Advantages of living in the dark: The multiple evolution events of 'blind' cavefish

Jan 22, 2012
This is the blind Mexican cavefish (Astyanax mexicanus) along with its sighted cousin the Mexican tetra. Credit: Professor Richard Borowsky

The blind Mexican cavefish (Astyanax mexicanus) have not only lost their sight but have adapted to perpetual darkness by also losing their pigment (albinism) and having altered sleep patterns. New research published in BioMed Central's open access journal BMC Evolutionary Biology shows that the cavefish are an example of convergent evolution, with several populations repeatedly, and independently, losing their sight and pigmentation.

The and the surface dwelling Mexican tetra, despite appearances, are the same species and can interbreed. The cavefish are simply a variant of the Mexican tetra, albeit one adapted to living in complete darkness. A team of researchers from Portugal, America, and Mexico studied the DNA from 11 populations of cavefish (from three geographic regions) and 10 populations of their surface dwelling cousins to help understand the of the physical differences between them.

While results from the genotyping showed that the surface populations were genetically very similar, the story for the cave populations was very different. The cave forms had a much lower , probably as a result of limited space and food. Not surprisingly the cave populations with the most influx from the surface had the highest diversity. In fact there seemed to be a great deal of migration in both directions.

It has been thought that historically at least two groups of fish lived in the rivers of Sierra de El Abra, Mexico. One group originally colonized the caves, but became extinct on the surface. A different population then restocked the rivers and also invaded the caves.

Prof Richard Borowsky, from the Cave Biology Group at New York University explained, "We were fortunate in being able to use A. mexicanus as a kind of 'natural' experiment where nature has already provided the crosses and isolation events between populations for us. Our results have provided evidence that the cave variant had at least five separate evolutionary origins from these two ancestral stocks."

Dr Martina Bradic who lead the research continued, "Despite interbreeding and gene flow from the surface populations the eyeless 'cave phenotype' has been maintained in the caves. This indicates that there must be strong selection pressure against eyes in the cave environment. Whatever the advantage of the eyeless condition, it may explain why different populations of A. mexicanus cave fish have independently evolved the same eyeless condition, a striking example of convergent evolution."

Explore further: Florida lizards evolve rapidly, within 15 years and 20 generations

More information: Gene flow and population structure in the Mexican blind cavefish complex (Astyanax mexicanus) Martina Bradic, Peter Beerli, Francisco García-de León, Sarai Esquivel-Bobadilla and Richard Borowsky BMC Evolutionary Biology (in press).

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jsa09
4.3 / 5 (6) Jan 22, 2012
This article highlights those very points that the creationists are always harping about. Visual evidence of actual evolution in the current environment. But perhaps I give them too much credit. After all I suppose an "intelligence" could have put these fish into the caves and removed the eyes for some reason known only to you know who. And done it more than once.
davhaywood
4.3 / 5 (6) Jan 23, 2012
Aaaaand cue the creationist claptrap!
Telekinetic
not rated yet Jan 23, 2012
What about a seeing-eye crab?
Telekinetic
5 / 5 (1) Jan 23, 2012
Seeing-eye crab.
julianpenrod
1 / 5 (7) Jan 23, 2012
So carelessly "evolutionists" toss off the idea of lack of eyes and color being "selected for". At the same time tossing away the primary Darwinian premise that the "selection" is purely oin the basis of providing a survival advantage, and, for that matter, secondarily, that the adaptation has to be in line with a change that is natural and normal, within the simplistic developmental purview of the creature. And note the carelessly dismissive "explanation" that "evolution" provides, namely, "there must be a strong selection against eyes in the cave environment", "whatever that may be". Those who accept the presence of God say, "He has His reasons" for what happens, and note how "scientists" and their defenders howl at that! Yet, here, "evolution" is saying, "Well, there has to be an 'evolutionary' reason, there just has to, because you are not allowed to think that anything other than 'evolution' exists! Even if we never find it, there has to be an 'evolutionary' reason!"
julianpenrod
1 / 5 (7) Jan 23, 2012
To be sure, some shills casually, and dutifully, toss off the "explanation", "Well, having eyes and color requires energy and not having them saves the animal energy." But any energy savings there would be at best minimal. And that small an advantage is not a decisive advantage at all. And, consider, if having color puts such an energy demand on a creature, why don't creatures in lighted environments have color? Certainly, cavefish can find mates and defend their territory well enough without it, so why does it exist in the non-pellucid world?
Deathclock
4 / 5 (8) Jan 23, 2012
To be sure, some shills casually, and dutifully, toss off the "explanation", "Well, having eyes and color requires energy and not having them saves the animal energy." But any energy savings there would be at best minimal. And that small an advantage is not a decisive advantage at all.


