Why is it present?
OK; some fungi rely on insects to carry the spores away, but the majority don’t and yet there’s an incredible range of colours.
The pigmentation is also called melanin and, just like in people, is there for UV protection.
well sure, but why the diversity in colour (melanin in humans doesn’t cause us to be bright yellow/red/green/purple/blue), or is that just because there’s no reason not to have those colours?
Your guess is probably as good an explanation as any. Once the basic pigment has been taken care of, the genes controlling pigment biosynthesis may be free to mutate without much detriment to the fungus. In pathogenic fungi, albinism (complete lack of pigment) is strongly correlated with reduced pathogenicity. I haven’t seen a study that addresses the variation in pigment color, though.
In addition to UV protection quite a few of those pigments are antimicrobial agents, melanin included. Remember these spores are expected to lie in microbe rich environments, often for considerable lengths of time. They have to be resistant to the enzymes of any microbe that gets the jump on them in germination. Basically each species tends to have some compounds that are hhighly resistant to enzymes produced by every other bacterial and fungal species. Just so happens these compounds also tend to be coloured.
It’s also worth remmebering that colour tends to be fairly plastic. Grow those suckers on different media and often the colour will be completely different, which suggests that it may be simply a case of waste material being bound to the spores to make them more toxic.
also…
I believe I read once that Amanitas (sp?), like the toadstools in Mario, have the distinctive red cap as warning coloration.
There are a bunch of species of genus Amanita, and the caps range in color from white to tan to pale orange to bright freakin’ red. Some of the alkaloids, most notably ibotenic acid and muscimol, but I’m sure a ton of others, are powerful liver toxins. If you eat enough of the wrong species of Amanitas (it’s pretty tricky to tell them apart) you can die a slow, painful death. I’m sure nuking your liver isn’t fun, so you could see how evolution would favor the bright red and yellow to warn animals away.
Don’t know about the warts though… cheers
Adam420: Unfortunately that really doesn’t hold true. One of the worst Amanitas, The Destroying Angel ( Amanita ocreata ) is a pallid white ( though it may fade a bit with age ).
The most common cause of mushroom fatality in the U.S. in probably The Deathcap ( Amanita phalloides ) and it has an often subdued, rather dingy at times, olive-yellow cap. The problem with that one is it is nearly identical to the highly desired and sought-after edible, the Coccoli( Amanita calyptrata ). It also closely resembles some edible East Asian mushrooms, but the folk ID methods imported by some immigrants to CA don’t work well with the CA mycota ( fungal flora ). Hence we’ve had several fatalities among immigrant communities from Vietnam, Laos, and the like over the last several years.
So bright coloration in fungi isn’t necessarily a good diagnostic tool for determing toxicity. In fact, some bright-clored fungi are good edibles - Chantarelles, for example.
- Tamerlane
You are correct Tamerlane…
I didn’t mean to imply that red=poisonous white=ok, but I think that red pigments in some toxic or semi-toxic species may be related to warning coloration. Maybe not.
Peace