Dandelions, acquired characteristics, and creationism
It is spring and dandelion season. I am performing an interesting experiment in artificial selection. Every day, I go outside and pick dandelion flowers. Dandelion flowers are practically the only vegetable waste that I do not compost.
I usually take a bucket and pop the flowers off, as well as the buds. I am more likely to miss the shorter-stemmed flowers, because they are hidden below the grass, which normally needs mowing. I am therefore selecting for dandelions whose flowers mature and go to seed in less than 1 day or whose flowers grow shorter than the grass. It remains to be seen whether growing too short a stem is adaptive; possibly the grass will then prevent the dispersal of seeds by the wind. If so, we can expect to see a period of stasis.
Even after a few days I find that I am picking shorter-stemmed dandelions. Clearly, the later-maturing dandelions are acquiring the characteristics of those I have just picked -- even though they are not descended from the previous generation. More surprisingly, the previous generation was not short-stemmed but only aspired to shortness before I nipped it in the bud. The effect depends on distance: there appears to be an inverse-square law, with more-distant dandelions less likely to inherit the shortness of their neighbors.
Dandelions undergo spontaneous generation. More surprisingly, they sometimes appear in their fully mature, adult form within less than 30 minutes: I can scour my backyard, find not a single dandelion, and then come back 30 minutes later and easily find more than one.
I have developed a quantitative theory that explains how the dandelions can appear spontaneously and bring with them characteristics that their neighbors only wished they had: Goddidit.
I anticipate green dandelion flowers any day now.
43 Comments
David Stanton · 29 April 2007
I can't argue with that logic. No really, I can't. And you can't make me.
_Arthur · 29 April 2007
According to Wikipedia, dandelions in northern climates like North America are triploid, and practice apomixis, in which seeds don't use the pollen DNA at all, all the genetic material come from the parent plant.
So, dandelion seeds are clonal to the mother plant, except for occasional mutants, which form dandelion microspecies.
It is unclear to me if and when dandelions might revert to good ole sexual reproduction, the article seems to indicate that warmer climates might do the trick, so to speak.
Kevin · 29 April 2007
They are cunning and effective threats to our peace and security.
They are sneaky little tyrants with no morals or decency.
They are:
SADDAMALIONS!
JS · 29 April 2007
wamba · 29 April 2007
I've been undertaking my own multi-year selection program. I use a trowel to dig out the dandelion roots (or most if it). I have seen the same shift to shorter, quicker-blossoming dandelions, and I have also seen a shift to other types of weeds as crabgrass, plantain, etc take advantage of this new selective hurdle the dandelions must face.
It is, of course, hopeless, as some of the neighbors keep dandelions so tall they appear to be cultivated.
khan · 29 April 2007
I like to watch the woodchucks and rabbits eat dandelions.
Jedidiah Palosaari · 29 April 2007
I read through the first half of this post a few times, thinking, "How in the world did they let this guy post on PT, when he obviously has so little knowledge of how evolution works? Am I missing something in his post? Am I not understanding it?"
Then I read the last three paragraphs. Well done.
Aaron · 29 April 2007
_Arthur · 29 April 2007
Here is a paper on the evolutionary implication of apomixis in dandelions and skeleton weed.
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1693208
"It will be argued that the success of apomicts in the long run depends critically on their ability to cross with sexual relatives and that this enables apomixis to survive much longer time periods than generally thought. "
"Most apomictic species are pseudogamous, meaning
that pollen is necessary for fertilization of the central
nucleus in order to develop endosperm. Pollen, however,
has no function for seed production in autonomous apo-
micts like Taraxacum and Chondrilla."
We can count ourselves fortunate that dandelions take revenge for their total absence of a sex life by merely ruining our lawns.
_Arthur · 29 April 2007
By-the-by, I don't think short-stemmed dandelions on a given lawn can be attributed directly to genetic adaptation.
If you mow down a dandelion, or rip off the plant partly, leaving the root, it will regrow shorter leaves and shorter flowers. That has more to do with root resources than with genetics.
When you come up with a dwarf dandelion with discreet, green flowers, be sure to share the seeds with us. Tell us if it makes a better dandelion wine, too.
stevaroni · 29 April 2007
harold · 29 April 2007
Where I come from, dandelion greens were considered a delicacy. The classic presentation was to boil them and serve them with vinegar (the extreme northwestern parts of Europe strongly influenced the cuisine I was raised with, but when the ingredients are fresh, that can be okay). Apparently they're also eaten in parts of Italy, because I've seen dandelion greens on the menu of Italian restaurants.
Although dandelion greens are very, very bitter, they taste pretty good once you get used to that. Italian places sometimes serve them in a salad, in which form the bitterness is quite pronounced. I can only begin to imagine the vast stores of antioxidants, vitamins, etc, that they must contain.
