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Sunday, July 18, 2010

The Evolution Of Fish

10 comments:

highdesert said...

Same old false arguments.

Tiktaalik is a fossil that shows both fish and tetrapod features in its skeleton. Its descendants or the descendants of similar creatures could have lived on the edge of the water, breeding in the water as frogs do and coming out onto land for brief periods.

Good grief, another person talking about the supposed problem of needing one individual of each sex to evolve separately! It is totally ignorant to think that evolution proposes such a need.

Joe Sirianni said...

Same old rebuttal - Tiktaalik is a unique fish. Can you show me the transition where digits were formed in the gradual evolution of this creature? Or whatever the next step was? What did Tiktaalik evolve into? And I still you like using words like "could have" You have always had a difficult time telling the difference between fact and speculation.

And what is ignorant is someone "assuming" that within a single species there evolved separate exact reproductive organs for the opposite sex with absolutely no evidence for it whatsoever. Yes as you have said in the past this IS what evolution teaches. However, your dilemma is now the extreme lack of evidence for such a notion. You're assuming something occurred in the past that doesn't occur today. Aside from A-sexual organisms females need males and vise versa for reproduction. You are veering greatly from science into the realm of speculation and fairy tales


Joe.

highdesert said...

Joe, if you think that's what I said I must have explained it poorly. I'll try again.

Let's say there was a fish which had had a mutation that made it better able to survive out of the water. (I know you don't think mutations work that way, and I know you don't like hypothetical arguments, but try to put up with it for now so I can explain the reproductive idea.)

The fish which had the mutation was a member of a fish species. Its parents belonged to that species. One mutation was probably not enough to make it into a different species. The fish lived in a population of fish, and these fish had both sexes already. Fish have males and females with male and female reproductive organs. This mutation which improved its ability to survive longer out of the water did not chanqe its reproductive abilities.

And the mutation didn't mean that the fish instantly switched from living, breeding, or reproducing in the water to living, breeding, or reproducing on land. It could have spent a little time on land but continued to reproduce in the water. So there was nothing to stop this fish from breeding with a member of the opposite sex in the population in which it lived. There didn't need to be a fish of the opposite sex with the identical mutation because the mutation did not affect its reproductive abilities.

Some of the offspring inherited the mutation. They bred with other fish in the population, either with the mutation or without. After a few generations, if the mutation were not harmful, and especially if it gave a survival advantage, the mutation would have occurred in an increasingly higher percent of the fish population. At every point in time, the transitional fishes could breed with other members of the population in which they lived.
Each mutation had to happen only once in a single fish, not twice, (one in a male fish and one in a female fish). The first fish with the mutation found its mate in the group of fish in which it already lived. It didn't have to find a fish of the opposite sex which by coincidence had had the sajme mutation. It didn't have to breed with another fish that had the mutation. It mated with a fish without the mutation from the population of fish in which it lived, and their offspring that inherited the mujtation started the spread of the mutation into the population.

Joe Sirianni said...

Highdesert,

I have no idea where to even start with this "story"

It seems like to me you would rather operate in the realm of "scenarios" and "it could have happened like this" comments.

Care to use any scientific data or fact?

Do you understand that all you keep doing is presenting stories of how it could have happened. If what you are saying is true and happened then there would be an ample supply of evidence to back it up. We would see millions and millions of transitional fossils showing these alleged mutations.

And there is nothing in science that shows that just because something mutates (which is a loss of information when evolution teaches there must be a gain of information) this does not mean that their offspring will indeed have the same or similar mutations. This is a great stretch of the imagination. You believe all of this with little to no scientific evidence but rather how you think it could have happened.

A scientist would laugh at your comment. It is the most unscientific thing I have ever heard you type yet. Where is the evidence? If you were brought to a court of law and had to defend this argument the case would be dismissed because you would not be able to supply any evidence whatsoever. Bring a bone in if you will and try to prove the animal who that bone belongs to had offspring. Now try to prove it had "different" offspring (mutations)

Wow would/could you do it? You can't. So instead you offer your story of how you think it could have happened. How far will that get you?

Listen to your comment. For years now these statements have been peppered throughout all of your comments

"Lets say there was"
"was probably"
"it could have spent"
"fishes could breed"

Some of your points almost sounded as though you were there personally as you pint point specific things that supposedly happened.

"Some of the offspring inherited the mutation. They bred with other fish in the population, either with the mutation or without. After a few generations, if the mutation were not harmful, and especially if it gave a survival advantage, the mutation would have occurred in an increasingly higher percent of the fish population"

how in the world do you know that this is how it happened?

highdesert said...

