Objective measurement of Akodon budini dorsal coloration: methodological concerns

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 intraspecifi 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.

The pattern of color change in small mammal museum specimens: is it independent of storage histories given museum-specific conditions?

“…This eumelanin–pheomelanin relative proportions hypothesis may also be the explanation of why the interaction of Antiquity × Point is highly significant for a* and b* color variables (Table 2 ). As we established in our previous work [ 26 ], color determinations strongly depend on the measuring point, even on the same body area. In [ 26 ], for most studied specimens, the values of the variables a* and b* decreased in a neck-rump direction in specimens of the same age: those specimens are naturally redder and yellower to their necks, which may indicate that near their heads, hairs have relatively more pheomelanin.…”

“…As we established in our previous work [ 26 ], color determinations strongly depend on the measuring point, even on the same body area. In [ 26 ], for most studied specimens, the values of the variables a* and b* decreased in a neck-rump direction in specimens of the same age: those specimens are naturally redder and yellower to their necks, which may indicate that near their heads, hairs have relatively more pheomelanin. If this is the case, eumelanin degradation will be more evident near their tails.…”

“…Color data measured in specimens stored for different periods of time are significantly different. We also found significant interactions between sample antiquity and measuring point [ 26 ] (Table 2 ). These results was found for two of the color variables, those that account for chromaticity (a* and b*; Table 2 ).…”

“…We studied the same Akodon budini series previously studied for other purposes [ 25 , 26 ]. For analyses we used skins from 54 adult specimens (Additional file 1 ).…”

“…As we did in our previous studies [ 25 , 26 ] we measured color data (Additional file 2 ) through a Photo Research PR715 spectroradiometer and the SpectraWin 2 software, and inside a diffuse illumination cabin. This instrument measures the sample spectral reflectance.…”