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Butterfly Unlocks Evolution Secret
Anonymous Coward writes "The BBC has an article about a dramatic discovery in the quest for understanding evolution. From the article: 'Why one species branches into two is a question that has haunted evolutionary biologists since Darwin. Given our planet's rich biodiversity, "speciation" clearly happens regularly, but scientists cannot quite pinpoint the driving forces behind it. Now, researchers studying a family of butterflies think they have witnessed a subtle process, which could be forcing a wedge between newly formed species.'"
The article says that the mutations have different wing-markings, and descendents prefer mating with those of the same wing-markings, keeping the two paths separate.
IANAEB (Evolutionary Biologist), so I'm just going by the article here, but it seems like the process itself was obvious (or at least pre-supposed) as you suggest, it's the chance to witness it in nature that's exciting here.
... that's all i got. IANAEntomologyst either.
I can't really answer your butterfly question, but I can point out that every insect has multiple stages of life. Flies start out as maggots,
While we're asking the tough questions, it seems like the one big gun the Divine Design people have left is in the differing number of genes between species. If all offspring have the same number of genes as their parents, and all species on earth are evolved from one original life form, shouldn't all creatures have the same number of genes? Are there any theories out there regarding how genes are added or subtracted over time?
While we're on the subject, I might as well reply to myself and point out a selective advantage to multi-stage lifecycles, namely that the different stages do not compete with each other: they eat different food, and fill different evolutionary niches. This means that in times of scarcity there is little advantage in adults behaving like those of some non-metamorphising species, who will kill youngsters, as they are in direct competition with them for resources.
It is also very unlikely that full-blown metamorphosis arrived on the scene ex nilho. There is apparently ample evidence in the historical record for incomplete metamorphosis, via a 'nymph' stage.
You may find the following page interesting: "How did the process of metamorphosis evolve?".
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"Why don't the butterflies want to breed with butterflies that look slightly different?"
Quoted from TFA:
"The reason evolution favours the emergence of a "team strip" in related species, or sub species, living side-by-side is that hybridisation is not usually a desirable thing.
Although many of the Agrodiaetus species are close enough genetically to breed, their hybrid offspring tend to be rather weedy and less likely to thrive. "
I agree. The BBC report seems confusing and explains the after effect of speciation (distinct wing markings) as the cause of speciation and as being useful because it prevents hybridisation.
But prior to divergence it wouldn't be hybridisation.
I suspect it's just poor wording on the reporter's part and the full story is something like:
There are butterflies of different species present in the same area. In order to prevent hybridisation they select mates on the basis of wing pattern. Some members of a species develop an abnormal wing-pattern. Although they _could_ breed with other members of the species, the inbuilt preference for mating with similarly-striped partners means they only mate with each other. This isolation of their genetic pool leads to an accumulation of mutations which make it impossible to breed with their ex-species. Now they are a new species.
(Also, I though hybridisation could be useful when there wasn't enough genetic variability in the parent populations.)
This article from the BBC is misleading. I tracked down the original article in Nature.
The researchers didn't actually unlock any major secrets. It is no secret that two species who would not produce viable offspring together will try to avoid mating with each other. There are various mechanisms for doing that - having different wing colors so that species can distinguish their optimal mating partners is one method. If the two species are geographically separated, there is no need to develop other methods of separation, and thus their wing colors can look similar. There is nothing new about this.
Also, the BBC article never explains that the speciation of these butterflies occurred while they were geographically separated (this is called allopatric speciation, and the Nature article specifically states that the butterflies evolved this way). The species only developed different wing markings when they came back into contact with each other. This makes a lot of sense - they were now genetically very different, and offspring between members of different species would not be successful, so they needed ways of telling each other apart.
It's a nice finding, but certainly not the unlocking of a major secret.
