Has anyone ever studied how a leaf flutters in the wind? An aspen leaf flutters differently from an oak leaf-and the frequency of flutter might be of benfit to the leaf (cooling , oxygen exchange, etc.0. I’ve noticed that palm leaves don’t flutter-is this good or bad for the plant? anyway, when trees evolved, was the wind more gentle? just wondering if the different leaf shapes confer an advantage. I’m looking at ginko leaves now-they flutter a lot.
I can only offer an uneducated guess, and stand open to correction.
Leaves evolved not because of flutterability, but to catch the maximum amount of sunlight and rainfall. Flutterability is just an unfortunate byproduct of this, much like male pattern baldness.
From what little I know about evolution:
The evolutionary process does not select for, but rahter against. That is, leaf “flutterability” does not have to add anything, it simply needs to not subtract. So, how the leaf falls away from the tree was probably not something that really matters.
Rereading the OP, I think you are talking about while the leaf is still attached to the tree, yes? In that case, yes, the shape of the leaf may very well have been selected for, out of a miriad of different leaf shapes that did not work as well. E.g. big heavy palm leaves that can withstand hurricane force winds (as the tropics are prone to) vs little aspen leaves that don’t get as much wind, so therefore can be more fragile but better able to absorb the lower intensity light energy.
Like, tdn, tho, I await someone with a more proven theory.
But male pattern baldness increases the ability to catch the maximum amount of sunlight and rainfall. You can’t call it an unfortunate byproduct!
I’d find that funny if it weren’t for the damn sunburn on the top of my head.
My face -> :mad:
Well, I guess i’m asking; is photosynthesis improved by leaf flutter? Suppose you have a tree with large area, heavy leaves- would smaller leaves which flutter be more efficient?.Or take species whose leaves are rigidyly attached-like cycads and palms-are these species less efficient because their leaf surfaces are stationary?
Pines are interesting-their needles are low area/low effciency. by they are hatd to blow off. is that why conifers survive at higher altitudes?
More surface area = more photosynthesis.
More surface area = more vulnerability to leaf loss by wind, or heavy accumluation of ice / snow.
Thoughts on the subject:
Evergreen-broadleaf (palm-types) have heavy leaves that can withstand high winds (but would damage the tree in an ice- or heavy snow- storm)
Deciduous (aspen-types) have a lot of light leaves that fall off in autumn to make use of a shorter growing season. Said leaves can blow clean off in high winds.
Coniferous (pine-types) have needle shaped leaves that can stay on the tree year round (to make use of whatever sunlight they can) and are solid enough to withstand accumulation and windstorms.
I would suspect that conifers are more favored in higher latitudes tahn deciduous when the variability of the season comes more into play (or the season of no snow is simply too short).
Again with the disclaimer: I’m a physics-type. I look forward to input from a biology / botony type.
Hmm. So they all accomplish the same thing, but take advantage of (or protect from) the climate in which they grow. Makes sense to me.
This doesn’t explain the question in the OP, though, where different deciduous trees in the same area have different flutters. One has to wonder, though, how indigenous those trees are. Perhaps not all are perfectly well-adapted to their current environment, but still thrive.
Until a botonist comes along, I’m saying random genetic drift. That’s my story and I’m sticking to it.
Oh, yeah. Aspen vs. oak? I wouldn’t have the foggiest idea.
Yells: Is there an arborist in the house?
Oh, one last thought, this is actually good fodder for GQ. I’ll flag down a passing mod and see what they think.
Are you suggesting that men’s hair is deciduous?
It’s Magically Deciduous!
Off to GQ.
I’m beginning to believe Quakeys down here in the valley suffer because of inconsistent windy/breezy intervals, while up on the Grand Mesa they do just fine. Our Extension Office has conducted a study of wind velocity and frequency vs life span of Quaking Aspens in the Grand Valley and has begun to correlate the importance of air movement to overall health and vigor of the species.
Every Spring we have a massive invasion of tent caterpillars, that while not deadly can defoliate and stress a tree substantially; a regular, stiff and shuddering wind will prevent a widespread invasion of trees that flutter, specifically our poplars.
That being said, if there is any evolutionary advantage to be had it’s probably due to the increased rate at which a fluttering leaf dries. You have guttation and you have precipitation; a faster drying time reduces the moist-beyond-guttation period, thereby reducing the plant’s susceptibility to stresses and pathogens.
This is incorrect. Natural selection has not been termed the “creative force of evolution” for naught. Indeed, the whole point of natural selection is that those traits that yield an advantage to the individual bearing them, no matter how minute, will tend to be selected for. Adaptation is not the product of simply culling the weak, but favoring the strong, as well.
Diversity might be a benefit in itself. See many elm lately? Chestnuts? Both were major constituents of the American tree population when I was born.
Climate varies not just geographically, but over periods of decades to centuries (the lifespan of many tree) and certainly millenia (the possible lifespan of a successive growth forest). Maybe this year or decade will be better for oaks, but passable for aspen (I’m told the late 70s/80s were a real boom time for Aspen). It probably doesn’t matter if a leaf shape, root system, etc. is optimal for a given set of conditions, so long as it is good enough to hold its own against the competition, and it may even turn out to have unforeseen advantages someday.
