Can host‐range allow niche differentiation of invasive polyphagous fruit flies (Diptera: Tephritidae) in La Réunion?

Abstract.  1. Biological invasions bring together formerly isolated insect taxa and allow the study of ecological interactions between species with no coevolutionary history. Among polyphagous insects, such species may competitively exclude each other unless some form of niche partitioning allows them to coexist.
2. In the present study, we investigate whether the ability to exploit different fruits can increase the likelihood of coexistence of four species of polyphagous Tephritidae, one endemic and three successive invaders, in the island of La Réunion. In the laboratory, we studied the performances of all four species on the four most abundant fruit resources in the island, as well as the relative abundances of fly species on these four fruit species in the field. We observe no indication of niche partitioning for any of the four abundant fruits.
3. Analyses of an extensive field data series suggest that: (i) the four fly species largely overlap in fruit exploitation, once climatic effects are accounted for; (ii) however, one species ( Ceratitis capitata ) can exploit rare fruit species that are not exploited by others present in the same climatic niche; and (iii) the endemic species C. catoirii , now nearly extinct in La Réunion, has no private niche with respect to either climatic range or fruit use.
4. On the whole, with the possible exception of C. capitata , the results point to a limited role of fruit diversity in encouraging coexistence among polyphagous tephritids recently brought into contact by accidental introductions.     

Metabolomics reveals herbivore‐induced metabolites of resistance and susceptibility in maize leaves and roots

Plants respond to herbivory by reprogramming their metabolism. Most research in this context has focused on locally induced compounds that function as toxins or feeding deterrents. We developed an ultra‐high‐pressure liquid chromatography time‐of‐flight mass spectrometry (UHPLC‐TOF‐MS)‐based metabolomics approach to evaluate local and systemic herbivore‐induced changes in maize leaves, sap, roots and root exudates without any prior assumptions about their function. Thirty‐two differentially regulated compounds were identified from Spodoptera littoralis‐infested maize seedlings and isolated for structure assignment by microflow nuclear magnetic resonance (CapNMR). Nine compounds were quantified by a high throughput direct nano‐infusion tandem mass spectrometry/mass spectrometry (MS/MS) method. Leaf infestation led to a marked local increase of 1,3‐benzoxazin‐4‐ones, phospholipids, N‐hydroxycinnamoyltyramines, azealic acid and tryptophan. Only few changes were found in the root metabolome, but 1,3‐benzoxazin‐4‐ones increased in the vascular sap and root exudates. The role of N‐hydroxycinnamoyltyramines in plant–herbivore interactions is unknown, and we therefore tested the effect of the dominating p‐coumaroyltyramine on S. littoralis. Unexpectedly, p‐coumaroyltyramine was metabolized by the larvae and increased larval growth, possibly by providing additional nitrogen to the insect. Taken together, this study illustrates that herbivore attack leads to the induction of metabolites that can have contrasting effects on herbivore resistance in the leaves and roots.     

Impacts of climate change on the seasonal distribution of migratory caribou

Arctic ecosystems are especially vulnerable to global climate change as temperature and precipitation regimes are altered. An ecologically and socially highly important northern terrestrial species that may be impacted by climate change is the caribou, Rangifer tarandus . We predicted the current and potential future occurrence of two migratory herds of caribou [Rivière George herd (RG) and Rivière-aux-Feuilles (RAF) herd] under a Canadian General Circulation Model climate change scenario, across all seasons in the Québec–Labrador peninsula, using climatic and habitat predictor variables. Argos satellite-tracking collars have been deployed on 213 caribou between 1988 and 2003 with locations recorded every 4–5 days. In addition, we assembled a database of climate (temperature, precipitation, snowfall, timing and length of growing season) and habitat data obtained from the SPOT VEGETATION satellite sensor. Logistic regression models indicated that both climatic and physical habitat variables were significant predictors of current migratory caribou occurrence. Migratory caribou appeared to prefer regions with higher snowfall and lichen availability in the fall and winter. In the summer, caribou preferred cooler areas likely corresponding to a lower prevalence of insects, and they avoided disturbed and recently burnt areas. Climate change projections using climate data predicted an increased range for the RAF herd and decreased range for the RG herd during 2040–2069, limiting the herds to northeastern regions of the Québec–Labrador peninsula. Direct and indirect consequences of climate change on these migratory caribou herds possibly include alteration in habitat use, migration patterns, foraging behaviour, and demography, in addition to social and economic stress to arctic and subarctic native human populations.     