Here is what I think about butterfly (and any creature that goes through a laval/pupation stage)
By being born with little more than the ability to eat and move to the next meal they save the parent a huge amount of energy. Usually a parent creature has to drop a lot of their energy and food into incubating or laying an egg that will feed the young until they reach a fully matured stage.
With butterflies, flies and most other insects it becomes more efficient to lay an egg with only enough energy to create a rudimentary creature that does little more than eat and move to its next meal. This allows the parent to lay many many more eggs that have a chance of survival than if their eggs hatched directly into adult forms.
Now comes the fun part. The insect larva can slowly continue to develop into its adult form. It can develop wings, shed the extra legs change form as it matures. This is very bad for the species as it will eventually reacha point where it is niether lavae nor adult. It will go through some rather awkward stages where it becomes quite vulnerable. The earliest insects would likely have gone through this transformation as a gradual process while they ate, and probably wouldn't have a cocoon stage at all.
The species that will survive the best are going to be the ones that can hold off this transformation until they have enough food stored in their bodies to go hide somewhere. By hiding and going through the transformation in one go they avoid any awkward vulnerable stages (like developing large wings but having a body too big to fly). The ones that have the ability to create some form of protective shell (silk, folded leaves, or burrowing into the earth or into wood) have an even better chance of survival.
Basically the whole larva>cocoon>adult thing is to minimise the amount of energy the parent needs to spend on each egg, allowing more eggs and thus a greater survivability of the species.
Just an idea.
Even though this may be a troll, I want to respond anyway.
I cringe every time I hear someone say evolution is just a theory. They don't understand what it takes to get to the next step beyond theory (law). Let me go back a hundred years... This guy named Einstein proposed that Newton's Laws of Motion may be incomplete when the numbers get reallllllllly big. Turns out he was right. Well, the scientific community felt a great amount of embarassment that something they had accepted as law was flawed. Since then, pretty much nothing has become a law, just in case it gets proved wrong.
So, evolution is a theory because that's pretty much as far up the ladder as things go these days!!! Not because the scientific community isn't quite sure. What most people think of as a theory (a conjecture that hasn't been thoroughly tested yet) is really called a hypothesis in the scientific community.
Read here rof a second opinion http://wilstar.com/theories.htm
Einstein did not disprove Newtonian mechanics. He showed they work only in a limited (but very broad) range of physical situations, and showed how to extend physics beyond that case.
"Long run is a misleading guide to current affairs. In the long run we are all dead." (John Maynard Keynes)
Evolution and speciation has been observed (both in the fossil record and in the present day). These are the phenomena.
2. Formulation of an hypothesis to explain the phenomena. In physics, the hypothesis often takes the form of a causal mechanism or a mathematical relation.
Natural selection is the hypothesis to explain the observed phenomena.
3. Use of the hypothesis to predict the existence of other phenomena, or to predict quantitatively the results of new observations.
The natural selection hypothesis has been used to predict what kinds of new discoveries we should expect to find in the fossil record, and to predict how controlled breeding programs are likely to turn out.
4. Performance of experimental tests of the predictions by several independent experimenters and properly performed experiments.
Many paleontologists over the years have discovered new "intermediate" forms, as predicted by natural selection. Animal and plant breeders have been independently experimentally verifying the mechanism of selection ("artificial" in this case, but the principle is the same - any controlled experiment is necessarily "artificial") in the evolution of species for a very long time now.
As I said before: evolution, the phenomenon, is an observed fact. A theory of evolution is an attempt to explain the observed fact.
Disclaimer: I am not a creationist.
Ah. Well, as you are neither a creationist your own beliefs, nor, it would seem, are you interested in discussing the actual article...Logic would dictate that you are merely posting deliberately contentious material to stimulate. You are then, by definition, a troll.
Q.E.D.
I get frustrated with evolution being called "just a theory" as ID people try to play semantics. Here's a question - According to the (OT) bible, how many people has god murdered - answer maybe as many as 5 million. How many has satan killed - answer zero (Job's wife and family was killed by satan, but under instruction of god) Wake up all of you - this religion thing is a farse!
