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how do albinos happen in the wild, is it just a freak accident?

>>how do albinos happen in the wild, is it just a freak accident?

Sort of. Albinism (amelanism) occurs when there is a mutation (an error) in one of the genes that is responsible for the production of the pigment melanin. These faulty genes don't work properly and so they don't produce pigment.

Snakes, like most other vertebrates, have two copies of every chromosome, therefore two copies of every gene. If a snake gets two working copies of the melanin genes (one copy from each parent), the snake produces melanin and is normally pigmented.

If a snake gets one good and one bad copy, it produces enough melanin with the good copy and so is normally pigmented.

If a snake ends up with two copies of the faulty gene, it cannot produce melanin and ends up being albino.

It is rare in the wild because two events have to occur -

1. the albino allele has to be formed by a mutation in the population. This event is going to be extremely rare. There are probably 10s of thousands of genes in a species of snake. The odds that the mutation will occur in the right place in the right gene are very, very low (although not all genes have an equal probability of mutation). Furthermore, that mutation has to occur in a cell that is capable of passing it on to the next generation, such as an egg or sperm cell or an early embryo.

2. Then, if the first improbable event occurs, two animals that carry that faulty gene have to mate and produce an offspring with two copies of the faulty gene.

Again, the probability that two animals that carry the same mutation will run across each other is rare and so the combination of both 1 and 2 is rare. Once the faulty version of the gene exists, population genetics comes into play, so if an albino is found in an area, it makes it more likely that other albinos could be found there.

When you add to that the chances that an albino snake will survive in the wild, it becomes even rarer. Albino snakes are more conspicuous to predators and are more likely to be eaten. And even if the predators don't get them, they don't have melanin to protect them from the sun and less likely to live a long time if exposed to the sun's radiation. Consider that fewer albino lizards have been found than snakes. Albino lizards basking in the sun would be exposed to harmful radiation even faster than snakes which generally don't bask in direct sunlight as often or as long.

This is why most of the albinos that have been found have been babies. They don't live very long in the wild.
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Chris Harrison