A revision of Aceratherium blanfordi Lydekker, 1884 (Mammalia: Rhinocerotidae) from the Early Miocene of Pakistan: postcranials as a key

Rhinocerotids are particularly abundant and diversified in Neogene deposits of the Indian subcontinent, but their systematics is far from being well defined. Based on the revision of old collections and new findings from the Early Miocene of the Bugti Hills and Zinda Pir, Pakistan, ‘Aceratherium blanfordi Lydekker, 1884’ is a chimera, consisting of two dentally convergent but postcranially distinct rhinocerotid taxa: Pleuroceros blanfordi and Mesaceratherium welcommi sp. nov. Postcranial features appear to be much more diagnostic than craniodental morphology in this case. A phylogenetic analysis based on 282 morphological characters scored for 28 taxa (four outgroups and ingroup including both taxa of interest and a ‘branching group’) strengthens this statement and supports Pleuroceros and Mesaceratherium as monophyletic genera within Rhinocerotinae. Both genera are recognized for the first time outside Europe. In the Bugti Hills, P. blanfordi and M. welcommi are part of an exceptionally diversified rhinocerotid fauna, with up to nine species associated in the same locality (Kumbi 4f). This rhinocerotid assemblage confirms the earliest Miocene age (Agenian/Aquitanian) of the upper member of the Chitarwata Formation as a whole. Coeval homotaxic rhinocerotid faunas from Europe (France, Czech Republic) and East Africa (Uganda, Kenya) support broad and sustainable rhinocerotid interchanges amongst South Asia, Europe, and Africa under compatible environmental conditions throughout earliest Miocene times. © 2010 The Linnean Society of London, Zoological Journal of the Linnean Society, 2010, 160 , 139–194.     

Predicting xylem phenology in black spruce under climate warming

In the next century, the boreal ecosystems are projected to experience greater rates of warming than most other regions of the world. As the boreal forest constitutes a reservoir of trees of huge ecological importance and only partially known economic potential, any possible climate‐related change in plant growth and dynamics has to be promptly predicted and evaluated. A model for assessing xylem phenology in black spruce [Picea mariana (Mill.) B.S.P.] using daily temperatures and thermal thresholds was defined and applied to predict changes in onset, ending and duration of xylem growth under different warming scenarios with temperatures rising by up to 3 °C. This was achieved by collecting and analyzing a dataset obtained from a 7‐year monitoring of cambium phenology and wood formation on a weekly time‐scale in trees growing in four sites at different latitudes and altitudes in the Saguenay‐Lac‐Saint‐Jean region (Quebec, Canada). The onset of xylem growth occurred between mid‐May and early June while the end ranged between mid‐September and early October, resulting in a growing season of 101–141 days. The model predicted longer duration of xylem growth at higher temperatures, with an increase of 8–11 days/ °C, because of an earlier onset and later ending of growth. With an increase of 3 °C in the mean temperature during the year, the duration of xylem growth changed on average from 125 to 160 days. The predicted changes in cambial phenology could significantly affect future wood production of the boreal ecosystems.     

Variation of carbon isotope fractionation in hydrogenotrophic methanogenic microbial cultures and environmental samples at different energy status

Methane is a major product of anaerobic degradation of organic matter and an important greenhouse gas. Its stable carbon isotope composition can be used to reveal active methanogenic pathways, if associated isotope fractionation factors are known. To clarify the causes that lead to the wide variation of fractionation factors of methanogenesis from H₂ plus CO₂ (), pure cultures and various cocultures were grown under different thermodynamic conditions. In syntrophic and obligate syntrophic cocultures thriving on different carbohydrate substrates, fermentative bacteria were coupled to three different species of hydrogenotrophic methanogens of the families Methanobacteriaceae and Methanomicrobiaceae. We found that C‐isotope fractionation was correlated to the Gibbs free energy change (ΔG) of CH₄ formation from H₂ plus CO₂ and that the relation can be described by a semi‐Gauss curve. The derived relationship was used to quantify the average ΔG that is available to hydrogenotrophic methanogenic archaea in their habitat, thus avoiding the problems encountered with measurement of low H₂ concentrations on a microscale. Boreal peat, rice field soil, and rumen fluid, which represent major sources of atmospheric CH₄, exhibited increasingly smaller , indicating that thermodynamic conditions for hydrogenotrophic methanogens became increasingly more favourable. Vice versa, we hypothesize that environments with similar energetic conditions will also exhibit similar isotope fractionation. Our results, thus, provide a mechanistic constraint for modelling the ¹³C flux from microbial sources of atmospheric CH₄.     