It is hard to find the comment link on your new webpage format.

In my comment I wasn't trying to prove anything. I was tryong to give you a picture of how evolution works in contrast to the picture that the maker of that video was trying to give you. When the narrator talked about the male and female fish just happening to come out of the water in the same place at the same time he was giving you a mental picture of how evolution was supposed to work in their vie3w (and how unlikely that would be). So I tried to correct the picture they were giving you. Not to prove anything, but so you would understand the process.

If you need proof that animals with different genetic sequences acn mate and produce offspring, it happens all the time. You and your wife are not twins. Dogs of different breeds can reproduce even when they have obvious structural differences (which means genetic differences). Animals of some closely related species can reproduce under some conditions even if they normally wouldn't: lions and tigers, horses and zebras. Horses can reprodiuce with that ZPolish -named horse species that I can't spell at the moment, even though they have a different number of chromosomes.
I don't have a time machine to go back and observe all the steps in fish mutation and reproduction that led to lan animals. But for this ex0planation of the male and female, i don't have to. It's just the same thing thaT HAPPENS NOW ALL THE TIME. (sorry capslock - I need to leave.
Again, not tryng to prove anything, just trying to explain why the need for a male and female that s4eparately had the same mutation (or whatever the video was proposing) is unneccessary.

highdesert said...

I want to try again to give you an idea of how that video comes across to me. I'm going to make a parallel example from the Bible. this is not to argue about the Bible or convince you of anything, but try to get you to understand the way in which the male-female thing from that video seems so wrong to me.

First, a question: you know the story about the loaves and fishes. Back when i went to church, I got two ideas of what happened. the first was that there was an actual miracle - that many loaves were created in the place of just a few by divine power. the second was that there was no miracle in the supernatural sense, but that there were actually a lot of people in the crowd who had brought along their own food, and by Jesus's teachings and actions they were motivated to share their food with the group. (Or both things could have happened.)

The Bible is unclear on what actually happened - just that they started out with only a few loaves and at the end they had a surplus.

So what's your belief - was there an actual miracle, where bread was created from nothing for the crowd?

I'm going to assume you believe there was an actual miracle by Jesus (although because of what I learned in my church's Sunday school I'm not sure.)

Suppose I make a video about the story of the loaves and fishes. And in the video I say that the loaves and fishes were most likely just extra food brought by the people in the crowd. But I also say in the video that Christians teach that Jesus created the extra loaves and fishes by waving a magic wand.

So you'd probably think I was wrong to think there was no miracle. But wouldn't you also be bothered that I presented your belief incorrectly, and said Jesus had to use a magic wand?
You can't go back and show evidence one way or another, and the Bible is not clear on what happened. But one thing you know for sure is that Christians do not claim that Jesus used a magic wand.

This is what bugs me about the male-female thing. Not only doea the video say evolution didn't happen (parallel to the loaves and fishes being provided by the crowd, instead of through an actual miracle) but also the video says that for evolution to have happened there would have to be this weird thing of the male and female - which is absolutely not what evolutionary biology teaches. (This is a parallel to Jesus and the magic wand.)

Maybe I can't convince you that evolution happened, that's okay, but I surely ought to be able to convince you that evolutionary theory doesn't agree with what the video says about males and females.

Evolution happens in small steps. That's the part I don't think you are seeing.

highdesert said...

You said this:
"And there is nothing in science that shows that just because something mutates (which is a loss of information when evolution teaches there must be a gain of information) this does not mean that their offspring will indeed have the same or similar mutations. "

If the mutation happens in a germline cell, then there is a 50:50 chance that the mutation will be passed to each offspring.
On average half the fish's offspring will inherit the mutation.

highdesert said...

This video has some huge misrepresentations of the current evolutionary and geologic view of the history of the earth. Even if the maker of the video thinks that view is false, he should have presented it correctly. As it is, he is arguing agianst straw man claims.

The video describes a scenario in which a male and a female fish jump out of the sea, "luckily at just the point in time when plants had evolved to produce air for them to breathe".

But the conclusion of evolutionary biology is that oxygen became present in the atmosphere millions of years before the evolution of fish, let alone tetrapods, as a result of the metabolism of a type of archaea or very primitive bacteria - also called cyanobacteria and previously called blue-green algae. (They are not now classified as plants, and never were classified as green plants.)
The suggestion in the video that the evolution of tetrapods from fish was unlikely because there might have been no oxygen is without basis because the oxygen was there long before there were even fish. It seems like the person who wrote the script for this video didn't bother to check his or her facts with even a high school biology textbook.