Even when thre is a demonstrable selective advantage for one over another, the overall selective pressure may not be strong. Other factors like speed of growth, tolerance of soil, etc. may further obscure the effect. Trees are like romantic partners, a mixed bag: you take them as a package, and while they may adapt or change, none is perfect in every regard. Despite popular onceptions and media images, no one type seems to have a lock on reproductive fitness. Types at a real disadvantage are rare/extinct or arise as nature’s experiments.
Disregarding the selective effects, we should keep in mind that plants don’t choose shapes the way we choose a business suit. Morphology is just an interplay of very fuundamental physical processes interacting with each other. In molecular embryology (or any diverse garden), you’ll see many extremely simple mechanisms – often as simple as changing chemical gradients from a point (or other shape) source-- interacting over time to develop structures, and also cause them to later selectively involute – your fingers didn’t just grow out of your palm, but start as more of a pad, until the spaces (webbing) between them involuted
In othr words, given a genetic blueprint that encodes basic mechanisms and crude ratios, it may not be practical for an oak to evolve pine needles. Both may have evolved from a common ancestor, but ther may be no practical path (with good sustainable intermediates) of evolution leading from one to the other. Evolution usually “evolve” dinosaurs into, say, mammals. A lot of species just end up as dead ends, leaving others to adapt and change as best they can.
For current conditions, the basic concept of a leaf seems to be such good idea that the tiny details don’t matter much. The flora of “the dinosaur era” were mostly as different from today’s plants as the dinosaurs are from mammals – and that was really remarkably recent on a geological scale.
If the Earth were a a one-year old --call it a New Year’s Baby- then the oldest known (micro)fossils would have showed up in late March (life may be older than that, but our oldest know rock samples only date to mid-March, a week or two earlier). Elements of our environment as basic as our oxygen atmosphere didn’t arrived until mid to late August, when the kids are getting ready fo school, and the first cells with nuclei (like paramecium, yeasts, and us) would have shown up around Labor Day. As we geared up for Thanksgiving (USA) life on Earth was experimenting with with all sorts of bizarre shapes and body types (the Cambrian explosion) It is generally believed that life became common on land around Thanksgiving (but there’s some evidence that it may have been a bit earlier). It really wasn’t until December that we settled into the basic familiar land fauna shapes, like quadrupeds.
The Age of the Dinosaurs was from about Dec.15 to Christmas – and the plants they knew weren’t much like our modern woody flowering plants. The world hadn’t even evolved “trees”, as we know them, yet. It’s really hard to imagine, say, thousands of miles of towereing ferns blowing gently in the breeze. That’s more alien than anything on the Sci-Fi Channel. In fact, one species of early proto-pines has survived to this day – about 100 Wollemi pines were found about 10 years ago in an exceptionally rugged patch of Australia (so rugged that it was almost never visited by Western man, even after this much-publicized discovery, despite being just ~125 miles from Sydney) The more photos you see of them, the less pine-like they seem, but the overall family resembance is unmistakable.
On this scale, our familiar trees today are New Years Eve decorations – hardly as fundamental and enduring as we imagine.
Just a couple more elements to toss into the mix:
Greater leaf surface increases transpiration/water loss. I believe the spines on cacti are actually modified leaves. In order to reduce water loss, they have evolved such they have minimal flutterability.
The cumulative wind force against a leafed deciduous tree is tremendous. As I recall, leaves vary considerably in their aerodynamics. On a related factor, trees also vary greatly in the depth and spread of their roots.
It is my understanding that the view that advantages are selected for is less correct than the view that disadvantages are selected against. Advantages are selected for in that the species (or sub-species or gene-group) that don’t have the advantage are not selected. (hmmm… maybe my use of “selected against” was unclear. Is that phrase used much or at all?) The point of my (perhaps poorly chosen) phrasing was that malignant gene combinations get culled from the population while benevolent and benign ones remain. The difference being in simply how one explains the existance of useless genes. One can’t argue that they have been selected for.
It’s all relative though, isn’t it? In a system of finite resources, one genotype’s disadvantage is everybody else’s advantage, and vice versa.
First, at least some researchers have studied how tree leaves perform in the wind, and found many of them well-adapted to minimizing wind forces (for instance some will naturally curl up when the wind blows, thereby presenting less area for the wind to push on). Sorry, don’t have a cite right now for the research. It does seem quite likely that this is a selected advantage. Of course, there are other selective factors: maximizing light capture, efficiency in growth, etc. going on, as well as some chance and the difficulty of evolving major changes in leaf shape. But wind resistance does seem to be a reasonably important factor for some trees.
Second, JustAnotherGeek, I’m afraid that you seem to be making an incorrect distinction in the way natural selection works. For both favorable and unfavorable genes, natural selection changes their frequency in the gene pool, just in opposite directions. Say, half the population has gene A, which doubles the number of viable offspring, and half have gene B, which gives a fifty percent chance of immediate death (these are of course ridiculously exaggerated effects for any one gene). Next generation, 80% have gene A, and only 20% gene B. Rinse and repeat, and gene A will be close to 100%, gene B is gone.
No need to look at populations going extinct or anything like that.
When the subject is evolution, you should probably listen to Darwin’s Finch