It doesn't matter, the tiniest statistical advantage over billions or trillions of generations produces a trend toward that advantage.

Eyes are useless in complete darkness, and not only do they save energy but also if the eye can become diseased or infected and cause death it is definitively advantageous to not have them. You don't seem to understand that in the wild most organisms are on the verge of starvation ALL THE TIME. Any way to make the little bit of energy you are able to acquire last longer and go further is important.
julianpenrod
1 / 5 (8) Jan 23, 2012
Deathclock says "the tiniest statistical advantage over billions or trillions of generations produces a trend toward that advantage." But, an infinitesimally small advantage, one that would take "trillions of generations" to turn into a recognizable characteristic, is so minute it would not produce an advantage. Especially when it is considered that the world frequently changes more, from minute to minute, than that tiny "advantage". Also, a single small mutation is not an advantage since the creature likely will not have the necessary additional physical characteristics or instincts to take advantage of it. If means of seeing mates declined, senses to locate them otherwise didn't automatically kick in to start evolving.
And a cheetah that can reach 60 miles per hour, or a springbok jumping higher than a man, is not an easy way to "argue" that asnimals are all just shy of starving.
It's amazing how little those devoted to "evolution" actually are aware of its rules.
Telekinetic
5 / 5 (6) Jan 23, 2012
I'm with Reverend Penrod on this one. These fish went blind from masturbating.
julianpenrod
1 / 5 (6) Jan 23, 2012
Note, too, the assertion in the article of "multiple evolutions". They seem to be saying that, on five separate occasions, populations of tetra went from the above ground world to the cave world and these later incursions into the pellucid environment evoled exactly the same as the fish that went in first! In other words, underwent exactly the same mutations, directed in exactly the same way, bestowing exactly the same response to conditions. This sounds more like Lamarckianism than Darwinism, a result oriented change rather than the result of random influences.
And notice something else. Defenders of "evolution" say that losing color and eyes bestows a small but significant extra energy that made them compete successfully to survive. Then how could each successive influx of fish survive? The later fish will be sighted and colored, competing with the supposedly more energetic blind and colorless fish! How did these later fish survive to evolve?
davhaywood
5 / 5 (4) Jan 24, 2012
They didn't have to survive to evolve. The influx of fish from the surface allowed enough opportunities for surface fish to mate with the cave-dwellers, since as they said in the article, they are the same species and can therefor mate. When two individuals mate, genetic information from each parent is then shared with the progeny. The fish from surface to cave and visa versa didn't need to survive indefinitely -- only long enough to transmit their genetic material, all of which may or may not be selected for but will still be present in the genome of later generations, even in only a vestigial capacity. It's not as if when they pass from their accustomed environment to the other that they immediately die, but their traits will be at a disadvantage in the long run. Hope I explained it well enough for you to understand Julian. By the way, how many science forums do you troll? This is the second one I've seen you on.
Deathclock
3.4 / 5 (5) Jan 24, 2012
But, an infinitesimally small advantage


It's not infinitesimally small...

one that would take "trillions of generations" to turn into a recognizable characteristic


It didn't necessarily take that long...

is so minute it would not produce an advantage.


You defined it as an advantage... a small one but an advantage none the less, so yes an advantage would produce an advantage...

Especially when it is considered that the world frequently changes more, from minute to minute, than that tiny "advantage".


That advantage can remain an advantage across unrelated changes to the environment.

