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181.
182.
An apparatus is described for measuring photosynthetic carbondioxide assimilation, dark respiration, photorespiration andthe CO2 compensation point by plant materials fumigated withsulphur dioxide and/or ozone. This system uses an infrared gasanalyser (IRGA) in a closed-loop system. Sulphur dioxide isadded from permeation tubes, and O3 is generated by ultravioletlight. Regulation of fumigant concentration and scrubbing thefumigants from the system are described. Key words: Photosynthesis, Respiration, Atmiospheric Pollution 相似文献
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184.
RAOUL J. MUTTER KEITH DE BLANGER ANDREW G. NEUMAN 《Zoological Journal of the Linnean Society》2007,149(3):309-337
Hybodontoid and nonhybodontoid sharks are described from the Lower Triassic Vega‐Phroso Siltstone Member of Sulphur Mountain Formation on the basis of newly discovered material. The age of the classic fossil site ‘Wapiti Lake’ in the Canadian Rocky Mountains is discussed on the basis of new field data and one conodont found in association. Preliminary results suggest that these elasmobranch remains are between early Smithian and Spathian in age. Apart from the enigmatic genus Listracanthus and previously reported edestoids, the shark fauna consists of at least one hybodont, at least two questionable hybodontoid genera and an elasmobranch of enigmatic affinities, represented by peculiar denticles only and described as ‘genus A’incertae sedis. The presence of the only previously reported hybodont genus, cf. Palaeobates, is erroneous. The largest specimen represents the most complete Early Mesozoic shark known. The heterodonty of its dentition, fin spine morphology and the short, robust body shape imply it represents a member of a new family of shark, Wapitiodidae fam. nov. , and is described here as Wapitiodus aplopagus gen. et sp. nov. The unique dental morphology shows affinities to Polyacrodus but clearly differs in the complete lack of side cusps. Wapitiodus gen. nov. possesses a primitive fin spine structure. The tooth crowns are entirely blunt in the distal (posterior) tooth files, and are acuminate‐unicuspid in several anterior files. Tooth morphology, the shape of the basal cartilages, the proximal insertion of the fin spines and the pectoral fin structure are interpreted as diagnostic characters for this new genus, and possibly for the Wapitiodidae fam. nov. The majority of observed characters appear to be primitive and are reminiscent of Palaeozoic sharks, however, and these features include dorsal fin spine morphology and gross skull anatomy. A second species, provisionally placed in the same genus, is described as Wapitiodus homalorhizo sp. nov. Wapitiodus homalorhizo sp. nov. can be distinguished from W. aplopagus gen. et sp. nov. by the proportions of the fin spines, tooth morphology and possibly the body shape. Several isolated teeth and other fragmentary material are referred to either Wapitiodus gen. nov. sp. indet. or to ?Polyacrodus sp. (Polyacrodontidae gen. et sp. indet.). A third genus of elasmobranch (incertae sedis) is described as ‘Genus A’ and is recognized by its peculiar scales. © 2007 The Linnean Society of London, Zoological Journal of the Linnean Society, 2007, 149 , 309–337. 相似文献
185.
KEITH CHRISTIAN GAVIN BEDFORD BRIAN GREEN ANTHONY GRIFFITHS KEITH NEWGRAIN TIMOTHY SCHULTZ 《Austral ecology》1999,24(2):171-181
Lophognathus temporalis is an arboreal lizard from the wet–dry tropics of Australia. During the wet season the field metabolic rate (FMR) of the lizards was 209 kJ kg?1 d?1, but during the dry season FMR was only 62 kJ kg?1 d?1. Similarly, water flux decreased from 73.6 mL kg?1 d?1 in the wet season to 18.5 mL kg?1 d?1 in the dry season. Body temperatures (Tb) were significantly lower in the dry season, and operative temperatures, calculated by incorporating microclimatic data with characteristics of the lizards, indicated that the seasonal shift was due to changes in thermoregulatory behaviour rather than limitations of the thermal environment. By combining field measurements of Tb and FMR with laboratory measurements of standard metabolic rate over a range of Tb, we were able to subdivide the FMR into its components and to determine which factors contributed to the seasonal reduction in energy expenditure. During the dry season, lizards used 147 kJ kg?1 d?1 less energy than during the wet season, and 24% of this decrease was estimated to be due to the passive effects of lower nighttime Tb, 14% was due to the active selection of lower daytime Tb, 27% was due to the physiological shift to lower standard metabolic rates, and 35% was due to reduced activity in the dry season. Although the population size remained relatively constant (107 lizards ha?1 during the wet season and 125 lizards ha?1 during the dry season), the population structure changed, reflecting the seasonal patterns of recruitment and mortality. The number of lizards active at any one time was much lower in the dry season, reflecting the lower levels of activity in this season. The energy expenditure of the population of L. temporalis was 612 kJ ha?1 d?1 during the wet season and 113 kJ ha?1 d?1 during the dry season. 相似文献
186.
