The land–atmosphere water flux in the tropics

Tropical vegetation is a major source of global land surface evapotranspiration, and can thus play a major role in global hydrological cycles and global atmospheric circulation. Accurate prediction of tropical evapotranspiration is critical to our understanding of these processes under changing climate. We examined the controls on evapotranspiration in tropical vegetation at 21 pan-tropical eddy covariance sites, conducted a comprehensive and systematic evaluation of 13 evapotranspiration models at these sites, and assessed the ability to scale up model estimates of evapotranspiration for the test region of Amazonia. Net radiation was the strongest determinant of evapotranspiration (mean evaporative fraction was 0.72) and explained 87% of the variance in monthly evapotranspiration across the sites. Vapor pressure deficit was the strongest residual predictor (14%), followed by normalized difference vegetation index (9%), precipitation (6%) and wind speed (4%). The radiation-based evapotranspiration models performed best overall for three reasons: (1) the vegetation was largely decoupled from atmospheric turbulent transfer (calculated from Ω decoupling factor), especially at the wetter sites; (2) the resistance-based models were hindered by difficulty in consistently characterizing canopy (and stomatal) resistance in the highly diverse vegetation; (3) the temperature-based models inadequately captured the variability in tropical evapotranspiration. We evaluated the potential to predict regional evapotranspiration for one test region: Amazonia. We estimated an Amazonia-wide evapotranspiration of 1370 mm yr⁻¹, but this value is dependent on assumptions about energy balance closure for the tropical eddy covariance sites; a lower value (1096 mm yr⁻¹) is considered in discussion on the use of flux data to validate and interpolate models.     

Morphology and phylogeny of Dicellophilus,a centipede genus with a highly disjunct distribution (Chilopoda: Mecistocephalidae)

The centipede genus Dicellophilus Cook, 1896 (Chilopoda: Geophilomorpha: Mecistocephalidae) has been revised by means of a comparative examination of representative specimens of all the species: morphological variation has been documented by means of both light and scanning electronic microscopy, the geographical distribution has been reassessed and updated based on published and new records, and the phyletic relations between the species have been analysed based on morphological evidence. Dicellophilus is confirmed as a highly distinct lineage, supported by synapomorphies in the labrum and in the pattern of coxal organs. Four species are morphologically recognized, each of them occurring in one of three limited, highly disjunct areas in a restricted boreal temperate belt: Dicellophilus carniolensis (C.L. Koch, 1847) is limited to central Europe (central–eastern Alps, Dinarids, Carpathians, and Dobrogea), Dicellophilus pulcher (Kishida, 1928) occurs in Japan (Honshu), and Dicellophilus anomalus (Chamberlin, 1904) and Dicellophilus limatus (Wood, 1862) both occur in the south‐western part of North America (California and Oregon). High support has been found for the following phyletic relationships: (D. carniolensis (D. pulcher (D. anomalus + D. limatus))). Dicellophilus carniolensis is strongly distinct in some autapomorphic traits, including enlarged clypeus and fewer mandibular lamellae, whereas the sister species D. anomalus and D. limatus share some derived features, including an elongated head and associated appendages, longer antennal setae, and stronger forcipular tubercles. The peculiar geographical distribution of Dicellophilus and the historical scenario suggested by the phylogeny are very unusual in respect to the biogeographical patterns known in all other major groups of terrestrial animals. © 2010 The Linnean Society of London, Zoological Journal of the Linnean Society, 2010, 158 , 501–532.     

Increase of Brain Tryptophan caused by Drugs which stimulate Serotonin Synthesis

THE concentrations of tryptophan normally present in the mammalian brain are below the Michaelis constant (K_m) of tryptophan hydroxylase^1,2, suggesting that the rate of serotonin synthesis depends more on the concentration of brain tryptophan than on the amount of enzyme. We wish to report that various treatments which have been shown to increase brain serotonin synthesis also increase the concentration of tryptophan in brain. Conversely, p-chlorophenylalanine (PCPA), which inhibits serotonin synthesis³, decreases tryptophan in brain.     

