1,720,961 research outputs found
Conservation genetics of the yellow-bellied toad (Bombina variegata): population structure, genetic diversity and landscape effects in an endangered amphibian
No full textAbstract Revealing patterns of genetic diversity and barriers for gene flow are key points for successful conservation in endangered species. Methods based on molecular markers are also often used to delineate conservation units such as evolutionary significant units and management units. Here we combine phylo-geographic analyses (based on mt DNA) with population and landscape genetic analyses (based on microsatellites) for the endangered yellow-bellied toad Bombina variegata over a wide distribution range in Germany. Our analyses show that two genetic clusters are present in the study area, a northern and a southern/central one, but that these clusters are not deeply divergent. The genetic data suggest high fragmentation among toad occurrences and consequently low genetic diversity. Genetic diversity and genetic connectivity showed a negative relationship with road densities and urban areas surrounding toad occurrences, indicating that these landscape features act as barriers to gene flow. To preserve a maximum of genetic diversity, we recommend considering both genetic clusters as management units, and to increase gene flow among toad occurrences with the aim of restoring and protecting functional meta-populations within each of the clusters. Several isolated populations with especially low genetic diversity and signs of inbreeding need particular short-term conservation attention to avoid extinction. We also recommend to allow natural gene flow between both clusters but not to use individuals from one cluster for translocation or reintroduction into the other. Our results underscore the utility of molecular tools for species conservation, highlight outcomes of habitat fragmentation onto the genetic structure of an endangered amphibian and reveal particularly threatened populations in need for urgent conservation efforts
Detecting tail biters by monitoring pig screams in weaning pigs
No full textAbstract
Early identification of tail biting and intervention are necessary to reduce tail lesions and their impact on animal health and welfare. Removal of biters has become an effective intervention strategy, but finding them can be difficult and time-consuming. The aim of this study was to investigate whether tail biting and, in particular, individual biters could be identified by detecting pig screams in audio recordings. The study included 288 undocked weaner pigs housed in six pens in two batches. Once a tail biter (n = 7) was identified by visual inspection in the stable and removed by the farm staff, the previous days of video and audio recordings were analyzed for pig screams (sudden increase in loudness with frequencies above 1 kHz) and tail biting events until no biting before the removal was observed anymore. In total, 2893 screams were detected in four pens where tail biting occurred. Of these screams, 52.9% were caused by tail biting in the observed pen, 25.6% originated from other pens, 8.8% were not assignable, and 12.7% occurred due to other reasons. In case of a tail biting event, screams were assigned individually to biter and victim pigs. Based on the audio analysis, biters were identified between one and nine days prior to their removal from the pen after visual inspection. Screams were detected earlier than the increase in hanging tails and could therefore be favored as an early warning indicator. Analyzing animal vocalization has potential for monitoring and early detection of tail biting events. In combination with individual marks and automatic analysis algorithms, biters could be identified and tail biting efficiently reduced. In this way, biters can be removed earlier to increase animal health and welfare.Federal Ministry of Food and Agriculture 501100005908Stiftung Tierärztliche Hochschule Hannover (TIHO
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Character-based barcoding, a symbiosis and potential successor of traditional taxonomy and modern DNA barcoding
No full textClassic taxonomy is a powerful tool for identifying animals based on morphology but has shown to be problematic on similar looking, cryptic species. A solution to this problem has been found within the bauplan of life, the DNA (deoxyribonucleic acid). DNA is used to create and regulate proteins. The structure of DNA has highly unique sections that are conserved within species, but diverse between species. One particular section, a 648 bp long fragment of the mitochondrial cytochrome c oxidase subunit 1 (CO1) gene, has become a popular barcode for species identification. Here, a new barcoding technique, character-based barcoding more similar to traditional approaches is tested. This thesis investigates whether CO1 is suitable as a single marker (a) or should be complemented by others (b). Performance of distance- and character-based barcoding (c) is evaluated and it is tested whether character-based barcoding can be used to identify cryptic species (d). In the first manuscript, CO1 sequences of endangered turtle species are compared (a). Having a reliable tool for species identification is an important asset in species protection surveillance. Variability within the barcode region is assessed and the utility of both distance- and character-based methods for species identification are evaluated (c). Odonata is an old order rich in species. As many species have evolved in a short time, it was observed that intra- and interspecific variety is overlapping in some sister groups. This observation made Odonata the ideal candidate for testing CO1 (a), ND1 (b), as well as distance- and character-based-barcoding (c) in the second manuscript. Ants are prime examples for high degrees of cryptic biodiversity due to complex population differentiation, hybridization and speciation processes. As combinations of multiple marker regions seemed to be a better approach to barcoding, three markers (CO1, 28S rDNA, rhodopsin) are tested (b) in the third manuscript. A combined, layered approach to character-based barcoding is evaluated and unique diagnostics specific to geolocations are identified (d). The results of all three studies show that combining multiple markers improves identification success. The character-based approach provides better identification in the tested animal groups. This method can be used to estimate presence, absence or frequency of cryptic species
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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