Transcriptomic analysis of skin pigmentation variation in the Virginia opossum (Didelphis virginiana).

We investigated the gene expression changes associated with skin pigmentation variation between Virginia opossum populations inhabiting tropical and temperate environments. We found that gene expression variation in genes with melanocytic and immune functions is associated with the degree of skin pigmentation variation. Further, we found evidence suggesting that the Wnt/ß-catenin signaling pathway might be regulating the depigmentation observed in temperate populations. We present several alternative hypotheses that may explain Gloger's rule pattern of skin pigmentation variation in the Virginia opossum. Overall design: Skin samples from 13 Virginia opossums we collected, eight from tropical populations and five from temperate populations. The mRNA was extracted, sequenced (RNA-Seq) and analyzed.