Two things:
First, hence the quotes around "disproved".
Second, the AC that also responded to you is right. Newton is never 100% right. However, with the speeds, forces, etc. we experience on a regular basis, Newton is so absurdly close to being correct that it works just as well as Einstien, and the errors that simplification introduces are more or nothing compared to measurement errors.
First two minor points, then I'll get to the real subject, the math of evolution.
theory is a theory my friend
Every field of science is a theory, my friend. Everything from the theory of the atom to the theory of zymosis (that's fermentaion). You may as well try to attack relativity as being "just a theory".
sortof like the unprovable assumption of evolution?????
What unprovable assumption of evolution? Evolution fundamentally says that if if you have heritable variation and mutations and selection pressures on that variation then you will get evolution over generations. This is trivially observable fact. There is no genuine scientific dispute over biological evolution exacly because there is so much evidence that cross checks and cross validates across so many feilds, both current observations and study of prehistorical evidence left behind. Trying to even scratch the surface of this mountain of evidence in this post would be hopeless. If you are questioning the quantity and quality of the evidence, I suggest you either crack open a text book on the subject or at least browse the talkorigins website. It's all well documented if you actually question the issue. If you don't truely question the issue and you instead simply reject the entire subject on non-rational grounds, well obviously you're not going to be swayed by something silly like actual evidence and actual science.
Anyway, the real issue I wanted to address was this one:
the sheer numeric improbability of evolution
Correction, the sheer numeric CERTIANTY. There's powerful mathematics to evolution, powerful effects going on that you don't hear about in the common explanations of evolution. The common idea of evolution is as a sequence of individual beneficial mutations, like climbing a ladder. If that's how evolution actually worked then critics would be right, it would have been mathematically impossible for evolution to produce the incredible complexity we see today.
To show the true mathematical power of evolution I will first abandon that "ladder climbing" of beneficial mutaions. In fact lets assume that every single mutation that occurs is either neutral or harmful. I'll demonstrate that we still get the real and powerful mechanism of evolution, the math of evolution.
A good place to start is with the common complaint of creationists that mutation and evolution "cannot create information". Well in the initial mutation phase they are right. When a mutation occurs it introduces noise, it tends to degrade information. But look what happens the moment that mutation gets passed on to an offspring. That mutation is now no longer random noise, it now carries a small bit on information. It carries a little tag saying "this is a nonfatal mutation". The presence of this mutation in the offspring is new and created information, the discovery and living record of a new nonfatal mutation. Over time the population builds up a LIBRARY of nonfatal mutations. This library is a vast accumulation of new information.
That information actually undergoes even more processing and synthesis. Over generations beneficial mutations would obviously multiply, but we're assuming there are none of those here. However entirely neutral mutations will also tend to accumulate and multiply. Nearly harmless mutations would also accumulate and multiply to a lesser extent. Somewhat harmful mutations will even accumulate, and extremely harmful-but-nonfatal mutations will pop up and disappear at the rarest frequencies. So not only do we build up a library of nonfatal mutations, the mutations get tagged with a tagged with a frequency, the percentage of the population carrying that mutation. Each mutation is tagged with a measurement. Every mutation now carries a cost/benefit information tag at the population level. The best ones have a high percentage representation and the most harmful ones have a near
- - You can't take something off the Internet! That's like trying to take pee out of a swimming pool.
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http://www.amazon.com/exec/obidos/tg/sim-explorer
For an excellent run down on evolution.
Btw... I think this book shows clearly that evolution is _not_ a theory.
One of the more interesting expirements conducted was with tropical fish in South America. More or less there are several species of small river fish. Higher up the mountain the fish are striped, lower down the fish are spotted.
A scientist introduced fish from the bottom (spotted) of one river into the top of another river that had none of these fish. They watched and observed and over time... lo and behold... at the top of the new river there where stripped fish, and at the bottom spotted fish.
