What is the term for black coloration in rats? - briefly
The black coat in rats is termed melanism. It arises from a genetic mutation that elevates melanin production, resulting in a uniformly dark phenotype.
What is the term for black coloration in rats? - in detail
The black coat phenotype in laboratory and pet rats is referred to as «melanism». This condition results from an increased production of eumelanin, the dark pigment synthesized by melanocytes. The genetic basis typically involves mutations in the c locus, which controls the type and amount of melanin deposited in the hair shaft. When the c allele is functional, the default coloration is agouti; loss‑of‑function mutations produce a uniform black coat.
Key characteristics of melanistic rats include:
- Uniformly dark fur without the typical banded hairs of the agouti pattern.
- Darker eye pigmentation, often appearing red or ruby due to the lack of protective pigment.
- Increased resistance to ultraviolet radiation, owing to higher melanin levels.
Breeding considerations:
- The melanistic trait follows an autosomal recessive inheritance pattern; both parents must carry at least one copy of the mutant allele for offspring to display the black coat.
- Heterozygous carriers appear phenotypically normal but can be identified through genetic testing.
- Crosses between melanistic and agouti individuals yield a 25 % probability of producing black offspring in the F2 generation.
Health implications are generally minimal, though some studies suggest a correlation between high melanin concentrations and reduced susceptibility to certain skin conditions. However, excessive melanin may mask early signs of dermal lesions, necessitating regular veterinary examinations.
In summary, the term «melanism» encompasses the genetic, phenotypic, and breeding aspects of black coloration in rats, providing a concise designation for this distinct coat color.