Adaptation of Pelage Color and Pigment Variations in Israeli Subterranean Blind Mole Rats, Spalax Ehrenbergi

Abstract

BackgroundConcealing coloration in rodents is well established. However, only a few studies examined how soil color, pelage color, hair-melanin content, and genetics (i.e., the causal chain) synergize to configure it. This study investigates the causal chain of dorsal coloration in Israeli subterranean blind mole rats, Spalax ehrenbergi.MethodsWe examined pelage coloration of 128 adult animals from 11 populations belonging to four species of Spalax ehrenbergi superspecies (Spalax galili, Spalax golani, Spalax carmeli, and Spalax judaei) and the corresponding coloration of soil samples from the collection sites using a digital colorimeter. Additionally, we quantified hair-melanin contents of 67 animals using HPLC and sequenced the MC1R gene in 68 individuals from all four mole rat species.ResultsDue to high variability of soil colors, the correlation between soil and pelage color coordinates was weak and significant only between soil hue and pelage lightness. Multiple stepwise forward regression revealed that soil lightness was significantly associated with all pelage color variables. Pelage color lightness among the four species increased with the higher southward aridity in accordance to Gloger's rule (darker in humid habitats and lighter in arid habitats). Darker and lighter pelage colors are associated with darker basalt and terra rossa, and lighter rendzina soils, respectively. Despite soil lightness varying significantly, pelage lightness and eumelanin converged among populations living in similar soil types. Partial sequencing of the MC1R gene identified three allelic variants, two of which were predominant in northern species (S. galili and S. golani), and the third was exclusive to southern species (S. carmeli and S. judaei), which might have caused the differences found in pheomelanin/eumelanin ratio.Conclusion/SignificanceDarker dorsal pelage in darker basalt and terra rossa soils in the north and lighter pelage in rendzina and loess soils in the south reflect the combined results of crypsis and thermoregulatory function following Gloger's rule.

Sympatric speciation of spiny mice, Acomys , unfolded transcriptomically at Evolution Canyon, Israel

“…The first analysis of incipient SS of spiny mice, A. cahirinus (16), was based on mtDNA and AFLP. Both showed significantly higher genetic diversity on the AS, the more stressful slope, which was also true regionally in Israel both genotypically (20) and phenotypically (21). A. cahirinus in EC I was smaller in size, longer in extremities (20), and lighter in color on the AS than on the ES and in the Israeli Negev desert (21).…”

Reconciling ecogeographical rules: rainfall and temperature predict global colour variation in the largest bird radiation

“…Evidence supporting Gloger's rule has been found in different groups of animals (Miskimen 1972;Zink & Remsen 1986;Lai et al 2008Lai et al , 2016Roulin et al 2009;Pannkuk et al 2010;Friedman & Reme s 2017;Delhey 2018). However, because the tropics are associated with a variety of climatic factors, different patterns of variation have been considered consistent with Gloger's rule, including correlations with rainfall, temperature, UV radiation, latitude, evapotranspiration or combinations thereof (Gipson et al 2002;Caro 2005;Kamilar & Bradley 2011;Singaravelan et al 2013;Bastide et al 2014;Koski & Ashman 2015).…”

Intra-specific pelage color variation in a South American small rodent species

“…CIE Lab color space (Schanda, 2007) is the main reference color space because it is based on the human visual model and therefore includes all of the colors perceived by humans (Ruiz and Pereira, 2014). Besides, this color space was selected because it is more appropriate for the biological aims of this study (Singaravelan et al, 2013).…”