Pneumocystis carinii and Pneumocystis wakefieldiae in Wild Rattus norvegicus Trapped in Thailand

ABSTRACT. This work reports for the first time the presence of two Pneumocystis species in wild Rattus norvegicus specimens from Thailand. Pneumocystis DNA was detected in 57.7% (15/26) wild rats without apparent association with typical pneumocystosis. Pneumocystis carinii was found alone in five rats (19.2%), Pneumocystis wakefieldiae was detected alone in six rats (23.1%), and two rats were infected by both species (7.7%). In addition, a new P. wakefieldiae variant sequence has been identified in three wild R. norvegicus specimens caught in the same geographical area. The high frequency of Pneumocystis in wild rats documented in this study and the apparent scarcity of severe pneumocystosis were consistent with an efficient circulation of rat Pneumocystis species in ecosystems.     

Functional changes in the control of carbon fluxes after 3 years of increased drought in a Mediterranean evergreen forest?

Our objective was to test how a long‐term increased water limitation affects structural and functional properties of a Mediterranean ecosystem, and how these changes modify the response of the main carbon fluxes to climatic controls. In 2003, a 27% throughfall exclusion experiment was installed in a Quercus ilex L. forest in France. Gross primary production (GPP), ecosystem respiration (R_ECO) and net ecosystem exchange (NEE) were estimated in a control and a dry treatment. Decreasing throughfall decreased GPP by 14% and had a smaller effect on R_ECO (?12%), especially soil respiration R_S (?11%). Interannual variability of GPP (29%) was higher than for R_ECO (12%). Error propagation was used to estimates uncertainties in the NEE fluxes, which ranged from 3% to 10% in the control treatment but up to 167% for NEE in the dry treatment because more steps and data types were involved in the scaling. After 3 years of throughfall exclusion, we found no acclimation of R_S to climatic drivers. Functional properties of the response of R_S to soil water, temperature and rain pulse remained similar in the control and the dry treatments. A diurnal clockwise hysteresis in R_S was probably controlled by canopy photosynthesis with a 3 h lag. The proportion of diurnal variation of respiration due to photosynthesis was similar in all treatments (4–5%). Because of the characteristic of rain in Mediterranean climates, a continuous decrease of water input in these environments have an effect on topsoil water and consequently on R_S only during short periods when rainfall is characterized by infrequent and small events that does not allow the topsoil to reach field capacity and does not allow to dry completely. However, in the longer term, we expect a stronger decrease in R_S in the dry treatment driven by the decrease in GPP.     

Ion-Exchange Properties of Isolated Cell Walls of Brown Algae: The Interstitial Solution

Kloareg, B., Demarty, M. and Mabeau, S. 1987. Ion-exchange propertiesof isolated cell walls of brown algae: the interstitial solution.—J.exp. Bot. 38: 1652–1662. Isolated cell walls of Pelvetia canaliculata (Dene) et Thur.,Laminaria digitata (L.) and other intertidal brown algae wereequilibrated in seawater and various mixtures of sodium andcalcium chlorides. After elution with distilled water, the interstitialsolution was assayed for ionic composition. With respect tothe external solution, it was less concentrated and containedlower proportions of divalent cations. Such modifications wererelated to the divalent ionic fraction and the total anion concentrationof the external solution. No significant differences were foundamong the brown algae investigated in spite of the differingcomposition of their walls. Results were analysed accordingto the polyelectrolyte condensation model. When the concentrationof the external solution was high (1000 meq dm³), experimentaldata were qualitatively in good agreement with the predictionsof the model. Key words: Cell walls, ion-exchange, Phaeophyta.     

zpl, a new gene in drosophila required for neurogenesis

zpl(zip-like) gene mutant embryos showed the cuticular defect with alternative denticle rows and a hole from head to abdomen.zpl mutants also caused the overgrowth of neural cells and axons both in CNS and PNS as well as the wrong pathway of neural fasciculation and the disappearance of hypophysis,as shown by whole mount embryos stained with antibody against HRP and MAb-22C10.Genetic analysis has provided evidence that zpl,located in the right arm of the second chromosome(between 75 and 102 genetic map units),is a new gene closely related to the zip gene.     

