Redalyc.Objective Measurement of Akodon Budini Dorsal Coloration
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Anais da Academia Brasileira de Ciências ISSN: 0001-3765 [email protected] Academia Brasileira de Ciências Brasil SANDOVAL SALINAS, MARÍA L.; SANDOVAL, JOSÉ D.; COLOMBO, ELISA M. Objective measurement of Akodon budini dorsal coloration: methodological concerns Anais da Academia Brasileira de Ciências, vol. 88, núm. 1, 2016, pp. 489-502 Academia Brasileira de Ciências Rio de Janeiro, Brasil Available in: http://www.redalyc.org/articulo.oa?id=32746362006 How to cite Complete issue Scientific Information System More information about this article Network of Scientific Journals from Latin America, the Caribbean, Spain and Portugal Journal's homepage in redalyc.org Non-profit academic project, developed under the open access initiative Anais da Academia Brasileira de Ciências (2016) 88(1 Suppl.): 489-502 (Annals of the Brazilian Academy of Sciences) Printed version ISSN 0001-3765 / Online version ISSN 1678-2690 http://dx.doi.org/10.1590/0001-3765201620150004 www.scielo.br/aabc Objective measurement of Akodon budini dorsal coloration: methodological concerns MARÍA L. SANDOVAL SALINAS1,2, JOSÉ D. SANDOVAL1,3 and ELISA M. COLOMBO1,3 1Instituto de Investigación en Luz, Ambiente y Visión/ILAV, Universidad Nacional de Tucumán/UNT-Consejo Nacional de Investigaciones Científi cas y Técnicas/CONICET, Av. Independencia, 1800, PC4000, Tucumán, Argentina 2Programa de Investigaciones de Biodiversidad Argentina/PIDBA, Facultad de Ciencias Naturales e Instituto Miguel Lillo, UNT, Miguel Lillo 205, PC4000, Tucumán, Argentina 3Departamento de Luminotecnia, Luz y Visión/DLLyV, Facultad de Ciencias Exactas y Tecnología, UNT, Av. Independencia, 1800, PC4000, Tucumán, Argentina Manuscript received on January 8, 2015; accepted for publication on March 13, 2015 ABSTRACT The role of color in taxonomic and systematic studies of several taxa is central. Color data are more valuable if they permit comparisons. We aimed to provide pelage objective color measurements of a series of Akodon budini and to use those color data to test and to quantitatively analyze the infl uence of both the lighting source and the measuring point, in the determination of pelage color of museum skins. We used a spectroradiometer to measure the pelage color at fi ve points over the dorsal midline of 54 Akodon budini museum skins. PCAs and ANOVAs were conducted over the color data. The characteristics of the studied series also allowed us to include and assess the potential effects of some main sources of intra- specifi c variation. Determinations of fur color strongly depend on the lighting source, and therefore it is essential that lighting conditions are controlled during color measurements and then made explicit when communicating the color characterization of particular taxonomic units. Furthermore, color determinations strongly depend on the measuring point, even on the same body area, and therefore it is critical that the color characterization of a taxon includes the variation between different points of the different body parts of the studied specimens. Key words: chromatic coordinates, CIELab color space, lighting source, measuring points, spectroradiometer. INTRODUCTION 2010) and can vary subtly or dramatically between individuals of different species. Description of color Evaluating the variation in the color of mammal is one of the most crucial tasks in taxa descriptions. pelage forms the basis for a broad range of The role of color in taxonomic and systematic research questions. Accordingly, color itself is studies of several taxa is central, as it constitutes often the primary target of museum-based studies. a major tangible feature. Therefore, pelage color Pelage color usually varies to some degree across can be studied for documenting coloration patterns individuals in many species (Davis and Castleberry of a particular species or group of species and for Correspondence to: María Leonor Sandoval Salinas relating this information to several biological, E-mail: [email protected] ecological, and/or environmental features, in order An Acad Bras Cienc (2016) 88 (1 Suppl.) 490 MARÍA L. SANDOVAL SALINAS, JOSÉ D. SANDOVAL and ELISA M. COLOMBO to assess the degree of intra- and/or inter-specifi c address methodological issues concerning the color variation of the studied taxonomic units. measurement of coat color are very few (but see, Small mammal intra-specifi c color variation has for example, the notable study of Sumner and been related to sex (e.g., Davis and Castleberry Mollon 2003). Particularly, the lighting source (i.e., 2010, Rios and Álvarez-Castañeda 2012), age the light under which pelage is observed) and the (e.g., Rios and Álvarez-Castañeda 2012), habitat measuring point (at which specifi c location color is (e.g., Heth et al. 1988, Carraway and Verts 2002, measured) may have a great infl uence in color data Lai et al. 2008, Rios and Álvarez-Castañeda 2012), but this has not been empirically assessed. These and season (e.g., Camargo et al. 2006), among issues, even in very recent, inclusive, and rigorous others factors. Regarding