Also, a single small mutation is not an advantage since the creature likely will not have the necessary additional physical characteristics or instincts to take advantage of it


False, not having eyes is not having eyes. From the fishes point of view having eyes in complete blackness all the time is equivalent to not having eyes, no extra instinct is required.

cont
Deathclock
3.7 / 5 (6) Jan 24, 2012
If means of seeing mates declined, senses to locate them otherwise didn't automatically kick in to start evolving.


You can't see mates in the dark, and for fish and many other animals sight is not the primary sense to navigate their environment.

And a cheetah that can reach 60 miles per hour, or a springbok jumping higher than a man, is not an easy way to "argue" that asnimals are all just shy of starving.


Of course it is, for the cheetah it is the primary means of acquiring food and for the springbok it is the primary means of not becoming food.

It's amazing how little those devoted to "evolution" actually are aware of its rules.


You have no idea what you are talking about, I studied evolutionary biology formally at CMU, I have written practical genetic algorithms to solve optimization problems. Your statements make you appear foolish, or at least ignorant of evolutionary theory.
Deathclock
3.9 / 5 (7) Jan 24, 2012
Note, too, the assertion in the article of "multiple evolutions". They seem to be saying that, on five separate occasions, populations of tetra went from the above ground world to the cave world and these later incursions into the pellucid environment evoled exactly the same as the fish that went in first! In other words, underwent exactly the same mutations, directed in exactly the same way, bestowing exactly the same response to conditions. This sounds more like Lamarckianism than Darwinism


Because you have no idea what you are talking about. The same mutations occur constantly, in all species. The same mutations occur in humans over and over and over again and have for hundreds of years. Of course most mutations are detrimental, as would be the lack of eyes EXCEPT when the fish were living in the cave. It makes complete sense that this mutation would be selected for in the cave and selected against outside of it.

Again, you don't know what you are talking about.
Deathclock
3 / 5 (4) Jan 24, 2012
As an aside, most people on here have no idea what they are talking about when it comes to evolutionary theory. I suggest if you haven't received formal education at an accredited university you keep your big mouth shut because you are probably making a fool out of yourself.

More importantly, look up Dunning-Kruger syndrome and consider that if you speak authoritatively about a technical topic with no formal education pertaining to that topic this syndrome just might apply to you.
Deathclock
3.7 / 5 (6) Jan 24, 2012
In other words, underwent exactly the same mutations, directed in exactly the same way, bestowing exactly the same response to conditions. This sounds more like Lamarckianism than Darwinism


This all the evidence anyone needs to realize that this penrod clown doesn't know anything about evolutionary theory.

The same mutations occur over and over again... ever heard of genetic diseases in humans? Here is a list of hundreds of them that occur repeatedly in humans:

http://en.wikiped...isorders

...and yes, these are detrimental mutations, but whether a mutation is beneficial or detrimental depends on the environment. Under the right conditions a mutation could be either, and that is what is happening with these fish. Outside of the cave where there is light this lack of eyes is a detrimental mutation, inside the cave where it is pitch black it is an advantageous mutation... selection takes over accordingly.

Deathclock
1 / 5 (1) Jan 24, 2012
Aww... penrod doesn't want to play anymore...
davhaywood
not rated yet Jan 24, 2012
He never does once he loses, but somehow will never admit defeat and reformulate his views. A troll of the highest order. For more of Mr. Penrod, you can go to 13.7 Cosmos and Culture on NPR.org.
gwargh
5 / 5 (3) Jan 25, 2012
They seem to be saying that, on five separate occasions, populations of tetra went from the above ground world to the cave world and these later incursions into the pellucid environment evoled exactly the same as the fish that went in first! In other words, underwent exactly the same mutations, directed in exactly the same way, bestowing exactly the same response to conditions.

