SYNONYM: Dunes ashy; ashy.
ALLELES: ahy+ (wild-type), ahy (mutant). Searle (1968) used the symbol da for the mutant.
PHENOTYPE: Ashiness animals appear normal as juveniles. By two months of age, some animals destined to become ashy develop paler than normal ankles above the typical white foot. There may be early depigmentation of the skin at the distal end of the rostrum that leaves a pigmented spot at the tip. Progression of the trait follows a predictable pattern: Between 80 and 120 days the first appearance of gray hairs on the rostrum occurs, and gray begins to extend upward on the limbs, but some animals are still undistinguishable. By 120 - 180 days more than 90% of the homozygotes show some graying on the muzzle and base of the tail. At 6 - 9 months virtually all animals exhibit some manifestation of the trait. Gray on the rump and rostrum becomes more prominent and extensive. The area of graying tends to extend backward from the face, forward from the rump and upward on the legs with each successive molt. The interscapular region of the back is the final area to lighten. By 9 - 12 months most homozygotes show a distinctly "ashy" overall aspect. The face and rump are mostly white, but the dorsum is partially pigmented. Many ashiness animals do not progress beyond this stage, but some continue to lose pigment until the animal is virtually all white. The eyes remain fully pigmented. The trait appears to be due to inactivation of melanocytes. Limited pigmentation can be restored with melanocyte-stimulating hormone (MSH).
INTERACTION: None reported, but high-expression mature ashiness animals likely would exhibit epistasis to yellow, wide-band, dilute and white spotting traits.
SOURCE: About 1960. University of Oregon. Ashiness segregated from a stock of P. m. rubidus taken near Alsea Bay OR.
REFERENCE: Teed et al. (1991). Also see Searle (1968).