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What are these conditions?
Albinism is characterized by the absence or significant reduction of melanin, the pigment responsible for the coloration of skin, hair, and eyes. Individuals with albinism typically have pale or white skin, hair, and sometimes feathers or scales. Their eyes may appear pink or light-colored due to the lack of melanin in the irises.
Melanism, on the other hand, is characterized by an excess of melanin, leading to dark or black coloration of skin, fur, feathers, or scales. Melanistic individuals, like black panthers or black squirrels, exhibit a surplus of melanin
Both albinism and melanism in animals are subject to the same genetic and environmental factors as in humans.
Causes of albinism and melanism:
Albinism is primarily caused by genetic mutations that affect the production of melanin. Melanin is synthesized in specialized cells called melanocytes, and any genetic alteration that impairs the functioning of these cells or the melanin synthesis can result in albinism. There are several genes associated with different types of albinism, with each gene playing a specific role in melanin production.
Due to this, Albinism is usually inherited in an autosomal recessive manner, meaning that an individual must inherit two copies of the mutated gene (one from each parent) to manifest the condition.
Like albinism, melanism is primarily driven by genetic mutations, but in this case, the mutations result in an overproduction or hyperactivity of melanocytes, leading to an abundance of melanin. These mutations can affect various genes involved in melanin synthesis.
While genetic factors are the primary drivers of melanism, environmental conditions can also play a role. For instance, increased exposure to certain environmental toxins or pollutants can lead to melanin overproduction in some organisms (often seen in industrial areas).
Problems associated with these conditions:
Albinism:
Sun Sensitivity: Albino animals have a lack of melanin, which provides protection against harmful UV radiation. As a result, they are highly susceptible to sunburn and skin damage, making them vulnerable to skin cancer.
Visual Impairments: Albinism often affects the eyes, leading to problems like nystagmus (involuntary eye movement), strabismus (crossed eyes), and photophobia (light sensitivity). These visual impairments can hinder an animal's ability to hunt, forage, and navigate.
Predation Risk: Albino animals are more visible to predators due to their light-colored fur or feathers, making them easier targets. They may have reduced chances of survival in the wild.
Social Challenges: In some animal species, individuals with albinism may face social challenges, such as exclusion or aggression from others in their group due to their different appearance.
Melanism:
Thermoregulation: While melanism can provide advantages in cooler environments by aiding in thermoregulation through increased heat absorption, it can be a disadvantage in hot climates. Melanistic animals may struggle with excessive heat retention in warmer conditions.
Predation Risk: In certain environments, melanistic animals might stand out against their surroundings, making them more visible to predators. This can increase their risk of predation.
Genetic Health: In some cases, the genetic mutations leading to melanism can have negative side effects on an animal's overall health or fitness, such as reduced reproductive success.
Ecological Impact: Changes in the frequency of melanistic individuals within a population can influence predator-prey dynamics and other ecological relationships, potentially disrupting the balance of ecosystems.
Albinism and melanism are often seen in nature!
Albinism in Animals:
Mammals: Albino mammals, such as albino squirrels, deer, and rabbits, have pale fur, pink or light-colored eyes, and skin that is highly sensitive to sunlight.
Birds: Albino birds can have white feathers, pink eyes, and pale-colored beaks and legs. Albino birds may also exhibit reduced vision.
Reptiles and Amphibians: Albino reptiles and amphibians, like albino snakes and frogs, often have white or pale-colored skin and eyes.
Fish: Albino fish can have pale scales, fins, and eyes. In the case of aquarium fish, albino varieties are sometimes bred for their unique appearance.
Melanism in Animals:
Mammals: Melanism in mammals can result in animals like black panthers (melanistic leopards or jaguars) and black squirrels. These individuals have dark fur or skin coloration.
Birds: Some bird species, such as melanistic pheasants and crows, can exhibit dark plumage due to melanism.
Reptiles: Melanism can occur in reptiles like melanistic snakes and turtles, leading to dark skin or scales.
Insects: In the insect world, melanism can result in darkened coloration in species like moths, butterflies, and certain beetles. This adaptation can aid in camouflage.
Enjoy some beautiful examples of these conditions in the animal kingdom:
Team Let's Biologue
References:
Albinism - NHS. (n.d.). Retrieved September 6, 2023, from https://www.nhs.uk/conditions/albinism/
Albinism: Causes, Types, Pictures, Symptoms, and More. (n.d.). Retrieved September 6, 2023, from https://www.healthline.com/health/albinism
Bellani, G. G. (2020). Genetics. Felines of the World, 375–392. https://doi.org/10.1016/B978-0-12-816503-4.00008-8
Clusella Trullas, S., van Wyk, J. H., & Spotila, J. R. (2007). Thermal melanism in ectotherms. Journal of Thermal Biology, 32(5), 235–245. https://doi.org/10.1016/j.jtherbio.2007.01.013
Melanism - an overview | ScienceDirect Topics. (n.d.). Retrieved September 6, 2023, from https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/melanism
Nature’s colors – Albinism, melanism, and other genetic variations - ACMCR. (n.d.). Retrieved September 6, 2023, from https://acmcr.org/content/natures-colors-albinism-melanism-and-more/
What makes an animal albino? - DNR News Releases. (n.d.). Retrieved September 6, 2023, from https://www.iowadnr.gov/About-DNR/DNR-News-Releases/ArticleID/2711/What-makes-an-animal-albino
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