类群取样与系统发育分析精确度之探索

Appropriate and extensive taxon sampling is one of the most important determinants of accurate phylogenetic estimation. In addition, accuracy of inferences about evolutionary processes obtained from phylogenetic analyses is improved significantly by thorough taxon sampling efforts. Many recent efforts to improve phylogenetic estimates have focused instead on increasing sequence length or the number of overall characters in the analysis, and this often does have a beneficial effect on the accuracy of phylogenetic analyses. However, phylogenetic analyses of few taxa (but each represented by many characters) can be subject to strong systematic biases, which in turn produce high measures of repeatability (such as bootstrap proportions) in support of incorrect or misleading phylogenetic results. Thus, it is important for phylogeneticists to consider both the sampling of taxa, as well as the sampling of characters, in designing phylogenetic studies. Taxon sampling also improves estimates of evolutionary parameters derived from phylogenetic trees, and is thus important for improved applications of phylogenetic analyses. Analysis of sensitivity to taxon inclusion, the possible effects of long-branch attraction, and sensitivity of parameter estimation for model-based methods should be a part of any careful and thorough phylogenetic analysis. Furthermore, recent improvements in phylogenetic algorithms and in computational power have removed many constraints on analyzing large, thoroughly sampled data sets. Thorough taxon sampling is thus one of the most practical ways to improve the accuracy of phylogenetic estimates, as well as the accuracy of biological inferences that are based on these phylogenetic trees.     

Techne, Technoscience, and the Circulation of Comestible Commodities: An Introduction

In this "In Focus" introduction, we present the ways in which discourses of techne (craft or artisanship) and technoscience mediate the production, consumption, and circulation of food and drink. The authors in this "In Focus" examine food and drink as localized instances of large-scale spatial and temporal processes and as cultural-material markers of power/knowledge. Our work on the current controversies surrounding foie gras exemplifies how specialty commodities marketed as "artisanal" are simultaneously legitimated through technoscientific practices and invocations of tradition or nature. Claims to distinction based on tradition or "terroir" are also imbricated in global industrial production and distribution.     

2-Trans-Abscisic Acid Biosynthesis and Metabolism of ABA-Aldehyde and Xanthoxin in Wild Type and the aba Mutant of Arabidopsis thaliana

Abscisic acid (ABA) and 2-trans-ABA (t-ABA) biosynthesis werestudied in wild type Landsberg erecta and the three allelicaba mutants of Arabidopsis thaliana (L.) Heynh., which are impairedin epoxy-carotenoid biosynthesis. Labelling experiments with¹⁸O₂and mass spectrometric analysis of [¹⁸O]ABA and its catabolitesABA-glucose ester (ABA-GE) and phaseic acid (PA), and t- ABAand t-ABA-GE, showed that t-ABA biosynthesis was less affectedthan ABA biosynthesis by mutations at the ABA locus. The aba-4allele caused the most severe impairment of ABA biosynthesiscompared with the other two mutant alleles aba-1 and aba-3,yet aba-4 plants synthesized as much t-ABA as wild type Landsbergerecta plants. Feeding experiments with RS- [²H₆]ABA-aldehydeisomers and unlabelled xanthoxin isomers suggest that t-xanthoxinand t-ABA-aldehyde are precursors to ABA and t-ABA in Arabidopsis Key words: ABA-alcohol, ABA-aldehyde, ABA-glucose ester, ¹⁸O₂ labelling, phaseic acid     

The relationship between the ventral nerve cord,body size and phylogeny in ground beetles (Coleoptera: Carabidae)

The ventral nerve cord in the family Carabidae (considered in the widest sense! exhibits variations in the degree of fusion of thoracic and abdominal ganglia. There are usually three discrete thoracic ganglia and between one and seven discrete abdominal ganglia, the number differing between tribes. Of the 44 tribes and 177 species examined, 38 tribes contained species showing no differences in the degree of ventral nerve cord consolidation. However, the remaining six tribes showed variations in the degree of ventral nerve cord consolidation between genera (Lebiini, Cychrini, Nebriini, Scaritini, Licinini and Brachinini), whilst one genus showed variations between species (Leistus, Nebriini). No variation in ventral nerve cord consolidation was observed in conspecifics. The degree of ventral nerve cord consolidation is inversely proportional to overall body length. With respect to phylogeny, the degree of consolidation of the nerve cord docs not consistently support the traditional Carabinae-Harpalinae subfamily division. However, the Harpalinae always have four or less discrete abdominal ganglia (with the sole exception of the Broscinij, whilst the Carabinae exhibit almost the whole range of variations. Thus the Harpalinae (or the major pari of it) may be a monophyletic group, but this is not true of the Carabinae. Trends in the degree of ventral nerve cord consolidation for the various tribes were noted, and phylogenetic implications were evaluated wherever possible.