many species becoming extinct on the islands may be irreplaceable, all species, in particular the Sardinian ones, deserve to be conserved.     

Virtual brain endocast of Antifer (Mammalia: Cervidae), an extinct large cervid from South America

A diverse fossil record of Cervidae (Mammalia) has been documented in the South American Pleistocene, when these animals arrived during the Great American Biotic Interchange. Using computed tomography-scanning techniques, it is possible to access the endocranial morphology of extinct species. Here, we studied the brain endocast of the extinct late Pleistocene cervid Antifer ensenadensis from southern Brazil, one of the largest forms that lived on this continent, using comparative morphology, geometric morphometrics, and encephalization quotients. The analyzed endocasts demonstrate that A. ensenadensis had a gyrencephalic brain, showing a prominent longitudinal sinus (=sagittal superior sinus), which is also observed in the large South American cervid Blastocerus dichotomus. The encephalization quotient is within the variation of extant cervids, suggesting maintenance of the pattern of encephalization from at least the late Pleistocene. Geometric morphometric analysis suggested a clear and linear allometric trend between brain endocast size and shape, and highlights A. ensenadensis as an extreme form within the analyzed cervids regarding brain morphology.     

Metabolism of thromboxane B2 in the isolated perfused rat kidney: mass spectrometric identification of urinary products

The metabolism of thromboxane B2 (TXB2), the stable breakdown product of thromboxane A2, has been studied in isolated perfused kidney preparations using a recirculating system. In a first experiment, TXB2 was infused at a rate of 20 micrograms/kg per min. In a second experiment, a 1:1 mixture of TXB2 and octadeuterated TXB2 (0.4 microgram/kg per min each) was infused. Urinary samples collected during the infusion of TXB2 or vehicle were extracted on C18 cartridges and derivatized to methyl or pentafluorobenzyl ester, methyloxime, trimethylsilyl ether. Samples were analyzed by high-resolution gas chromatography-mass spectrometry in the electron impact and negative ion chemical ionization modes. Products of beta-oxidation, reduction of the delta 5,6 double bond and dehydrogenation at C-11 (2,3-dinor-TXB2, 2,3-dinor-TXB1, 2,3,4,5-tetranor-TXB1 and 11-dehydro-TXB2) were identified in addition to unmetabolized TXB2. 2,3,4,5-tetranor-TXB1 and 2,3-dinor-TXB1 were the most abundant metabolites.     

Presence of a drifting algal bed in the Mar Piccolo basin,Taranto (Ionian Sea,Southern Italy)

A survey is reported of the drifting algal community in Mar Piccolo, a polluted basin subject to sewage outlets. The key role was played by a few key species, mainly floridean red algae.     

Fecal Microflora in Healthy Persons in a Preindustrial Region

Procedures for quantitating the fecal microflora of man were described. Special attention was given to criteria for characterizing the culturable aerobic, Micro-aerophilic, and anaerobic bacteria. Three groups of healthy persons were studied: wholly breast-fed infants (2 to 4 month-olds), weanlings (1 to 2 year-olds), and adults. In breast-fed children, bifidobacteria predominate and outnumber by one or several logs all other culturable bacteria. The fecal flora of wholly breast-fed infants is "simpler" and more numerous [10(11) to 10(12) per g (wet weight) of feces than that of the adult 10(2) to 10(11) per g]. In the adult, gram-negative anaerobic bacilli (bacteroides) outnumber all other groups by a factor of 1 log or more. Weanlings receiving an adult-type diet, but still breast-fed, showed a flora intermediate between that of the wholly breast-fed infant and that of the adult, but more similar to the latter. Anaerobes always constitute the predominant component of the culturable flora of children and adults and are always found in large numbers under conditions of health. The aerobes are significantly less numerous, and vary widely in their number and in the frequency with which they appear in feces.