inter-specific color studies of pelage color (such as the study of Linnen variation, pelage color is considered a valuable et al. 2013), are almost never adequately assessed. taxonomic feature in several cases, in which the In contrast, in other fi elds of Biological Sciences, color variation range related to specifi c identity the importance of these issues has already been is a diagnostic marker of the mammal species (or acknowledged (e.g., Ruiz and Pereira 2014). subspecies). On taxonomic and systematic studies, In recent years, the development of improved coat color is considered a diagnostic feature devices that measure specifi c properties of refl ected to identify several species of mammals (Caro light (such as colorimeters, imagers devices, and 2005). Many descriptions of original species and spectroradiometers) (Lozano 1978, Schanda 1997, subspecies relied heavily on coloration to separate Capilla et al. 2002) allows recording the specifi c groups, and some very recent works deal with color characteristics of the light directly from the variation associated with different taxonomic units object under study (Grill and Rush 2000). These (e.g., Kamilar and Bradley 2011, Singaravelan devices have increasingly been used to quantify et al. 2013). Consequently, pelage coloration has tiny variation in integument color across many received a lot of scientifi c attention for the purpose animal species (Kilner 1997, Goda and Fujii 1998, of grouping taxa. Therefore, considering the variety of questions Villafuerte and Negro 1998, Gerald et al. 2001, that can be answered by studying pelage color, Losey 2003, Davis et al. 2007, Davis and Grayson it is important to consider some methodological 2007, Stevens et al. 2007, Kause et al. 2008, Sezer issues related to the collection and subsequent and Tekelioglu 2009) largely because quantitative interpretation of the color data. This means that only output values enable the realization of detailed a correct description of color could provide useful statistical analyses (Patten and Unitt 2002). information. For example, Davis and Castleberry The main goal of this study was to improve (2010) and Davis et al. (2013) have stated that the currently used methodologies for the collection storage time needs to be considered in studies of color data from small mammal museum skins. of pelage color. Regarding color data collection, Specifi cally, we intend: data are more valuable if they permit comparisons 1. To provide pelage objective color measure- between those obtained by different researchers, ments of a series of Akodon budini. or by the same researcher but in different temporal 2. To use those color data to test and to quantita- (e.g., different days, months or even years) or tively analyze the infl uence of: spatial (e.g., different museums or even different a- The use of different lighting sources. rooms in a museum) conditions, but this issue b- The measurement at different measuring points, has not been suffi ciently studied. The studies that even on the same body area of a specimen. An Acad Bras Cienc (2016) 88 (1 Suppl.) ABOUT MEASURING Akodon budini DORSAL PELAGE COLOR 491 Since spectroradiometry is considered a specimens from a small geographic area (to allow very objective and reliable method for measuring the incorporation of another of the major known color (Zuk and Decruyenaere 1994), we used a sources of intra-specifi c variation of coloration, spectroradiometer to measure the pelage color of i.e., habitat or geographical origin); and, it had to Akodon budini museum skins. The features of the be represented by specimens collected on different studied series allowed us to include and assess the seasons (to allow the incorporation of yet another potential effects of the main sources of intra-specifi c of the major known sources of intra-specific variation (i.e., geographical origin, sex, season, variation of coloration; i.e., collection season, as a sample antiquity, etc.). Because this is the first variable under study). Furthermore, the species had attempt at using these techniques on this species, to be represented by specimens that had all been a secondary goal of this study was to evaluate the prepared and stored in generally the same fashion adequacy of this methodology for future research. and it had to be represented by series of specimens that have been collected more or less regularly for MATERIALS AND METHODS at least the last 25 years (to allow the incorporation HYPOTHESES of sample antiquity as a variable under study). The species that met all the detailed criteria Basically, this study includes two questions: in the Colección Mamíferos Lillo (CML, Facultad 1. How do obtained results vary when measuring de Ciencias Naturales e Instituto Miguel Lillo, with different lighting sources the pelage color Universidad Nacional de Tucumán, Argentina) in specimens of one species of small mammal, was Akodon budini (Cricetidae: Sigmodontinae), Akodon budini? a rodent species that inhabits the Yungas forests 2. How do obtained results vary when measuring of North-western Argentina and South-central at different points the pelage color in specimens Bolivia.