While DC is right in saying the same mutations could occur, that's not even what this article is saying.
The scientists are talking about the same effects. That is, the mutations led to the same phenotype (non-functional eyes, albinism), but it is precisely because the mutations are different that we can tell there were 5 separate events. So, in one population a G could have changed to a C and removed carotenoid processing form the fish (which would also remove pigmentation btw), while in another retinal development is dsiturbed. Same phenotypes, different mutations.
julianpenrod
1 / 5 (4) Jan 25, 2012
The article itself says that each population of tetra "independently evolved" into cavefish, in "at least five separate evolutionary origins", supposedly demonstrating "convergent evolution". Meaning the tetra's own breeding among their own kind, with "favorable mutations" arising, caused them to devlop along exactly the same path as the cavefish. Yet dayhaywood, with their supposed greater grasp of the issue, described the fish interbreeding and those in the caves taking on traits of the cavefish that way. An example of a technique of davhaywood in "proving" their point, namely, not proving it and insisting they did! Just another case of doggerel.
Deathclock
1 / 5 (1) Jan 25, 2012
While DC is right in saying the same mutations could occur, that's not even what this article is saying.
The scientists are talking about the same effects. That is, the mutations led to the same phenotype (non-functional eyes, albinism), but it is precisely because the mutations are different that we can tell there were 5 separate events. So, in one population a G could have changed to a C and removed carotenoid processing form the fish (which would also remove pigmentation btw), while in another retinal development is dsiturbed. Same phenotypes, different mutations.


Interesting, I should have read the article more closely.

Regardless, it doesn't change my criticism of Penrods statements.
julianpenrod
1 / 5 (3) Jan 25, 2012
Deathclock said animals are always on the verge of starvation and I asked how a starving cheetah could run at 60 miles per hour. Deathclock replied that's "its primary means of acquiring food". Which doesn't explain how they manage that if they're "starving", but, then, Deathclock "proves" their point by not proving it and insisting they did.
And, if you accept Darwin, then the mutations are infinitesimally small, accumulating over centuries. Remember, too, the mutations must also breed true, they can't be like albinism, they supposedly must be so small they don't interfere with the breeding process the way massive changes often if not always do.
Deathclock
2.3 / 5 (3) Jan 25, 2012
Deathclock said animals are always on the verge of starvation and I asked how a starving cheetah could run at 60 miles per hour. Deathclock replied that's "its primary means of acquiring food". Which doesn't explain how they manage that if they're "starving", but, then, Deathclock "proves" their point by not proving it and insisting they did.


Really? I didn't say they were always starving.. Is this the best you can do?

And, if you accept Darwin, then the mutations are infinitesimally small, accumulating over centuries.


I'd like to know what Darwin has to do with this... Darwin is credited with the initial idea, but what we know now goes FAR beyond what he knew... with all due respect.

Also, this statement is false, single mutations can create significant changes.
julianpenrod
1 / 5 (4) Jan 25, 2012
And, with respect to mutations causing diseases repeartedly, those aren't mutations, as such. They are changes that occur in areas of the genome structure in areas apparently already prone to variation in meiosis. The mutations Darwin spoke of were changes in any area not just vulnerable ones. If changes were as constant and repetitive as Deathclock requires for their assertions to be true, there would be no such thing even as a normally definable genome! And the list of such repetivie mutation diseases would have millions and millions of entries, one for each gene.
Deathclock
3 / 5 (4) Jan 25, 2012
And, with respect to mutations causing diseases repeartedly, those aren't mutations, as such. They are changes that occur in areas of the genome structure in areas apparently already prone to variation in meiosis. The mutations Darwin spoke of were changes in any area not just vulnerable ones.


Pulling shit out of your ass... they are mutations like any other. Point mutations, insertions, deletions, etc.

If changes were as constant and repetitive as Deathclock requires for their assertions to be true, there would be no such thing even as a normally definable genome! And the list of such repetivie mutation diseases would have millions and millions of entries, one for each gene.


Completely false, there is no reason to assume that any particular mutation will cause a noticeable effect. The mutations on that list are the particularly nasty ones, because they naturally receive the most attention. Most will have little if any obvious effect.
julianpenrod
1 / 5 (4) Jan 25, 2012
Being "on the verge of starvation" is no different significantly from starvation. How can an animal so poorly nourished that the term "starvation" can be associated with them run at 60 miles per hour?
And Darwin does have a place in this, since the rule being promoted is that of random mutation changes creating manifestations that build up over time. As with so many who have no legitimate gripe, Deathclock just finds fault with everything I do.
And, since the discussion here is about Darwinian "evolution" supposedly producing workable new features, only changes that produce viable manifestations, that don't represent fatal conditions for the creature, are under consideration. Yes, mutations can cause significant changes, but they are supposedly not coordinated to occur in areas where an entire feature will be altered in a usable manner. There is no record anywhere of a single mutation, in one generation, producing a feasible improvement in the creature's make-up.
Deathclock
3 / 5 (4) Jan 25, 2012
Being "on the verge of starvation" is no different significantly from starvation.


