Effects of age,territoriality and breeding on survival of Bonelli’s Eagle Aquila fasciata

Survival typically contributes most to population trends in long‐lived birds and its accurate estimation is therefore vital for population management and conservation. We evaluated the effects of age, territoriality and reproduction on survival in Bonelli’s Eagle Aquila fasciata through multistate capture‐mark‐recapture analyses on a long‐term dataset. Monitoring was carried out in southeast France (1990–2008) and involved the surveying of territorial Eagles, the marking of fledged chicks, and the recording of resightings and recoveries of marked non‐territorial and territorial birds. Survival improved with age, but territoriality was not retained in the best model; yearly survival was estimated at 0.479 for fledglings (to 1 year of age), 0.570 for 1‐ and 2‐year‐olds, and 0.870 for 3‐year‐old and older individuals. The second best model supported a further increase in survival from 3‐year‐olds (0.821) to older individuals (0.880). In the third best supported model, territoriality enhanced survival, but only in 2‐year‐olds (0.632 vs. 0.562 for non‐territorial). We found no correlation between the previous breeding stage and future survival, consistent with the long lifespan of the study species. Nevertheless, 4‐year‐old and older successful breeders were more likely to breed the following year than failed adult breeders (0.869 vs. 0.582), suggesting that the cost of reproduction is small in comparison with the variation in quality among individuals or their territories.     

Global decomposition experiment shows soil animal impacts on decomposition are climate‐dependent

Climate and litter quality are primary drivers of terrestrial decomposition and, based on evidence from multisite experiments at regional and global scales, are universally factored into global decomposition models. In contrast, soil animals are considered key regulators of decomposition at local scales but their role at larger scales is unresolved. Soil animals are consequently excluded from global models of organic mineralization processes. Incomplete assessment of the roles of soil animals stems from the difficulties of manipulating invertebrate animals experimentally across large geographic gradients. This is compounded by deficient or inconsistent taxonomy. We report a global decomposition experiment to assess the importance of soil animals in C mineralization, in which a common grass litter substrate was exposed to natural decomposition in either control or reduced animal treatments across 30 sites distributed from 43°S to 68°N on six continents. Animals in the mesofaunal size range were recovered from the litter by Tullgren extraction and identified to common specifications, mostly at the ordinal level. The design of the trials enabled faunal contribution to be evaluated against abiotic parameters between sites. Soil animals increase decomposition rates in temperate and wet tropical climates, but have neutral effects where temperature or moisture constrain biological activity. Our findings highlight that faunal influences on decomposition are dependent on prevailing climatic conditions. We conclude that (1) inclusion of soil animals will improve the predictive capabilities of region‐ or biome‐scale decomposition models, (2) soil animal influences on decomposition are important at the regional scale when attempting to predict global change scenarios, and (3) the statistical relationship between decomposition rates and climate, at the global scale, is robust against changes in soil faunal abundance and diversity.     

An Ex Vivo Study of Congenital Pigmented Nevi in Epidermal Reconstructs

In order to study morphologic and functional characteristics of pigment cells in congenital pigmented nevi, autologous or heterologous reconstructs have been made using normal keratinocytes and nevus cells from the dermal-epidermal junction or from the dermis. All these cells, keratinocytes and nevus cells, were used as cell suspensions immediately after dissociation from the tissues or after subsequent brief cultivation in a serum-free medium. Reconstructed epidermis were cultured for 15 days at the air-liquid interface with or without ultraviolet (UV) B exposure. The reconstructs were examined macroscopically (formation of hyperpigmented macules), histologically (pigment cell nesting) and ultrastructurally (pigment structure and transfer). Typical nesting of nevus cells was observed in the dermal-epidermal junction or in the superficial dermis associated with macroscopically detectable small pigmented macules. UVB exposure induced an upward migration of nevus cells in the suprabasal layers of the epidermis. This tissue model can be considered as an excellent system for the ex vivo reproduction of pigmented nevi and as an assay of the sensitivity of nevus cells towards UVB irradiation.     

Evolutionary significance of oral morphology in the carnivorous tadpoles of tiger frogs, genus Hoplobatrachus (Ranidae)

We describe the larval stages of three species of the Asian-African tiger frogs Hoplobatrachus chinensis, H. occipitalis and H. tigerinus . The tadpoles of all three species are very similar, with peculiar oral features: (1) double rows of needle-like labial teeth, (2) strong emarginations on the large jaw sheaths and (3) keratinized spurs on the buccal floor. Characters 1 and 2 (and perhaps 3) are probably related to the carnivorous habits of these tadpoles. A molecular phylogeny based on 2430 base pairs of two nuclear and four mitochondrial genes corroborated monophyly of Asian and African Hoplobatrachus, and identified Euphlyctis as their sister group. Tadpoles of the latter genus lack buccal spurs and double labial tooth rows but share large jaw sheaths, the upper with a medial projection. Therefore, the common ancestor of Euphlyctis and Hoplobatrachus probably was also characterized by this state, and may have been facultatively carnivorous. Further carnivorous specializations in Hoplobatrachus could explain why tiger frogs have been so successful in populating arid environments where ponds are at high risk of desiccation. Larval morphology may prove to be the key innovation which enabled them to disperse, in the Late Cenozoic, into their current very wide distribution area in Asia and Africa.  © 2004 The Linnean Society of London, Biological Journal of the Linnean Society , 2004, 81 , 171–181.     

