Expression count: a method for calculating morphological dental trait frequencies by using adjustable weighting coefficients with standard ranked scales

Expression count is the term used for a new method of calculating the frequency of a morphological dental trait in a population sample. This method incorporates into a single value the total trait variation expressed in the sample. It has been designed to increase the information content of small samples of dental remains common with archeological recovery.     

Child social ethology and peer relations: a developmental review of methodology and findings

During the last three decades, developmental research has increasingly emphasized the relevance of peer relations in children’s socialization. However, most studies of child development still focus upon individual differences in social status, tacitly neglecting relational constraints inherent in the ecology of the peer group. In contrast, socioethological approaches have stressed that natural groups provide a variety of distinct social roles that may have a differential impact upon individual growth and development. However, ethological analyses have often been limited to aggressive relations and group dominance structures. Comparable studies of affiliative organization have been hampered by the paucity of models for the study of cohesive social structure, only recently having begun to overcome this obstacle. A potential third dimension of preschool peer group ethology, object use, has been relatively neglected in studies of peer relations. However, recent research suggests that object use is a salient and important component of the social world of the young child. This article reviews methodology and recent findings in the area of peer relations and discusses the developmental implications of this work. Received: 8 December 1998 / Received in revised form: 26 March 1999 / Accepted: 31 March 1999     

DNA recovery from ancient tissues: problems and perspectives

The recovery, amplification and sequencing of nucleic acids from ancient smaples opens new possibilities in many different fields, such as anthropology, archeaology, population genetics, animal and plant evolutionary studies, and forensic medicine. The sample processing for DNA extraction and PCR amplification represents the most delicate phase of ancient DNA analysis, with a major impact on the reproducibility and reliability of the results. In this paper some extraction protocols are reviewed and discussed, with particular reference to the removal of the inhibitory substances usually present in extract from ancient tissues. The effect of contamination from extraneous DNA, a possible source of misleading results, is discussed and guidelines to detect and circumvent the problem are given.     

A critique of field methodology for determining fish feeding periodicity

Synopsis Two major criticisms are directed at studies which attempt to determine changes in the feeding intensity of fish in the natural environment over a 24 hour period. A confusing vocabulary in the literature has lead to misinterpretation of data and erroneous conclusions about the diel nature of fish feeding. Workers also tend to conclude that there is variation in stomach content (and by implication feeding rate) over time, without testing observed differences statistically. Large variations in data render such conclusions suspect.This paper attempts to clarify the existing vocabulary by documenting the more commonly used terms and by providing precise definitions of keywords and phrases. A methodology using the analysis of covariance is proposed which establishes statistical criteria upon which more valid inferences about the temporal continuity of fish feeding can be made.Covariant analysis of stomach content data of the longhorn sculpin, Myoxocephalus octodecemspinosus, is used to refute conclusions based on apparent daily feeding activity patterns and exemplifies the need for applying rigorous inferential analysis.     

The Last Breath: A μCT-based method for investigating the tracheal system in Hexapoda

In recent years, μCT-based studies of the insect tracheal system have become an increasingly important area of research. Nevertheless, the methods proposed in previous research for investigating the respiratory system in the three-dimensional space were described and tested based on a relatively small number of specimens. Additionally, the individuals studied in all these cases represented only a single post-embryonic stadium – pupa or imago – of a particular insect species. Therefore, in the current situation it is difficult to predict the reliability and possible limitations of these methods. To address this problem we conducted a methodological study, during which we used 65 individuals representing larvae, pupae and imagines of the mealworm beetle (Tenebrio molitor). In addition to the protocol previously described, which implicated freezing as a killing technique, we also tested a novel one, which was based on ethyl acetate fumigation of the specimens studied. We included step-by-step guides for the manual and semiautomatic approaches in order to facilitate the digital visualization of the tracheal system. Our investigations enabled us to generate multiple models of the tracheal system of all post-embryonic stages of the mealworm beetle. The methods used proved to be minimally invasive, thus allowing for the application of post-scanning manipulations, such as drying with critical point dryer (CPD). This approach enabled us to merge different three-dimensional models into a single picture and analyse the relationship of the tracheal system with other tissues (e.g., muscles, nervous system). We comprehensively discuss the advantages and possible limitations of the tested methods and provide practical suggestions for conducting the analyses on a wider scale. The visualizations presented in this publication are the first three-dimensional models of the respiratory system using a representative of the extremely diverse order Coleoptera.     

An ethnobotanical survey of the Agter–Hantam, Northern Cape Province, South Africa

The use of a rapid appraisal methodology, followed by a new approach that we refer to as the Matrix Method, has revealed a wealth of traditional knowledge on useful plants amongst people of Khoi–San decent in the Agter–Hantam, Calvinia district, Northern Cape Province of South Africa. The data include 14 new species records of useful plants; 20 new vernacular names and 99 new uses for 46 of the plant species, showing that Khoi–San ethnobotany is still incompletely recorded and that there is an urgent need to document this wealth of traditional knowledge before it is lost forever. This article also introduces two new terms — the Ethnobotanical Knowledge Index (EKI), a quantitative measure of a person's knowledge of local plant use (value between 0 and 1), and the Species Popularity Index (SPI), a quantitative measure of the importance or popularity of each species (value between 0 and 1). In the Agter–Hantam, the EKI varied from 0.20 to 0.93 in older people but even young children had EKI values of 0.27. The best known and most popular indigenous useful plants in the Agter–Hantam are Aloe microstigma (a new species record, with a SPI of 0.97), Hoodia gordonii (SPI = 0.94), Microloma sagittatum (0.94), Sutherlandia frutescens (0.92), Quaqua incarnata (0.92) and Galenia africana (0.85). The new quantitative method will allow for direct comparisons of the preservation of traditional plant knowledge and the importance of various plants species in different communities.