Albinism, Leucism, Hypo/and Hyperpigmentation, Hypo/and Hyperchromism are all terms that describe genetic mutations of colour pigments.
The incidence of albinism is known in all living species.
In humans the colour pigment is melanin and mutations within these colour genes leads to various conditions such as partial or complete albinism, leucism and vitiligo. Interestingly 'white' humans may be leucistic versions of the original 'black' humans. Full melanin production leads to dark skin,hair and brown eyes-dilution of melanin (leucism) leads to paler skin, hair and blue, hazel or green eyes.
Animals also have melanin but normally have red, yellow, black and brown pigments. Animals with various colour patterns; piebald, tortoiseshell, spotted, striped etc. all have a form of albinism where the normal pigmentation is diluted in certain areas. These patterns may be uniform or random. The black pigments are normal and the lighter markings are the result of incomplete melanin production within that area.
Last year we had some blackbirds hatch out and they had patches of white feathers this is partial albinism called vitiligo where the white patches have no pigment at all.
A leucistic blackbird is grey or brown instead of black. Melanism is a condition that is the opposite of albinism or leucism.
Albinism also occurs in plant foliage when they are deficient in or missing the pigment called chlorophyll. Chlorophyll is the most important photosynthetic pigment in plants and also the one that gives leaves their green colour. Total albinism in plants is lethal-an albino seedling will die within days of sprouting because after it has used the stored energy from the seedcase it can no longer sustain itself. Plants of normal green colour can produce albino shoots and these may survive longer because they receive sustainance from the rest of the plant.
They can not survive sunlight though because they have no protection and will shrivel.
Chimeral variegation:
A white variegation on a green leaf is the result of a plant’s inability to produce any chlorphyll in that area. Coloured variegation in plant foliage is also a type of albinism. Plants bearing such variegation are called chimaeras, more commonly spelled chimeras, because they have more than one type of genetic makeup in their tissues. Variegation can be spots, stripes, leaf margins, leaf spines, regular and irregular patterns within the leaf and any other form. Orange, yellow, and light green leaf colors result from a lesser production of the green pigment chlorophyll, unmasking the orange and yellow carotene pigments and allowing them to appear. Shades of pink, red, and purple in foliage are the result of the anthocyanin pigments being dominant over the chlorophyll in those areas. Autumn foliage of deciduous plants show this range of colours because chlorophyll production ceases as a prelude to winter dormancy.
Cotinus coggygria (smokebush) has totally dark red foliage.
There are also plants like the Lamiums (aluminium plant) that look to have silver areas of foliage.
This is because the unpigmented upper layer of the leaf is lifted from the layer below.