The utility of stripe vs spots is attributed to effectiveness of camoflage. At the top of the river, in mountainous terrain, strips work better (overhead foilage is rare). At the bottom of the river spots work better (overhead foilage is common).
There were also some very interest graphs, though without the supporting math, that illustrates a correlation between resource availability (food and water) and speciation (this pertained specifically to finches).
Anyways it was an excellent read (won a pulitzer).
For your specific points, these are very common questions / issues from creationists and others (except the bone question), so the Index is useful:
"Unfortunately, many people (many of them calling themselves scientists) would argue that 'its a waste of time' because 'obviously intelligent design is just wrong'. Not very scientific eh."
You are obviously very unfamiliar with the arguments to keep Intelligent Design out of science classes. "Right" and "wrong," as concepts, are topics for religion, not science. Science is about "supported" and "unsupported" by evidence. I haven't heard scientists say it's "just wrong", I've heard them say its unscientific. Even if Intelligent Design is 100% correct, it would STILL be unscientific-- it would just show that science is unable to explain everything.
There are no "facts" in science, only observations and conclusions. Every testable explanation is a "theory", so saying something is "only a theory" is the scientific equivalent of saying something is "only an explanation that can be tested". Casting intentional doubt on science for the sole purpose of promoting religion is really hurting this country, I think.
The bottom line is that Intelligent Design is not "falsifiable"-- there is no experiment you can use to discredit it, since any result of any experiment can be explained by saying "God/Aliens wanted it that way." You say that the "true scientist withholds judgement until the experiments have been done," which is a good sentiment. However, now that vast numbers of experiments/observations HAVE been done, many scientists are justified in defending evolution. And if anyone ever comes up with an experiment that can be done to support/discredit Intelligent Design, it would be a boon to science to perform the experiment, and I'm sure it would make headlines on Slashdot.
E pluribus unum
It's actually even simpler than that: insects, because of their hard exoskeletons, usually moult (or shed their hard body) a couple of times throughout their lives: it's the only way they can grow.
Some insects (e.g. locusts and cockroaches) basically look more adult (bigger, better wings, etc) with each instar (period between moults.) This guys need to act like adults from the time they are hatched (although some species actually have the parents nurse until the offspring are developed enough.)
For insects laid on carrion, ripe fruit, edible plants, and other transient food sources, time is of the essence: hatch fast, be a sac with a mouth, eat all you can, then pupate and get to the complex, energy-expensive adult stage in one moult.
Note that simple cocoons are nothing more than hardened/dried outer skin - it's just a moult.
Once humans stop natural selection and start applying our own standards of selection, camoflauge becomes a neutral trait: we, not camoflauge, protect the flock or the field.
Probably. But an excellent book about such topics is Song of the Dodo, by David Quammen. In it he writes about island biogeography and examines what happens evolutionarily when species are cut off from the main group. It's a fascinating and fun read and includes details both about Darwin and Alfred Wallace, who may have beaten Darwin to the punch in actuality.
http://www.rootstrikers.org/
My favorite refutation of the bogus Second Law criticism is a seed in some soil in a terrarium. You add nothing but maximally-entropic hydrogen and oxygen in the form of water, maximally-entropic carbon and oxygen in the form of CO2, and sunlight. The seed will sprout and proceed to reduce the entropy of those raw materials in its own growth. The fundies who assert the 2nd Law don't realize that the system creates huge amounts of entropy; it's just leaving in the form of the ~300K waste heat that was once the 5700K solar blackbody spectrum.
Time is Nature's way of keeping everything from happening at once... the bitch.
Evolutionary Biologists have long known some of the mechanisms of speciation. And any freshman in any college intro to Population Biology class knows these quite well...
For instance, one of these mechanisms is spatial segregation, in which some members of a single population become physically separated from another group of that population, by some phenomenon (think changing tidal patterns/river flow paths). This physical separation causes reproductive segregation/separation that leads to speciation by non-shared mutation.
