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.

     

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.     

Development and characterization of continuous avian cell lines depleted of mitochondrial DNA

Summary Populations of quail and chicken cells were treated with ethidium bromide, an inhibitor of mitochondrial DNA replication. After long-term exposure to the drug, the cell populations were transferred to ethidium bromide (EtdBr)-free medium, and cloned. Clones HCF7 (quail) and DUS-3 (chicken) were propagated for more than a year, and then characterized. Analysis of total cellular DNA extracted from these cells revealed no characteristic mitochondrial DNA molecule by Southern blot hybridization of HindIII- or AvaI-digested total cellular DNA probed with cloned mitochondrial DNA fragments. Reconstruction experiments, where a small number of parental cells was mixed with HCF7 cells and DUS-3 cells before extraction of total cellular DNA, further strengthen the notion that the drug-treated cells are devoid of mitochondrial DNA molecules. The cell populations were found to proliferate at a moderately reduced growth rate as compared to their respective parents, to be auxotrophic for uridine, and to be stably resistant to the growth inhibitory effect of EtdBr and chloramphenicol. At the ultrastructural level, mitochondria were considerably enlarged and there was a severe reduction in the number of cristae within the organelles and loss of cristae orientation. Morphometric analysis revealed a fourfold increase of the mitochondrial profile area along with a twofold decrease of the numerical mitochondrial profiles. Analysis of biochemical parameters indicated that the cells grew with mitochondria devoid of a functional respiratory chain. The activity of the mitochondrial enzyme dihydroorotate dehydrogenase was decreased by 95% and presumably accounted for uridine auxotrophy. This work was supported by a grant from the Medical Research Council of Canada.     

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.     

Alterations in the major heterotrophic bacterial populations isolated from a still bottled mineral water

M orais , P.V. & D a C osta , M.S. 1990. Alterations in the major heterotrophic bacterial populations isolated from a. still bottled mineral water. Journal of Applied Bacteriology 69 , 750–757.
The heterotrophic bacterial population of a bottled mineral water stored in returnable glass bottles and in polyvinyl chloride (PVC) bottles at room temperature was studied over 9–12 months. The plate counts in R₂A medium incubated at 22 and 37C were low initially, increasing to 10⁴-10⁵ cfu/ml within a few days of bottling. The number of bacteria recovered at 22C from PVC bottles was fairly constant during the storage period, but the population isolated at 37C decreased markedly after storage for 1 year. The major components of the population were Pseudomonas strains, one of which was identified as Pseudomonas vesicularis . Major changes took place during storage; two groups of bacteria (B and C) were dominant initially, but during the latter period of storage other groups (F, G and H) increased in number.     

Measurement of nutrient spiralling during a period of continuous surface flow in a Mediterranean temporary stream (Arroyo de La Montesina, Spain)

Uptake rate of calcium, potassium, nitrate-N and phosphorus were measured in a second order Mediterranean temporary stream, in February and March 1992. This study analyzed a period of continuous surface flow between two hydrologic disturbance events (flood and drought) of an annual hydrological cycle (1991–92).The lowest values of uptake length were recorded for nitrate-N in February 92 and calcium in March 92. Nitrate had the highest uptake rate in both release performances, and potassium showed the lowest uptake rate values. The increase of calcium and nitrate uptake rate between February 92 and March 92 suggested a higher ecosystem efficiency in nutrient retention with a higher temperature and light intensity and slower water velocity, discharge and water depth. These results obtained were similar to those reported in permanent streams, indicating that in periods of continuous surface flow (without extreme hydrologic disturbance), abiotic factors can influence nutrient retention in temporary streams.