Obviously, variation in traits is present in all populations and all species, but its quite easy to forget that - a mallard looks like a mallard, right? Evolution acts upon this variation, be it timing of flowering, anti-predator behavior or body size, constantly. I find variation in "characteristic" traits very interesting (and by "characteristic", I mean how a naturalist would recognize a species, for instance in plants this might be color, growth form, leaf shape, etc.). I've been noting these for quite awhile and keeping a photo log - mostly of flower color, which is especially interesting to me - here's a selection.
This isn't meant as a real ecology post, just an appreciation for the natural world, but do bear in mind the little tidbits of science thrown in - they'll only make it more interesting. As Huxley famously said, "To the person uninstructed in natural history, his country or sea-side stroll is a walk through a gallery filled with wonderful works of art, nine-tenths of which have their faces turned to the wall."
I'll mostly put a "normal" picture first and then the mutant. Here's a normal
Mimulus guttatus, the common yellow monkeyflower - a widespread, common and lovely species.
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| McLaughlin Reserve, Lake County, CA. |
And a weird red mutant:
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McLaughlin Reserve, Lake County, CA
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A normal
Tritelia laxa.
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| Berryessa-Knoxville Rd., Napa County, CA |
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And a white one:
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| Berryessa-Knoxville Rd., Napa County, CA |
A normal blue-eyed "grass" (really an iris),
Sisyrinchium bellum:
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| McLaughlin Reserve, Lake County, CA |
and a white one:
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| McLaughlin Reserve, Lake County, CA |
Normal
Mimulus nudatus, a cool serpentine endemic in the northern coast range.
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| McLaughlin Reserve, Lake County, CA |
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And a weird beige morph:
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| McLaughlin Reserve, Lake County, CA |
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And both normal and white morphs of
Collinsia sparsiflora:
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| McLaughlin Reserve, Napa County, CA |
Normal and white morphs of
Mimulus layneae. Interestingly, the two white individuals in this population had flatter flowers as well.
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| McLaughlin Reserve, Lake County, CA |
Why are white flowers so common in plants? Purple or reddish colors are caused by a group of chemicals called anthocyanins. These are synthesized in a pretty complex pathway that involves a bunch of steps, all mediated by proteins. If a mutation (or developmental issue), interrupts the function of any of these steps, you get a loss of function, which in this case becomes a white flower.
In some species, there is simply a polymorphism - its not rare to have differently-colored flowers (or -colored seed, or -shaped fruit, etc.). This
Leptosiphon sp. has both pink and white flowers in roughly equal proportions in a population I looked at.
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| McLaughlin Reserve, Lake County, CA |
Like Leptosiphon, many other members of the Polemoniaceae have white/colored polymorphisms within populations. Navarretia mellita (often a sandy plant!), is one:
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| McLaughlin Reserve, Lake County, CA |
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| McLaughlin Reserve, Lake County, CA |
Of course, color polymorphisms aren't restricted to flowers, or even plants. A cool hypothesis to explain the existance of color polymorphisms in many species of raptors is that it is harder for prey to figure out what is a predator if they all look different. To the best of my knowledge, that hypothesis is still up for debate, but its clever and seems logical. Here is a pair of Variable Hawks,
Buteo polyosoma:
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| Bosque del Pomac, Lambayeque, Peru |
And another morph, of the same species!
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| A juvenile, I think. Bosque del Pomac, Lambayeque, Peru |
I don't know any hypotheses for the maintenance of color polymorphisms in caterpillars, but some have them. Hyles lineata feeding on Abronia villosa:
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| San Diego Co., CA |
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| San Diego Co., CA |