Adenosine Triphosphatases Bound to Plasmalemma, Mitochondria, and Microsomes or Present in the Cytoplasmic Phase from Potato Tubers

Between pH 4–10, basal ATPase activity, measured in the absence of mineral ions, was 10 to 100 times higher in the final cytoplasmic supernatant from potato tuber homogenates than in the membraneous fractions (purified plasmalemma, purified mitochondria and microsomes). The soluble ATPase was slightly inhibited, whereas the membrane-bound ATPases were all stimulated by Mg²⁺ ions. A further stimulation by Na⁺ or K⁺ ions was only observed in purified plasmalemma or mitochondria, at alkaline pH (7.5–9.5). At a fixed (Na⁺+ K⁺) concentrations (80 mM), this last stimulation was much greater in purified mitochondria (350%) than in plasmalemma (33%); it also increased with (Na⁺+ K⁺) concentrations up to 200 mM in mitochondria whereas, in plasmalemma, it was roughly constant for monovalent ion concentrations between 20 and 200 mM. General properties of the plasma membrane-bound ATPase have been determined, i.e. substrate specificity, activity variations with quantity of substrate, temperature, pH, etc. Divalent cations stimulated strongly the ATPase in the following order: Mn²⁺ > Mg²⁺ > Ca²⁺. The maximum ATP hydrolysis velocity for that part of ATPase activity which is strictly dependent on Mg²⁺ ions was 3.85 μmol × mg^?1 protein × h^?1. This plasma membrane ATPase was not sensitive to ouabaïn or to oligomycin.     

Cytokinins and Morphological Aspects of French-bean Roots in the Presence of Rhizobium

Typical abnormalities were observed on French-bean roots when the plants were cultivated in the presence of Rhizobium phaseoli, under hydroponic conditions. Substantial quantities of cytokinins were detected in the plant culture medium and their concentration remained high until the 9th day after inoculation, when the first nodules appeared. The presence of both partners, plant and bacteria, was required for this synthesis. Exogenous cytokinin production was responsible for morphological alterations of the roots observed before nodulation.     

Relations polyphenols-croissance: Lignification et limitation de croissance chez Lycopersicum esculentum

Abstract Polyphenols and growth – Lignification and limitation of growth in Lycopersicum esculentum. When fed with quinic acid, young tomato seedlings (Lycopersicum esculentum Mill. cv. St. Pierre) exhibited reduced growth and marked changes in cell wall composition: cellulose concentrations decreased whereas those of lignin increased. Exogenously supplied growth substances (IAA, GA₃) affected both the size of the plants and the lignification process: IAA treatments resembled quinic acid induced modifications with regard to both size and lignification: GA₃ applied to quinate treated plants counteracted the effects of this compound by reducing the lignin content and improving the growth. The possible effect of abnormal lignification as a limiting factor in cell growth is supported by the characterization of lignins in tissues different from xylem.     

Mechanisms driving the specificity of a myrmecophyte–ant association

In the understory of pristine Guianese forests, the myrmecophyte Hirtella physophora almost exclusively shelters colonies of the plant-ant Allomerus decemarticulatus in its leaf pouches. We experimentally tested three non-mutually exclusive hypotheses concerning phenomena that can determine the species specificity of this association throughout the foundation stage of the colonies: (1) interspecific competition results in the overwhelming presence of A. decemarticulatus queens or incipient colonies; (2) exclusion filters prevent other ant species from entering the leaf pouches; and (3) host-recognition influences the choice of founding queens, especially A. decemarticulatus . Neither interspecific competition, nor the purported exclusion filters that we examined play a major role in maintaining the specificity of this association. Unexpectedly, the plant trichomes lining the domatia appear to serve as construction material during claustral foundation rather than as a filter. Finally, A. decemarticulatus queens are able to identify their host plant from a distance through chemical and/or visual cues, which is rarely demonstrated in studies on obligatory ant–plant associations. We discuss the possibility that this specific host-recognition ability could participate in shaping a compartmentalized plant-ant community where direct competition between ant symbionts is limited.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 97 , 90–97.     

Constraints on evolution of virus avirulence factors predict the durability of corresponding plant resistances

Understanding the factors driving pathogen emergence and re-emergence is a major challenge, particularly in agriculture, where the use of resistant plant cultivars imposes strong selective pressures on plant pathogen populations and leads frequently to 'resistance breakdown'. Presently, durable resistances are only identified after a long period of large-scale cultivation of resistant cultivars. We propose a new predictor of the durability of plant resistance. Because resistance breakdown involves modifications in the avirulence factors of pathogens, we tested for correlations between the evolutionary constraints acting on avirulence factors or their diversity and the durability of the corresponding resistance genes in the case of plant–virus interactions. An analysis performed on 20 virus species–resistance gene combinations revealed that the selective constraints applied on amino acid substitutions in virus avirulence factors correlate with the observed durability of the corresponding resistance genes. On the basis of this result, a model predicting the potential durability of resistance genes as a function of the selective constraints applied on the corresponding avirulence factors is proposed to help breeders to select the most durable resistance genes.