The bottom line is, if you want to get the edge on dandelions, just eat them. Become a dandelion predator. Soon, you'll be wondering why there are so few dandelions left.
David B. Benson · 29 April 2007
The research is far from complete. You need to repeat all experiments while
xeriscaping
and
zeroscaping.
Nic George · 29 April 2007
Well, if they're triploids then the production of hexaploids could lead to sexually fertile individuals. In plants the production of spontaneous ployploids is fairly common.
afarensis · 29 April 2007
I, myself, love dandelions and think you are a cruel, cruel man for performing these acts of scientific terrorism on dandelions. I should mention, I am the chief spokesman and sole member of the Dandelion Liberation Front. Viva La Revolucion!
Frank J · 29 April 2007
Ed Darrell · 29 April 2007
Dandelions are amazing critters.
They are not native to North America. They were brought in after the European discovery of 1492. I know of no place in America that is not within an hour or two of a dandelion, now. I've found them as high as 10,000 feet, and in Death Valley, below sea level. They live in alkaline soils, and in acidic soils. Kids love them, and I get a kick out of them, too.
If you have a field of stout specimens, with flowers rising 12 to 18 inches, you can mow them all off. Flowers will appear next on shorter stems. Mow them again, the stems get shorter. Eventually the flowers will be below the mowing blade. This can be done in as little as two weeks, if the plants are growing rapidly.
How do they do it? Same plant, not successive generations -- "evolution" as Pokeman creatures do it, not as Darwin defined it (that is, it's more metamorphosis than evolution).
It's a great area for research, especially for IDists. But of course, finding the mechanism would most likely be a finding of something other than the hand of God, so IDists won't do the research.
Someone should.
How do the dandelions know?
Sir_Toejam · 29 April 2007
harold · 29 April 2007
My suggestion is to make yourself a dandelion predator.
That's what we used to back when I was a kid. Eat dandelion greens. (True, we didn't eat the flower, but with no leaves, it's in a lot of trouble).
Nowadays, you have to go to fancy Italian restaurant to get dandelion greens. And then you get them in salad, not boiled and served with vinegar, the good old fashioned way.
Sorry Afarensis. I have very little respect for dandelion rights. We have to draw the line somewhere.
I'm not sure we were ever able to eat them fast enough to send them the way of the Passenger Pigeon. But at least we were happy when "dandelion green season" kicked in.
Sir_Toejam · 29 April 2007
oh, and as to why they don't always simply grow short stems to begin with:
well, the reason kids like 'em is cause you can blow the seeds of the head and they float away on the slightest breeze...
so, you have competing selective pressures of grazing and seed dispersal.
how to prove it?
easy:
in the field, you could run exclusion experiments for several generations. It would take quite a while if dispersal is the primary contrary selection pressure, but eventually you should find successive generations producing taller stems and be less reactive to brief episodes of "pruning". easy enough to run a parallel test in a greenhouse as well.
very easy to test if the proximal mechanism is related to hormonal production in the seed-heads. simply remove the seed-heads and substitute an artificially produced (or collected) hormone, and see if the plants still grow tall stemmed flowers.
the latter would be an excellent undergrad project, and the former would be a decent masters thesis.
because it's so simple, it would shock me if it hasn't been done and published already.
afarensis · 29 April 2007
There is also Dandelion wine. Harold will rue the day when the oppressed dandelions rise up and overthrow their oppressors.
The Lizard Queen · 29 April 2007
Might I respectfully request to be the second member of the Dandelion Liberation Front? I'd be very quiet; I could sit in the back and not get in anyone's way.
coachtrenks · 29 April 2007
The flowers are indeed edible as well. When I was a student teacher, my cooperating teacher made his class a nice big bowl of dandelion fritters. They were basically pancake-batter enrobed flowers fried up and coated in powdered sugar. I think anything would taste good prepared thus.
Bob O'H · 29 April 2007
What is this crap? This is nothing to do with evolution! I mean, after all this 'selection' they're still dandelions, aren't they?
Bob
Frank J · 30 April 2007
John Krehbiel · 30 April 2007
Perhaps I'm taking this more seriously than it deserves
:-)
but here http://www.blackwell-synergy.com/links/doi/10.1111/j.1095-8312.2004.00325.x/abs/ is an article about sexual vs. asexual reproduction in dandelions. I believe all of the dandelions in the Western hemisphere are asexual. Just for those who really were curious.
On plucking flowers and the effect on the plant within the same generation; If I stand up and get my head cut off, I think I'd stand a little less tall the next time. I just read a quote (can't remember the ultimate source, but Pinker cited it in How the Mind Works) that rocks are smarter than cats, since rocks at least know enough to get out of the way when they are kicked.
khan · 30 April 2007
Dandelion root tea is an old folk remedy.
_Arthur · 30 April 2007
I believe growing shorter and shorter stems is an commonplace adaptation to grazing.
