Abstract
The possession of fur or hair is a defining characteristic of mammals and
can occur in a variety of colours and patterns. While genetic determinants
of coat colour are well described in eutherian ‘placental’ mammals, the
other major mammalian infraclass, marsupials, is grossly understudied. The
fur of the common brushtail possum (Trichosurus vulpecula), an iconic
native mammal found throughout Australia and introduced into Aotearoa New
Zealand, possesses two main colour morphs: grey and black. To identify
genetic variants associated with coat colour, we performed a genome wide
association study (GWAS) with genotype by sequencing (GBS) data. Single
nucleotide polymorphisms (SNPs) on chromosome 3, close to the agouti
signalling protein (ASIP) gene that controls the temporal and spatial
distribution of pigments in eutherian mammals, were identified.
Fine-mapping identified a C>T variant at chr3:100,483,705 that
results in a p.Arg115Cys substitution of the ASIP protein, and animals
homozygous for this variant have black fur. In addition to uncovering the
first genetic determinant of coat colour in a natural marsupial
population, comparative analysis of ASIP in divergent marsupial species
identified the Dasyurids as having accelerated evolution, reflecting their
well described diversity of coat colour and pattern.