Equally bad is the suggestion that the plants 'needed to produce breathable air' would not have been able to have been pollinated because the insects had not yet evolved from 'fish to amphibians to reptiles and all life'.

First of all, the archaea (cyanobacteria) had already been responsible for the oxygen atmospphere long before the multicellular land plants had evolved.
Second, there were land plants before the kind of pollinated green plants that we know today had evolved.
Third, many land plants today are self-pollinated or wind-pollinated - there is not an absolute necessity for insects in the early evolution of the green land plants we see today.

But fourth, and most ridiculous was the idea that there wouldn't have been insects at that time because insects evolved from reptiles! This is beyond ignorant.

Seriously, the person who wrote this script is ignorant of even the most basic biology and didn't bother to check his facts.

highdesert said...

The video is biased in its presentation.

Although it says that evolutionary biologists see the transition from water to land as a slow gradual process, it then presents a supposed model that is the opposite of a gradual accumulation of adaptations, the opposite of a gradual change from solely water-dwelling to mostly land-dwelling. It represents the idea of the transition from water to land with the visual image of a single fish JUMPING out of the water and flopping around gasping for air, without any adaptation for land-dwelling.

Then it states that this would be nonsense to thinking people. Well, yes it would be, if that is what evolutionary biology actually proposed! This is another straw-man.

But then, it adds, as if it were an unimportant, maybe unrealistic, afterthought, that it has been proposed that the fish species which began the transition to land were lungfish.
Lungfish IIRC have lungs which are modified swim bladders. They also have gills. They can breath on land or in water because they have both lungs and gills. So no gasping for air is needed.

But instead of just simply stating this possibility, the video focuses on the picture of the kinds of fish most people would be familiar with, fish that only have gills and can't breathe on land and do flop around gasping for air. The video encourages its audience to focus on this false straw-man image of what evolutionary biology proposes, and throws in the actual idea of the possibility of lungfish ancestors in a dismissive way as if it had no merit.
This is biased presentation, an attempt to manipulate the audience not with information but by innuendo.

highdesert said...

Similarly, this video creates a straw man argument when it talks about breeding.
Although it says that evolutionary biologists see the transition from water to land as a slow gradual process, and that evolution comes by way of 'mistakes' (mutations), it then presents a supposed model that is the opposite of a gradual accumulation of adaptations by way of mutations, and the opposite of a gradual change from solely water-dwelling to mostly land-dwelling.

The video asks:
"And what about breeding? Fish need both males and females to reproduce.
So perhaps one of each sex crawled out of the sea.... AND on the same day...
Then, amazingly, the male found the female. they bred, and their successive generations continued to evolve over millions of years."

Again, this is a word picture that has no relation at all to the ideas of evolutionary biology, and it makes no sense.

According to the video, for the evolution of land-dwelling species from fish, two fish just happen to crawl out of the water onto land . And I think the implication is that they live on land permanently after that (like a movie about a shipwrecked man and woman just happening to land on the same desert island).

But how could these two fish survive on land? To survive out of the water they would already have to have adaptations for land-dwelling. These adaptations would not happen in one single event but would be an accumulation of mutations. The way mutations work, each single mutation, if it is not acutely harmful and doesn't prevent reproduction will spread through a population by way of mating within the population. As the mutations are spread through the population, not just one fish but a whole population of fish are over a number of generations accumulating the traits which will let them live at least partially out of the water.

Again I'll point out that many amphibians live lives connected to water and continue to reproduce in water even when they are able to spend time on land. Frogs and salamanders are examples of that. If a transitional fish were able to crawl out of the water, it could just as easily crawl back into the water. It could find food both on land and in the water. It could continue to breed and lay eggs in the water as fish do, and its young could grow up in the water as tadploes do. There is no reason to portray this all-or-nothing view of the water to land transition that is presented in the video. A male fish which crawls onto the bank could crawl right back in the water and find a female back in the water. And because the adaptations for surviving on land would be present in the population of this transitional species, there would not be just a single unusual fish able to crawl onto land - there would be many fish crawling out onto land and back into the water. That this way of life is reasonable we know from current amphibians - it does not have to be all or nothing. No amazing coincidence in time and space is needed! The picture this video paints is completely bogus.


You asked how I could know that was how it happened. Well, of course I don't have a time machine (and neither to you). But this is the way mutations do spread in fish populations now. It happens all the time in research labs and the aquariums of fish hobbyists as well as in the wild. If a mutation occurs which is not seriously harmful and does not prevent reproduction, the fish with the mutation is able to reproduce with a fish of its species which does not have the mutation. Eventually a whole line of fish can be bred with a new mutation. There is no need for an amazing coincidence as portrayed in the video.