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CHRISTOPHER J. RAXWORTHY RICHARD G. PEARSON NIRHY RABIBISOA† RY M. RAKOTONDRAZAFY† JEAN-BAPTISTE RAMANAMANJATO† ACHILLE P. RASELIMANANA† SHENGHAI WU‡ RONALD A. NUSSBAUM§ DÁITHÍ A. STONE¶ 《Global Change Biology》2008,14(8):1703-1720
One of the predicted biological responses to climate warming is the upslope displacement of species distributions. In the tropics, because montane assemblages frequently include local endemics that are distributed close to summits, these species may be especially vulnerable to experiencing complete habitat loss from warming. However, there is currently a dearth of information available for tropical regions. Here, we present a preliminary appraisal of this extinction threat using the herpetological assemblage of the Tsaratanana Massif in northern Madagascar (the island's highest massif), which is rich with montane endemism. We present meteorological evidence (individual and combined regional weather station data and reanalysis forecast data) for recent warming in Madagascar, and show that this trend is consistent with recent climate model simulations. Using standard moist adiabatic lapse rates, these observed meteorological warming trends in northern Madagascar predict upslope species displacement of 17–74 m per decade between 1993 and 2003. Over this same period, we also report preliminary data supporting a trend for upslope distribution movements, based on two surveys we completed at Tsaratanana. For 30 species, representing five families of reptiles and amphibians, we found overall mean shifts in elevational midpoint of 19–51 m upslope (mean lower elevation limit 29–114 m; mean upper elevation limit ?8 to 53 m). We also found upslope trends in mean and median elevational observations in seven and six of nine species analysed. Phenological differences between these surveys do not appear to be substantial, but these upslope shifts are consistent with the predictions based on meteorological warming. An elevational range displacement analysis projects complete habitat loss for three species below the 2 °C ‘dangerous’ warming threshold. One of these species is not contracting its distribution, but the other two were not resampled in 2003. A preliminary review of the other massifs in Madagascar indicates potential similar vulnerability to habitat loss and upslope extinction. Consequently, we urgently recommend additional elevational surveys for these and other tropical montane assemblages, which should also include, when possible, the monitoring of local meteorological conditions and habitat change. 相似文献
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TILLY BAKKER-GRUNWALD JEAN-BAPTISTE MARTIN GERARD KLEIN 《The Journal of eukaryotic microbiology》1995,42(4):346-349
ABSTRACT. Trophozoite extracts of axenic Entamoeba histolytica were investigated by natural-abundance 13 C-NMR spectroscopy. The extracts were found to contain a high level of glycogen (30 mM glucose equivalents), which had a compact structure as suggested by α (1 → 6) branch points every 5–6 glucose residues. As other major metabolites, we identified putrescine (9.5 mM) and the following free amino acids: tyrosine and phenylalanine (1 mM), glycine, lysine and methionine (2 mM), isoleucine (5 mM), proline and valine (6–7 mM), leucine (11 mM) and glutamate (22 mM). Glutamate and proline may serve, together with putrescine, as intracellular osmolytes. 相似文献
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JEAN-BAPTISTE MARTIN TILLY BAKKER-GRUNWALD GERARD KLEIN 《The Journal of eukaryotic microbiology》1995,42(2):183-191
ABSTRACT. Phreatamoeba balamuthi is a free-living heterotrophic amoeba that lacks mitochondria. Metabolites of axenically-grown cells were characterized by natural-abundance 13 C-NMR and 31 P-NMR spectroscopy on acellular perchloric acid extracts. The amoebae were found to contain glycogen and trehalose as storage carbohydrates, together with putrescine and several amino acids, most prominently proline; we propose that proline and trehalose may serve in osmoregulation. Glycerophosphocholine and glycerophosphoethanolamine were present with their phosphomonoester derivatives, phosphocholine and phosphoethanolamine. Along with inorganic phosphate, inorganic pyrophosphate, nucleoside diphosphates, nucleoside triphosphates and NAD, P. balamuthi amoebae also contained unusual phosphoinositol diphosphates in large quantities (0.5 μmol/g wet cells). 相似文献
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