I'm not going to argue semantics with you

And Darwin does have a place in this, since the rule being promoted is that of random mutation changes creating manifestations that build up over time.


My point is MODERN evolutionary theory is a far cry from Darwin's original understanding. It always seems like most people arguing against evolution are under the false assumption that our knowledge ended with Darwin's original theory, which is obviously not the case.
julianpenrod
1 / 5 (5) Jan 25, 2012
If you talk about mutations having small effects, Deathclock insists on talking about those that suppoedly have big effects, if you mention the idea of mutations having big effects, Deathclock talks about mutations having small effects. Deatchclock mentions mutations so small they would take "millions or trillions of generations" to express themselves, then, when I also speak of "trillions of generations, Deathclock spouts that it wouldn't necessarily take that long. Deathclock talks about animals being so poorly nourished they are "on the verge of starvation". where even a miniscule difference in energy can make a difference, and Deathclock will say they weren't talking about the anima actually "starving". Another of their techniques for promoting their cause, literally, nattering; quibbling about fine points of p[hraseology, refusing to see what they mean or about items that, in the end don't really make a difference; disagreeing with everything; always changing the topic.
Deathclock
3.7 / 5 (6) Jan 25, 2012
There is no record anywhere of a single mutation, in one generation, producing a feasible improvement in the creature's make-up.


The telomere-telomere fusion of two ancestral chromosomes into human chromosome number 2 is a pretty damn good example.
Deathclock
3.4 / 5 (5) Jan 25, 2012
If you talk about mutations having small effects, Deathclock insists on talking about those that suppoedly have big effects, if you mention the idea of mutations having big effects, Deathclock talks about mutations having small effects.


Yes, mutations can have both significant and insignificant effects on the phenotype... is this news to you?

Deatchclock mentions mutations so small they would take "millions or trillions of generations"


Nope, a mutation occurs in a single generation, I was talking about a specific change to the phenotype.

Another of their techniques for promoting their cause, literally, nattering; quibbling about fine points of p[hraseology, refusing to see what they mean or about items that, in the end don't really make a difference; disagreeing with everything; always changing the topic


I guess one giant ad hominem is preferable?

Also, you seem to be under the impression that mutations can take more than one generation... they cannot.
Deathclock
3.4 / 5 (5) Jan 25, 2012
There is no record anywhere of a single mutation, in one generation, producing...


All mutations occur in a single generation... you clearly don't even know the BASICS of what you are talking about.
julianpenrod
1 / 5 (4) Jan 25, 2012
Incidentally, notice how, after 20 hours of inaction, there "just happens to be" a comment placed by "gwargh" "just in time" to precede mine, also pointing out that the article was talking about five supposed independent evolutions, not sighted tetra mating with blind cavefish and producing offspring. In this way, Deathclock can admit not even knowing what the suibject of the article they were commenting on was to "gwargh", but not to me. Incidentally, notice, too, it was davhaywood who specifically said the fish interbred, not Deathclock. Is Deathclock davhaywood? If you look up "gwargh's" comment,s you'll find "they" are listed as commenting avery few days up until July 2011, then nothing, until now, when they can allow Deathclock to admit their not even knowing what they're talking about to someone other than me.
julianpenrod
1 / 5 (3) Jan 25, 2012
Note the characteristic taking issue with my mentioning a mutation in a single generation causing a noticeable improvement. First, there is no sign of actual necessary improvement due to the claimed joining of two chromosomes to make human chromosome 2. Also, Deathclock finds it necessary to object to part of the sentence as if it were the whole sentence, suggesting that I don't realize that mutations can express themselves in a single generation.
Like, in the end, someone who says, "Aww...penrod doesn't want to play anymore..." can necessarily be trusted to be sincere and not just treating the issue like a game. By their own words Deathclock indicates they weren't serious, they toss out disclaimers just to try to derail legitimate discussion.
Deathclock
3 / 5 (4) Jan 25, 2012
Incidentally, notice how, after 20 hours of inaction, there "just happens to be" a comment placed by "gwargh" "just in time" to precede mine, also pointing out that the article was talking about five supposed independent evolutions, not sighted tetra mating with blind cavefish and producing offspring. In this way, Deathclock can admit not even knowing what the suibject of the article they were commenting on was to "gwargh", but not to me. Incidentally, notice, too, it was davhaywood who specifically said the fish interbred, not Deathclock. Is Deathclock davhaywood? If you look up "gwargh's" comment,s you'll find "they" are listed as commenting avery few days up until July 2011, then nothing, until now, when they can allow Deathclock to admit their not even knowing what they're talking about to someone other than me.


