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Dryad

Evolution of Pelage Luminance in squirrels (Sciuridae)

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Feb 17, 2020 version files 43.30 KB

Abstract

Sciurids have one of the greatest diversities of color patterns and hues among mammalian families, but whether these color patterns conform to Gloger’s Rule has not been investigated. Gloger’s rule is the ecogeographic trend that describes the tendency of animals’ pelage to be darker in warmer and wetter environments. Several mechanisms have been proposed explain this trend that relate to various environmental variables. However, these variables frequently correlate with each other which can cause increased Type I error rates in conventional analyses with a single dependent variable. Here we use a new phylogenetic comparative method that implements path analysis to produce a hypothesized series of cause and effect relationships between predictor variables to form a path model. This multi-regression approach allows for the simultaneous exploration of the effects of numerous predictor variables. Our path analysis results using 137 Sciurid species show that squirrel pelage luminance conforms to Gloger’s rule and that there is a significant evolutionary relationship between precipitation and pelage luminance. Also significant were that other commonly found variables (humidity, temperature, and vegetation cover) did not have strong relationships with pelage luminance. Our findings demonstrate that utility of path analysis in phylogenetic comparative studies in studying a trait influenced by several covarying variables.