The first landmowers were cattle.
wamba · 30 April 2007
Tracking Genes For Self-pollination In Plants
David B. Benson · 30 April 2007
Healthy greens:
Raw or steamed, not boiled! Boiling dissolves the vitamin B.
Serve with oil, olive oil is the best.
Without the oil most of the vitamin B is not digested.
Add vinegar to taste. Not required.
And why not eat dandelions? Those is the lettuce liberation league encourage it. :-)
woodsong · 30 April 2007
Alann · 30 April 2007
- Inter-species theism - man vs the dandelion who does God really favor?
- Origin of the dandelion soul - how does divine influence effect the seeding process?
- Do dandelions have a sense of humor - if so do they get the joke?
Hope you enjoy.Scott Simmons · 30 April 2007
Ed Darrell: "I've found them as high as 10,000 feet ..."
Them are some b i i i i i g dandelions!
brightmoon · 1 May 2007
I am the chief spokesman and sole member of the Dandelion Liberation Front. Viva La Revolucion!
2 members now, im joining
y'all can't stand something that looks at all that ugly green monoculture we call a lawn and proundly says, 'hi there, im yellow'
harold · 1 May 2007
David Benson -
I agree with steaming instead of boiling. Boiling results in the loss of some, not all, hydrophilic vitamins, such as the many grouped together under the old term "vitamin B". Also "vitamin C".
However, boiled greens are far better than no greens at all.
Olive oil is also good. It is a common piece of misinformation that hydrophobic nutrients like vitamin A, for example, can't be "absorbed" without the addition of oil or fat to food. This isn't correct, though.
Although there is little or no reason for a healthy person to restrict beneficial oil, the actual human need for essential fatty acids can be met on a very lean diet in reality. A person on a "low fat diet", as long as it is otherwise balanced, can absorb all the vitamins and get all the essential fatty acids.
James McGrath · 1 May 2007
Of course, any true gardening enthusiast would have attributed the creation of dandelions to Satan or an incompetent demiurge, rather than suggest that a benevolent God would torment us with these infernal nuisances! :-)
David B. Benson · 1 May 2007
Harold --- Thanks for the update. :-)
brightmoon · 2 May 2007
how do dandelions know to get shorter stems from being grazed
most plants are very aware of their environments even though we animals dont always realize it .....thinking of plants as merely passive green stuff is for ignorant creationists only, please
plants do everything animals do except walk around and, yes, they do actively respond to being touched especially if that touching is destructive of tissues like grazing
Woodwose · 2 May 2007
This dandelion program is similar to my own program with mosquitos. For the past 60 years I have been eliminating mosquitos that either 1. make enough of a buzz to attract may attention, and/or 2. land and bite with enough vigor to be noticed. The goal is not to eliminate the little pests as they are a component of the bird, spider and frog ecosystems, but to breed for stealth skeeters that don't keep you awake at night or hurt when they take their blood meal.
Leading by example, I note that countless folks have joined my program and are swatting at noisy and painful mosquitos and almost none at quiet unfelt ones.
Ultimately I hope that the mosquitos will breed to inject a small amount of Novocaine equivalent as they probe our skin to deaden the nerves. This has been showing some success as, during long camping weekends in the deep woods, the response to a cheery "How're you doing?" to fellow campers generally generates a response of "I'm feeling no pain."
Keanus · 2 May 2007
I've done no experiments with dandelions in my lawn and fields, but I have made a lot of observations about their adaptability and variation.
Where I mow weekly or more often and for very short grass, dandelion leaves are nearly horizontal the day the flower opens, thet stem seldom holds them any higher than half an inch or so above the grass. But the day the seed head opens up to disperse the seeds, the stem shoots up one to three inches above the grass. And then in a neighboring field where I mow the grass much higher than in the lawn the flower stems consistently grow well above the grass, sometimes as much as 8 or nine inches. And the seedheads come up just as high. In that tall grass the dandelion leaves also grow out at a 45° or greater angle to the ground, the mower being much less of a threat. I've also noticed the there is considerable variation in the serrations along the leaf edges, so much so that I sometimes wonder if I don't have two or more varieties of dandelions. Whatever the explanation, dandelions have evolved a very efficient and effective method for propogating their genome in the fields and lawns of eatern North America, where I live.
David B. Benson · 2 May 2007
Keanus --- Here in the wild west, too...
stevaroni · 2 May 2007
I just want you guys to know that I really appreciate how hard you're working with all these experiments in how dandelions adapt to the pressures of close-crop mowing.
In fact, I'm pitching in to do my part, and hereby offer my yard as an example of an unmowed control sample.
I can now honestly explain to my wife that it's science, not sloth, that motivates me, and I should be commended in my steadfast dedication.
Sniff - with a tear in my eye I thank you all.
Henry J · 10 May 2007
You're welcome.