Common patterns of color change related to sex, season and latitude in small mammals museum specimens

SANDOVAL SALINAS, MARÍA LEONOR; SANDOVAL, JOSÉ DOMINGO; COLOMBO, ELISA MARGARITA; BARQUEZ, RUBÉN MARCOS

Buenos Aires

Congreso; International Colour Association (AIC) Conference 2019; 2019

Grupo Argentino del Color (GAC)

In a recent study, we addressed the Intra-specific pelage color variation in a South American small rodent species (Akodon budini, Rodentia: Sigmodontinae). We studied the variation related to sex and season but not to latitude, because that species of rodent has a latitudinally (and longitudinally and altitudinally) very restricted area of distribution. At that moment, we hypothesized that pelage color would be more homogeneous in males than in females, but the results did not directly confirm our hypothesis, so we showed the complexity of the studied pattern and we speculated about a possible interpretation of the observed data. Regarding season, we hypothesized that pelage color would be darker in winter than in summer, the latter being orange, and the results clearly confirmed our hypothesis. In that study, we concluded that the studied variables should be considered when studying the coloration of specimens for characterization, identification, and discrimination of different taxonomic units based on color.The main goal of the present study was to analyze objectively measured color data from a taxonomically wider sample of mammal species, to identify, if any, common patterns of color changes in the pelage of specimens of small rodents, in relation to a biological (specifically, sex) and some environmental variables (specifically, those related to season and latitude, longitude and altitude).The studied sample includes several rodents species housed in the Mammals Collection of the Field Museum (Chicago, USA) and of the Smithsonian National Museum of Natural History (Washington, DC, USA). We measured the pelage color by taking five measurements on each one of three points over the dorsal and over the ventral surfaces of more than 250 specimens, using two different instruments: an Ocean Optics USB2000+ and an X-Rite eXact spectrophotometer. We used Principal Component Analysis to describe the association between the color variables, sex, season and latitude, and each one of the observations. We then used general linear models of Analysis of Variance to examine relationships between color data, sex, season, and latitude. We analyzed each instrument data set separately.This study shows a number of relationships and associations between individual pelage color variation and a biological (specifically, sex) and some environmental variables (specifically, those related to season and latitude, longitude and altitude) that are common to a number of rodent species specimens. As might be expected, the situation is complex and deserves to be analyzed with care, although some interesting common patterns emerge. We discuss the individual relationship and association of each significant variable on the pelage color and we also discuss the interactions between the variables involved.