Gilianelles: Late Cretaceous microproblematica from Europe and Central America

Abstract: During the last two decades, a range of microfossils have been collected from strata of Late Cretaceous (Coniacian–Maastrichtian) age. The name gilianelles has been coined to accommodate these microproblematica. On the basis of many thousands of specimens, typical features of this group have now been assessed. Distinctive traits are calcareous unilocular, basically axially symmetrical test, in the size range 80–200 μm, with a single‐layered wall of radially arranged crystals, 15 μm thick, the outer surface with a crochet‐like nanostructure, a small‐sized aperture (one tenth of test diameter), situated on the upper surface in vivo. Secondary criteria include modification of axial test symmetry into radial or bilateral symmetry, development of expansions, either spiny or laminar and presence of longitudinal and latitudinal ornament. To date, 60 taxa have been described from northern Spain to northern Germany and from Central America. Evolutionary patterns of gilianelles are diverse, with both short‐ and long‐ranging forms, some of which comprise lineages that were affected by a marked crisis dated at about 73 Ma. This event is here illustrated by the tribe Coraliellini, of which a key taxon, Coraliella cognatio, is described as new. Previous interpretations of Gilianelles as dinoflagellate cysts are discussed and rejected.     

Disentangling Natural From Hunting Mortality in an Intensively Hunted Wild Boar Population

Abstract We assessed age-specific natural mortality (i.e., excluding hunting mortality) and hunting mortality of 1,175 male and 1,076 female wild boar (Sus scrofa) from Chǎteauvillain-Arc en Barrois (eastern France), using a 22-year dataset (1982–2004) and mark-recapture-recovery methods. Overall yearly mortality was >50% for all sex and age-classes. Low survival was mostly due to high hunting mortality; a wild boar had a >40% of chance of being harvested annually, and this risk was as high as 70% for adult males. Natural mortality rates of wild boar were similar for males and females (approx. 0.15). These rates were comparable to rates typical of male ungulates but high for female ungulates. Wild boar survival did not vary across sex and age-classes. Despite high hunting mortality, we did not detect evidence of compensatory mortality. Whereas natural mortality for males was constant over time, female mortality varied annually, independent of fluctuations in mast availability. Female wild boar survival patterns differed from those reported in other ungulates, with high and variable natural mortality. In other ungulates, natural mortality is typically low and stable across a wide range of environmental conditions. These differences may partly reflect high litter sizes for wild boar, which carries high energetic costs. High hunting mortality may induce a high investment of females in reproduction early in life, at the detriment to survival. Despite high hunting mortality, the study population increased. Effective population control of wild boar should target a high harvest rate of piglets and reproductive females.     

Multiple mating and supercoloniality in Cataglyphis desert ants

In social organisms, the breeding system corresponds to the number of breeders in a group, their genetic relationships, and the distribution of reproduction among them. Recent, genetically based studies suggest an amazing array of breeding system and reproductive strategies in desert ants of the genus Cataglyphis. Using highly polymorphic DNA microsatellites, we performed a detailed analysis of the breeding system and population genetic structure of two Cataglyphis species belonging to the same phylogenetic group: C. niger and C. savignyi. Our results show that both species present very different breeding systems. C. savignyi colonies are headed by a single queen and populations are multicolonial. Remarkably, queens show one of the highest mating frequency reported in ants (M_p = 9.25). Workers can reproduce by both arrhenotokous and thelytokous parthenogenesis. By contrast, colonies of C. niger are headed by several, multiply mated queens (M_p = 5.17), and they are organized in supercolonial populations made of numerous interconnected nests. Workers lay arrhenotokous eggs only. These results illustrate the high variability in the socio‐genetic organization that evolved in desert ants of the genus Cataglyphis. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 104 , 866–876.