Wow... go ahead and ask the website administrators about it if you're so paranoid.
Deathclock
3 / 5 (4) Jan 25, 2012
Note the characteristic taking issue with my mentioning a mutation in a single generation causing a noticeable improvement. First, there is no sign of actual necessary improvement due to the claimed joining of two chromosomes to make human chromosome 2.


You don't even know what I was referring to, do you? That fusion represents the significant difference between the modern great apes and humans. That fusion caused a weakening of a jaw muscle. The weaker jaw muscle, attached to a skull plate, allowed that plate to expand further in adolescence before fusing with the other skull plates, making room for a larger brain. It explains humans weaker bite force and larger skulls and our intelligence.

You are clueless.

...and are you going to admit that you know nothing about evolution since you somehow thought a single mutation does or can occur over multiple generations? I mean, this shows you don't even know what a mutation is... you've lost, give it up.
julianpenrod
1 / 5 (4) Jan 25, 2012
davhaywood claims that I "don't want to play anymore", once I lose, suggesting that, when my statements were disproved, I just leave petulantly. In fact, in no case where I commented on article did I ever lose, not once were my statements disproved. New World Order shills are paid to stay at the job constantly and peddle lies. I provide the information and, when it is obvious that those promoting the NWO's agenda are not discussing the matter legitimately, I refuse to rise to their bait. The ilk NWP shills seek to attract think that getting the last word "proves" someone is telling the truth.
And, note davhaywood's malignant thinking. davhaywood portrays it as a fault my stopping arguing when purportedly I lose. But, itsn't it a fault to continue to argue when you've been disproved? By their own words, dayhaywood says it is wrong not to continue arguing when you've been proved wrong! Which explains Deathclock and davhaywood's actions!
Deathclock
3 / 5 (4) Jan 25, 2012
Okay, you're clearly a nut, excuse me while I stop wasting my time...

unless of course you want to admit that you know nothing about evolution since you didn't even know what a mutation is (as evident by the fact that you thought a mutation could somehow occur over multiple generations)
gwargh
not rated yet Jan 26, 2012
Haha, clearly I'm some kind of dark puppet account meant to bolster the small (but evil and persistent) forces of the evolutionists. Any other explanation is clearly too simple to be true.

On another note, stop feeding the trolls. They grow big and hairy.
jsa09
not rated yet Jan 26, 2012
Some of us are in different time zones and make comments with little ability to communicate with those that have gone to sleep already. By adding comments out of phase with others may make it more difficult to partake in ongoing discussions.
MarkyMark
not rated yet Jan 26, 2012
Some of us are in different time zones and make comments with little ability to communicate with those that have gone to sleep already. By adding comments out of phase with others may make it more difficult to partake in ongoing discussions.

Problem is that penrod believes the earth is flat!
davhaywood
not rated yet Jan 29, 2012
The article itself says that each population of tetra "independently evolved" into cavefish, in "at least five separate evolutionary origins", supposedly demonstrating "convergent evolution". Meaning the tetra's own breeding among their own kind, with "favorable mutations" arising, caused them to devlop along exactly the same path as the cavefish. Yet dayhaywood, with their supposed greater grasp of the issue, described the fish interbreeding and those in the caves taking on traits of the cavefish that way. An example of a technique of davhaywood in "proving" their point, namely, not proving it and insisting they did! Just another case of doggerel.