Identification of the Tubulin Gene Family and Sequence Determination of One β-Tubulin Gene in a Cold-Poikilotherm Protozoan, the Antarctic Ciliate Euplotes focardii

ABSTRACT. Four different tubulin genes were identified in the somatic nucleus (macronucleus) of Euplotes focardii , a strictly coldadapted, Antarctic ciliate: one of 1,800 bp for α-tubulin and three of 2,150, 1,900, and 1,600 bp, respectively, for β -tubulin. Preliminarily analysed for restriction fragment length polymorphisms, these genes showed remarkable differences in organisation from tubulin genes of other ciliates which live in temperate areas and were analysed in parallel with E. focardii. The complete coding sequence of the 1,600 bp β -tubulin gene was then determined and shown to contain unique structural features of potential importance for E. focardii microtubule organization and activity. Of eight unique substitutions detected, seven were concentrated in the large amino terminal domain of the molecule that directly interacts with the carboxy terminal region of α-tubulin for heterodimer formation. Sequence analysis of the cloned gene revealed, in addition, a potential new exception in the use of the genetic code by ciliates. A TAG codon was aligned in correspondence with Trp-21 which is strictly conserved in every tubulin sequence so far determined.     

Competition between the native and the introduced hornets Vespa crabro and Vespa velutina: a comparison of potentially relevant life‐history traits

1. Invasive alien species are a major threat to biodiversity. In addition to predation and parasitism, native species might suffer from competition when invasive alien species occupy a similar ecological niche. 2. This study focused on the potential interspecific interaction between two hornets: the Asian yellow‐legged hornet, Vespa velutina, a high‐concern invasive alien species recently arrived in Europe; and the native European hornet, Vespa crabro. The two species share a similar ecological niche and V. velutina is rapidly expanding across Europe, which suggests that V. crabro might suffer from competition. 3. Under laboratory‐controlled conditions, two life‐history traits that might cause the two species to compete were investigated: (i) the ability of workers to find food sources and their flexibility in exploiting them (through individual food item choice tests and exploration assays); and (ii) the worker resistance to pathogens (through immune challenge tests). 4. The results show that trophic preference of both species highly overlaps, with a marked dietary preference for honeybees compared with other insect prey and non‐prey protein items. No differences were observed in the exploratory behaviour of both species. Finally, constitutive antibacterial activity was greater in workers of the native species than in workers of the invasive hornet. 5. This laboratory study provides a first assessment under controlled conditions of the factors affecting competition between workers of two hornet species and proposes a framework to assess, in wild contexts, the magnitude of the competition and the impact of the introduced V. velutina on the native V. crabro.     

Decline and recovery in otter Lutra lutra populations in Italy

• 1 Changes in otter Lutra lutra distribution in Italy were examined by analysing geographical, historical and survey data.
• 2 As in other European countries, otters declined sharply in Italy during the late 1970s and throughout the 1980s. Between 1985 and 2004 the species became extinct, except for some reintroductions, in northern and most of central Italy while the species appears to have substantially recovered in its southern range. This recovery of the otter population is apparently not due to increased research effort, but reflects a real expansion of range.
• 3 Differences in the degree of range reduction during the second half of the 20th century and in the availability of suitable habitats are probably the major factors that have determined the two opposite trends shown by otter populations in the last 20 years.
• 4 Better knowledge of otter status and distribution is needed for effective conservation management. We suggest that a national survey of the Italian otter population that employs genetic approaches should represent a first step of the national action plan for otter conservation.

     

Spring migratory routes of eight trans-Saharan passerines through the central and western Mediterranean; results from a network of insular and coastal ringing sites

Detailed information on spring migration routes of songbirds across the Mediterranean is still scanty. Results are presented here from a study on the occurrence of eight Palaearctic-African migrants across the western and central Mediterranean based on ringing data collected during the Progetto Piccole Isole, a co-ordinated project based on standardized mist netting at 21 islands and coastal stations. The species were Melodious Warbler Hippolais polyglotta , Icterine Warbler Hippolais icterina, Bonelli's Warbler Phylloscopus bonelli , Wood Warbler Phylloscopus sibilatrix , Pied Flycatcher Ficedula hypoleuca , Collared Flycatcher Ficedula albicollis , Red-backed Shrike Lanius collurio and Woodchat Shrike Lanius senator . Their capture frequencies were expressed as the frequency of each species relative to the total number of migrants ringed at each station in order to correct for differences in capture effort between stations. For most species, the detailed, quantitative results confirmed the scanty information available so far, whereas in the case of Melodious Warbler and Bonelli's Warbler, evidence of undescribed and unexpected migration routes was found. These results suggest that standardized mist netting provides an important method for studying the migratory routes of small birds, in particular for those species which are not frequently ringed in their breeding and wintering grounds.