Observations on the chromosomes of nine species ofDahliaCav.(Asteraceae, HeliantheaeCoreopsidinae) show that somehave 2n=32, others 2n=64, with a third group having both chromosomenumbers in the same taxon. Karyotype investigations showed thatthe chromosomes can be divided into groups of 14 metacentricsplus two submetacentrics per set of 16 chromosomes.In situhybridizationusing an rRNA gene probe indicated that the 2n=32 species haveeight hybridization sites whilst the 2n=64 species have 16 sites.Silver nitrate staining of these regions showed that not allof these nucleolar organizers are active. Meiotic analysis atmetaphase I and pachytene, by synaptonemal complex spreading,shows that the 2n=32 species have exclusive bivalent formationwhereas the 2n=64 species have small numbers of univalents plusquadrivalents in addition to bivalents. This study proposesthatDahliaspecies with 2n=32 are allotetraploids whereas thosespecies and chromosome races with 2n=64 are their autopolyploidderivatives. We suggest that a bivalent-promoting mechanismin the 2n=32 species may account for their meiotic behaviouras their component genomes appear so similar, and that thismechanism is also responsible for the low number of quadrivalentsin the 2n=64 taxa.Copyright 1998 Annals of Botany Comapny Chromosome pairing,Dahlia, in situhybridization, karyotype analysis, polyploidy, synaptonemal complex analysis 相似文献
187.
KEITH F. LEWIN JOHN NAGY W. ROBERT NETTLES DAVID M. COOLEY ALISTAIR ROGERS † 《Global Change Biology》2009,15(2):388-395
A direct comparison of treatment uniformity and CO2 use of pure and prediluted free-air CO2 enrichment (FACE) systems was conducted in a forest ecosystem. A vertical release pure CO2 fumigation system was superimposed on an existing prediluted CO2 fumigation system and operated on alternate days. The FACE system using prediluted CO2 fumigation technology exhibited less temporal and spatial variability than the pure CO2 fumigation system. The pure CO2 fumigation system tended to over-fumigate the upwind portions of the plot and used 25% more CO2 than the prediluted CO2 fumigation system. The increased CO2 use by the pure CO2 system was exacerbated at low wind speeds. It is not clear if this phenomenon will also be observed in plots with smaller diameters and low-stature vegetation. 相似文献
188.
SHELAH I. MORITA KEITH M. BAYLESS DAVID K. YEATES BRIAN M. WIEGMANN 《Systematic Entomology》2016,41(1):56-72
Horse flies, family Tabanidae, are the most diverse family‐level clade of bloodsucking insects, but their phylogeny has never been thoroughly explored using molecular data. Most adult female Tabanidae feed on nectar and on the blood of various mammals. Traditional horse fly classification tends towards large heterogeneous taxa, which impede much‐needed taxonomic work. To guide renewed efforts in the systematics of horse flies and their relatives, we assembled a dataset of 110 exemplar species using nucleotide data from four genes—mitochondrial CO1, and nuclear 28S, CAD and AATS. All commonly recognized tribes in Tabanidae are represented, along with outgroups in Tabanomorpha. The phylogeny is reconstructed using Bayesian inference, and divergence times are estimated using Bayesian relaxed clock methods with time constraints from tabanid fossils. Our results show Athericidae strongly supported as the lineage most closely related to Tabanidae, and Pangoniinae and Tabaninae as monophyletic lineages. However, Chrysopsinae is nonmonophyletic, with strong support for both a nonmonophyletic Bouvieromyiini and for Rhinomyzini as sister to Tabaninae. Only the tribes Philolichini, Chrysopsini, Rhinomyzini and Haematopotini are recovered as monophyletic, although Scionini is monophyletic with exclusion of the peculiar genus Goniops Aldrich. Mycteromyia Philippi and Adersia Austen, two enigmatic genera sometimes placed in separate family‐level groups, are recovered inside Pangoniini and Chrysopsini, respectively. Several species‐rich genera are not recovered as monophyletic, including Esenbeckia Rondani, Silvius Meigen, Dasybasis Macquart and Tabanus L. Tabanidae likely originated in the Cretaceous, and all major extant groups were present by the early Palaeogene. This newly revised phylogenetic framework for Tabanidae forms the basis for a new assessment of tabanid diversification and provides context for understanding the evolution of trophic specialization in horse flies. 相似文献
189.
190.
DESIGNS TO BALANCE THE EFFECT OF ORDER OF PRESENTATION AND FIRST-ORDER CARRY-OVER EFFECTS IN HALL TESTS 总被引:14,自引:2,他引:12
HALLIDAY J. MACFIE NICHOLAS. BRATCHELL KEITH. GREENHOFF LLOYD V. VALLIS 《Journal of sensory studies》1989,4(2):129-148
The problem of balancing out the effect of order of presentation and the carryover effect of a preceding sample over a series of presentations of the same set of samples is addressed. A series of designs developed by Williams (1949) are used. The method of calculation is given. Tables containing about 50 consumers of each design for presenting from 4 through to 16 samples are given. 相似文献