Another is behavioral segregation, which has been mentioned in this thread (orcas hunting fish vs hunting mammals), which leads to social exclusion and, again, reproductive segregation.
Finally, there is selective segregation, which refers to segregation of members of a population due to proficiency at some task necessary for survival. For instance, the Darwin Finches of the Galapagos Islands are under quite strong selective pressure surrounding the size and shape of their beaks. Some finches with long and thin beaks are able to feed on fruit that has small holes in the fruit body, while other members of the same species have larger and stronger beaks that they may use to crack open other kinds of seeds. When food is plentiful, both phenotypes are able to get along just fine on seeds and fruits that lie inbetween these extremes, but when selective pressure is applied (in the form of a famine, perhaps), this small phenotypic difference in beak size/shape results in survival for these two, now more genetically distinct, genotypes, while those finches that fall inbetween the two extremes tend to not survive. If such a selective pressure (famine) lasts for long enough, the two resultant populations may achieve speciation. All of these mechanisms have something in common, they all require reproductive segregation of some sort. This research is all at least 10 years old, and this article is just scientific fluff.
For an extremely interesting and pertinent read, try The Beak of the Finch: A Story of Evolution in Our Time by Jonathan Weiner.
They absolutely misobserved the experiment. Because whether at the Parthenon or somewhere else the same distance from the earth, all objects fall at about 9.8 m/s.
That is so very false that I am baffled. For starters I think you mean that acceleration due to gravity is about 9.8 merters per second squared. That's acceleration, not velocity.
And indeed a feather and a stone will always accelerate at identical rates. Their maximal or terminal velocities may differ significantly however, as the maximum velocity that can attain is determined by the amount of resistance they recieve from the medium they are falling though. A feather receives far more resistance in air than a rock, and hence has a much lower terminal velocity and may reach the ground later. The acceleration is the same, but the velocity is different. For somethign different try changing the medium instead of the object: drop a stone in air, and for the same distance through water. The water provides more resistance so the stone will have a lower maximum velocity in water and hence will fall more slowly.
HTH.
Jedidiah.
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You have no idea what you're talking about re: mutations. They are very, very numerous and common.
http://www.iscr.ed.ac.uk/mecp2/mutations.php (random result of web search. First one I looked at.)
And, how does one underestimate a fact? More like, never underestimate people's ignorance about biology.
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Those who say a scientific theory is "just a theory" generally do so because they don't actually know what a theory is. They understand a theory to be a guess or a hunch (that's a hypothesis not a theory).
In science, a theory isn't a guess or a hunch - it's something a great deal stronger than that. A scientific theory makes testable predictions that can be verified by observation.
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"An intelligent designer would create intelligent designs, with each feature designed perfectly to fit its intended purpose."
This is assuming a perfect creation. Evolution is full of metaphysical assumptions, but pretends its not. See Darwin's God: Evolution and the Problem of Evil. His main point is that the biggest problem of evolution is not its metaphysics, but its denial of its metaphysics.
Anyway, let's look at some flaws in your assumptions:
1) God would make each creature perfect. In fact, God specifically said he made some creatures persue folly by design.
2) Each creature currently is as it was created. Would not a good engineer make a creature adaptable?
3) Each creatures is as perfect as was originally made. But Biblically, all creation was affected by the fall.
It sounds like your arguments are from Gould. Gould was a great writer and an excellent thinker, but he failed to see (or even possibly know about) how the fall would affect biology. Understanding the Pattern of Life has a great chapters on both biodiversity and biological imperfection. While it probably isn't enough to convince a skeptic, it would probably be useful for skeptics to at least understand the creationist perspective.
Most people also don't understand that both creationists and evolutionists believe in evolution, the main difference being that creationists believe in a polyphyletic tree, and that biodiversity was built-in while evolutionists think that it was not built in.
