ciało-człowieka: Albinism

Evidence: 100 • authority: 72

Albinism is the congenital absence of pigmentation (in mammals, melanin) in an animal or plant resulting in "hair being white, red, or yellow", "feathers, scales, and skin being yellow", "eyes being red, pink, purple, violet, or blue", and "leaves or stems being white or yellow", if applicable. Individuals with the condition are referred to as albinos. Varied use and interpretation of the terms mean that written reports of albinistic animals can be difficult to verify. Albinism can reduce the survivability of an animal; for example, it has been suggested that albino alligators have an average survival span of only 24 years due to the lack of protection from UV radiation and their lack of ca…

Evidence: 32 • authority: 72

Animal coloration is the general appearance of an animal resulting from the reflection or emission of light from its surfaces. Some animals are brightly coloured, while others are hard to see. In some species, such as the peafowl, the male has strong patterns, conspicuous colours and is iridescent, while the female is far less visible. There are several separate reasons why animals have evolved colours. Camouflage enables an animal to remain hidden from view. Animals use colour to advertise services such as cleaning to animals of other species; to signal their sexual status to other members of the same species; and in mimicry, taking advantage of the warning coloration of another species. S…

Evidence: 32 • authority: 88

Human Albinism and Animal Models of Albinism. Ten phenotypic forms of oculocutaneous albinism (OCA) and four forms of ocular albinism (OA) have been identified in man. All have optic neuronal decussation defects at the optic chiasm. Thus any proposed animal model for these disorders must share optic neuronal decussation defects in addition to hypopigmentation. Three, tyrosinase‐negative (ty‐neg), yellow mutant (ym), and platinum (pt), OCA appear to be allelic in humans. Two, ty‐neg and pt, OCA appear to be analogous to c‐locus mutants c/c and c p /c p in mice, but no homologue is known in mice for ym OCA. Tyrosinase‐positive (ty‐pos) OCA, which is nonallelic with ty‐neg OCA, shares many mor…

Evidence: 20 • authority: 92

Sex Determination in Reptiles: A Review.. Reptile biodiversity is rapidly declining, with over 11,733 recognized species across 1226 genera being documented, many of which are endangered. Captive breeding programs play a crucial role in conservation; however, effective management requires accurate sex determination, especially due to the fact that many reptile species exhibit minimal or no sexual dimorphism. When present, sexual dimorphism manifests as differences such as size, coloration, and morphological features influenced by evolutionary pressures and hormones. Various sex determination techniques are employed due to the lack of external sexual characteristics in many species. These me…

Evidence: 20 • authority: 72

The American alligator (Alligator mississippiensis), sometimes referred to as a common alligator or just gator, is a large crocodilian reptile native to the Southeastern United States. It is one of the two extant species in the genus Alligator, and is larger than the only other living alligator species, the Chinese alligator. Adult male American alligators measure 3.4 to 4.8 m (11.2 to 15.7 ft) in length, and can weigh up to 450 kg (1,000 lb), with unverified sizes of up to 5.84 m (19.2 ft) and weights of 1,000 kg (2,200 lb) making it the heaviest member of the family Alligatoridae, and the second longest one, after the black caiman. Females are smaller, measuring 2.6 to 3.35 m (8.5 to 11.0…