1,720,976 research outputs found
Pig pigmentation:testing Gloger’s rule
No full textComparative studies indicate that several mammalian clades obey Gloger’s rule in that they exhibit darker coloration in humid warm climates, although the mechanisms responsible for this association still are poorly understood. We surveyed external appearances of a single species, the feral pig (Sus scrofa), shot at 48 hunting lodges across North America and matched these to potential abiotic drivers, namely: relative humidity, temperature, precipitation, and ultraviolet (UV) radiation, and to biotic factors of habitat shade and predation pressure. We found that darker animals occupy locations of greater precipitation and warmer temperatures, as expected from Gloger’s rule. The recent range expansion of S. scrofa implies selection for pelage coloration has occurred very rapidly. Separating pelage coloration into eumelanin- and phaeomelanin-based pigmentation, we found more pronounced eumelanin-based pelage in areas of higher rainfall and temperatures and UV radiation, whereas pelage phaeomelanin is related to cool dry climates with lower UV radiation. This implies that humidity or UV protection but not crypsis are the mechanisms underlying Gloger’s rule in this species and the factors driving eumelanin and phaeomelanin expression in mammalian pelage are different, reinforcing new interpretations of this venerable rule
Anti-predator defence drives parallel morphological evolution in flea beetles
No full text9 páginas.-- Ge, Deyan et al.Complex morphological or functional traits are frequently considered evolutionarily unique and hence useful for taxonomic classification. Flea beetles (Alticinae) are characterized by an extraordinary jumping apparatus in the usually greatly expanded femur of their hind legs that separates them from the related Galerucinae. Here, we examine the evolution of this trait using phylogenetic analysis and a time-calibrated tree from mitochondrial (rrnL and cox1) and nuclear (small subunits and large subunits) genes, as well as morphometrics of femora using elliptic Fourier analysis. The phylogeny strongly supports multiple independent origins of the metafemoral spring and therefore rejects the monophyly of Alticinae, as defined by this trait. Geometric outline analysis of femora shows the great plasticity of this structure and its correlation with the type and diversity of the metafemoral springs. The recognition of convergence in jumping apparatus now resolves the long-standing difficulties of Galerucinae–Alticinae classification, and cautions against the value of trait complexity as a measure of taxonomic significance. The lineage also shows accelerated species diversification rates relative to other leaf beetles, which may be promoted by the same ecological factors that also favour the repeated evolution of jumping as an anti-predation mechanism.Peer reviewe
Fig. 3 in Explaining mammalian abundance and elevational range size with body mass and niche characteristics
No full textFig. 3.—Scatterplots illustrating the relationships between MASS (body mass) and ABD (mean abundance, a–e) and ER (elevational range size, f–j) of small mammals along the Wolong, Luoji, Gongga, Baima Snow, and Sejila gradients. All the three variables were log10(x + 1) transformed. Open circles indicate individual species, and the best fitted line as calculated by linear regression analysis (not accounting for the effects of phylogeny) is shown.Published as part of Wen, Zhixin, Feijó, Anderson, Cheng, Jilong, Du, Yuanbao, Ge, Deyan, Xia, Lin & Yang, Qisen, 2021, Explaining mammalian abundance and elevational range size with body mass and niche characteristics, pp. 13-27 in Journal of Mammalogy 102 (1) on page 20, DOI: 10.1093/jmammal/gyaa093, http://zenodo.org/record/783248
Figure 5 in Phylogeny, taxonomic reassessment and 'ecomorph' relationship of the Orientallactaga sibirica complex (Rodentia: Dipodidae: Allactaginae)
No full textFigure 5. Variation in the shape and principal component analysis of the dorsal and ventral views of the cranium and lateral views of the mandible in voucher specimens. Principal component plots of the dorsal, ventral and mandible cranium are given in (A), (B) and (C), respectively. Canonical variant plots of the dorsal, ventral and mandible cranium are given in (D), (E) and (F), respectively. The data points on these plots are coloured according to the taxonomic status based on the phylogenetic tree. The ellipses give 90% confidence equal frequencies for the four phylogenetic groups.Published as part of Cheng, Jilong, Xia, Lin, Feijó, Anderson, Shenbrot, Georgy I, Wen, Zhixin, Ge, Deyan, Lu, Liang & Yang, Qisen, 2021, Phylogeny, taxonomic reassessment and 'ecomorph' relationship of the Orientallactaga sibirica complex (Rodentia: Dipodidae: Allactaginae), pp. 185-205 in Zoological Journal of the Linnean Society 192 (1) on page 194, DOI: 10.1093/zoolinnean/zlaa102, http://zenodo.org/record/530109
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Variations on the Author
Get PDF“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
Get PDFWe 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
Get PDFWe 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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