In Vitro Production of Metacyclic Forms of Trypanosoma musculi and Their Infectivity in CBA Mice1

ABSTRACT. Bloodstream forms of Trypanosoma musculi, cultured in Schneider's drosophila medium at room temperature, multiply and differentiate through a series of developmental stages into infective metacyclic trypomastigotes in 10 days. Oral inoculation with these culture forms into CBA mice produced a parasitemia similar to that produced by intraperitoneal infection with bloodstream forms except for a three-day longer prepatent period. Attempts to induce parasitemia with bloodstream forms given orally were unsuccessful.     

Hidden diversity and endemism on seamounts: focus on poorly dispersive neogastropods

The seamounts chain offers a set of fragmented habitats in which species with poor dispersive ability may undergo divergence in allopatry. Such a scenario may explain the endemism often described on seamounts. In gastropods, it is possible to infer the mode of development of a species from the morphology of its larval shell. Accordingly, we examine the population genetics of several caenogastropods from the Norfolk and Lord Howe seamounts (south‐west Pacific) with contrasting modes of larval development. A prerequisite to our study was to clarify the taxonomic framework. The species delimitation was ruled using an integrative approach, based on both morphological and molecular evidence. Molecular data indicate an unexpected taxonomic diversity within the existing species names. Both the clarification of the taxonomic framework and the importance of the sampling effort allow us to confidently detect cryptic diversity and micro‐endemism. These results are discussed in relation to the dispersive capacities of the organisms. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100 , 420–438.     

Global change and root function

Global change includes land-use change, elevated CO₂ concentrations, increased temperature and increased rainfall variability. All four aspects by themselves and in combination will influence the role of roots in linking below- and above-ground ecosystem function via organic and inorganic resource flows. Root-mediated ecosystem functions which may be modified by global change include below-ground resource (water, nutrients) capture, creation and exploitation of spatial heterogeneity, buffering of temporal variations in above-ground factors, supply and storage of C and nutrients to the below-ground ecosystem, mobilization of nutrients and C from stored soil reserves, and gas exchange between soil and atmosphere including the emission from soil of greenhouse gases. The theory of a functional equilibrium between root and shoot allocation is used to explore predicted responses to elevated CO₂ in relation to water or nutrient supply as limiting root function. The theory predicts no change in root:shoot allocation where water uptake is the limiting root function, but substantial shifts where nutrient uptake is (or becomes) the limiting function. Root turnover will not likely be influenced by elevated CO₂, but by changes in regularity of water supply. A number of possible mechanisms for root-mediated N mineralization is discussed in the light of climate change factors. Rhizovory (root consumption) may increase under global change as the balance between plant chemical defense and adapted root consuming organisms may be modified during biome shifts in response to climate change. Root-mediated gas exchange allows oxygen to penetrate into soils and methane (CH₄) to escape from wetland soils of tundra ecosystems as well as tropical rice production systems. The effect on net greenhouse gas emissions of biome shifts (fens replacing bogs) as well as of agricultural land management will depend partly on aerenchyma in roots.     

Ruffed Grouse Winter Habitat Use in Mixed Softwood-Hardwood Forests,Québec,Canada

Abstract: Ruffed grouse (Bonasa umbellus) is a popular small game species in northeastern North America. We assessed female ruffed grouse habitat characteristics during winter of 2001-2002 and 2002-2003 in a region dominated by mixed softwood-hardwood forests by comparing used and random locations. We followed 23 radiotagged adult females in 2 forest sites of the Réserve faunique de Portneuf, Québec, Canada, from late November to mid-April. We described grouse habitat using ground surveys and identified selected habitat characteristics using analysis of variance and logistic regression. Females preferred mixed softwood-hardwood stands > 17 m tall and 61-120 years old. Compared with random locations, grouse locations had more well-developed total canopy cover (>4m;75%), canopy (>4m;35%), midstory (1-4 m tall; 35%), and lower-story (<1 m tall; 23%) coniferous cover, and higher coniferous stem density and tree basal area (dbh > 9 cm; 343 stems/ha and 9.0 m²/ha, respectively). Forest management should maintain mature mixed softwood-hardwood stands (50% coniferous), which are adequate winter habitat for ruffed grouse.