Engineering and the Ultimate
I am not suggesting that your beliefs are wrong or invalid. I suggest that we speaking about them, that you delineate belief from knowledge, without implying that one is inferior to the other. In fact, one can say that knowledge is inferior because it is composed of possibly flawed conclusions drawn from a limited number of observations, whereas beliefs (and Faith) are pure, perfect, universal, and irrefutable. So keep your superior beliefs out of inferior Science (and vice versa). This point is especially valid when discussing ID, because Christian Fundamentalists want their beliefs taught as knowledge in Science classes.
Science is about knowledge, not Truth or Belief or Answers. The state of Science at any given moment is basically: these are the few things that we know, and here are the observations (direct or indirect) that cause us to know them. And BTW, please show us that the conclusions that we have drawn from these observation are incorrect, because that is the means by which our knowledge grows in both quantity and quality.
Censorship is telling a man he can't have a steak just because a baby can't chew it. --Mark Twain
Is there any way to falsify the evolution theory?
many, many ways
The 'wrong wiring' acts as a filter, which among other things lets humans see under much brighter conditions than a squid, which lives in the water (where there is less light).
This is dumb. We have an adjustable pupil in our eye as well as photoreceptors that adapt to light. The tiny bit of light absorbed by the layer of cells at the back of the retina does not help at all. All it does is scatter the light a bit and reduce visual acuity.
It also acts as a UV-filter, which squids living under water, don't need.
Wrong again. Those cells are virtually transparent to UV and provide no appreciable protection. As a matter of fact, birds, who have the same eye design as we do, can see UV. Besides, those cells are neurons that are required to see. They are the cells that need to be protected from UV. So having them absorb UV would be exactly the wrong thing to do if you were trying to design an eye.
Furthermore, the blind spot costs us nothing, since we have two eyes(=most of the time the blind spots don't overlap), and (unless we focus them) they are moving constantly, so nothing can hide in the blind spots.
But why have a blind spot at all? Yes, we've adapted so that they are only rarely a problem. But an object coming at you rapidly from your blind spot could put out your eye because you wouldn't see it coming to blink. And if you lose one eye, which is not that uncommon an injury in the wild, you will be even more vulnerable. It provides no conceivable advantage; no intelligently designed light sensor runs the wiring in front of the sensors.
I have to say that there clearly is a misunderstanding of evolution by either the reporter or the scientists; most likely the reporter. Species are not defined by their inability to reproduce. That is a creationist myth that somehow got accepted as being connected with evolution. Darwin saw it differently. First, start with variations in animals. Variations like long ears and short ears are defined as animals living today where "steps" linking the two animals can be found still living. Between the short ear and the long ear can be found not so short eared, medium length eared, and not so long eared, etc. That is variation. Species are linked not by "steps" living today but by "steps" in the fossil record. Today you would only find long eared and short eared and nothing in between. Only when you dig into the fossil records do have a hope of finding the lost "steps". Remember that only a small insignificant amount of creatures get fossilized and are found by us. The rest are lost to us. So once again variation is separated by space and species are separated by time. Whether the long eared and the short eared can mate together is also a matter of a gradient from full fertility to zero fertility of individual animals; not a cliff like separation. Every once in a while (every seventy years or so) you hear stories about a mule that gives birth. Can a giraffe and a fish mate? No, because the divergence of the two in time is so great that their reproductive systems are incompatible. Can a zebra and a horse mate? Yes, but with extreme difficulty and is dependent on finding two individual animals that can mate; i.e. less variations between the two in the reproductive area. Can coyotes and wolves mate? Yes, and it seems to be happening more and more to the point where the grey wolf will be replaced entirely by a new type of animal that is a mixture of wolf and coyote.
That's called polyandry, not polygamy...
Yep. Search for 'XXX chromosome'; returns no porn on front page, and this in the first 10 results: http://www.med.umich.edu/1libr/yourchild/xxxsyn.ht m
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What about the evolution of the eye?
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