Your point doesn't make sense, Julian. In your previous statement you said, "The later fish will be sighted and colored, competing with the supposedly more energetic blind and colorless fish! How did these later fish survive to evolve?" I was simply explaining how genetic information from the surface fish could be present.
davhaywood
not rated yet Jan 29, 2012
You know, I had a well-reasoned, well thought out response to your complaints Julian, but like DC said it is best we stop wasting our time because you will misconstrue and conflate not only what I say, but what is said in the article and by others.

By the way, my point about you ceasing to talk once you lose, but never ADMITTING DEFEAT OR CHANGING YOUR POSITION was what was remarkable. You may discontinue a one specific conversation where you have clearly been outpaced, but you will happily pick up right where you left off in another article, having blissfully expunged any pertinant information from preceeding conversations. Good day, sir. And please stop trolling legitimate scientific discussions, stick to your prayer groups.
adwarakanath
not rated yet Feb 23, 2012
Wow, people with no training in Biology shouldn't even be attempting to discuss biology. That's for you, Rev. Penrod..you know, because unless things are made blatantly clear and obvious, you don't seem to get stuff.

1. Darwin NEVER talked about mutations in the way we understand them today. Just mentioning that itself shows you know jackshit about biology or its history. Darwin only talked about variation and natural selection. Today we know that evolutionary mechanisms include random variation, biased mutations, genetic drift, genetic hitchhiking and gene flow. Some mutations have more of a probability of occurring simply based on the genetic code. Genetic drift can cause neutral mutations to become 'fixed', so to say and give rise to phenotypes. Oh by the way, ever heard of the Baldwin Effect? We also include neo-lamarckism in modern evolutionary theory.
adwarakanath
not rated yet Feb 23, 2012
2. Mutations are not spread out over generations. One mutation will only occur in one generation. Many mutations occur in one generation. For a nucleotide base, let's say C to be replaced by G in whatever way, it only takes one reproduction. C and G are fundamental units (almost; you also have different types of C etc). Of course, you'd know that if you'd actually studied biology. Many mutations can accumulate over generations to provide a significant change to the phenotype. Or not. Both cases are predicted by evolutionary theory.

3. The adaptation of the fishes to no light and the invasion by surface fish is a complex matter for you to understand. How do you not get the fact that if eye-bearing surface fish do go down, their eyes don't matter because its just too dark there?
adwarakanath
not rated yet Feb 23, 2012
3. The great example that Deathclock gave of the energy question can be put more simply to you. It is a question of fitness. There was a study which showed that those male elephants that harbor parasites in their body, have a shorter tusk and therefore are less likely to be selected by a female. That is fitness. Moreover, optimizing energy consumption is important for an organism's survival. Actually, it isn't even a question of optimization; you just need to be good enough and slightly better than the other. Significance of a mutation is a branch of mathematical study that is probably far beyond your ken, Rev. Penrod. There are no absolutes in evolution; only probabilities.
adwarakanath
not rated yet Feb 23, 2012
4. There is not a single record of a single mutation causing significant changes? Well, if you had indeed studied undergraduate biology, nay, high school biology, you'd have been aware of a single mutation giving rise to sickle-cell anaemia that allows many african groups to escape the malarial parasite. Or the fact that in the 50s when mosquitos started becoming resistant to DDT, the resistance was conferred on them by a single mutation.

5. The problem is, you don't get what evolution is. Evolution is not a monkey becoming a man. Or a mouse becoming a horse. Evolution is just a change in allele frequency over generations. Nothing more, nothing less. So you will not see major changes during your lifetime. Speciation has been observed which was probably set into motion millennia ago. We can see that. Bacteria are more helpful that way. They evolve very quickly. And viruses.

You are the missing link. Please evolve.
johnnyrelentless
not rated yet Feb 26, 2012
Never find it? We already know it. Eyes are easily injured, especially when stumbling around in the dark. They also cost the body resources to create and maintain. It is clearly an advantage to lose the eyes in an environment where they are useless anyway.