Pigeons and Dogs: Micro or Macro evolution?

As started with this link, a discussion arose as to whether how dramatically pigeons have changed through selective breeding indicates that there is no line between microevolution and macroevolution.For example, this:and this:are both decended from a species that looks like this:Now, let's not kid ourselves: what we've witnessed from selective breeding is major morphometry changes in just a few hundred years - including significant skeletal restructuring. So I have to ask: how much change *do* you need to see, and of what kinds, before deciding that something is "macroevolution" instead of "microevolution"? Or is the belief that such dramatic changes, for some reason, could not occur in nature?Additionally: If the only dog "breeds" present today were:and:Why on earth would we not consider them separate species, when we consider:to be separate? The wolf above can interbreed with the malamute (wolf-dog hybrids are known as "wolfdogs"), but the malamute cannot interbreed with the ciuhaua - it would be hard even through artificial insemination to get the fetus to make it to term. The ciuhaua and the malamute effectively cannot interbreed, and have much greater structural differences.Dogs are what is known as a "ring species", in which if the ends existed alone, they would be considered separate species because they have virtually no capability to interbreed, but because of the currently living intermediaries, gene flow is still possible (the same can be seen in a number of birds distributed around the world, where the North American ones can't breed with the European ones, but each can breed with their neighbors).Comments?------------------
"Illuminant light,
illuminate me."

Feel free to stray - I'll hold the admins off for you to the best of my ability hehe------------------
"Illuminant light,
illuminate me."

( drat! They found us! )------------------
"Illuminant light,
illuminate me."

quote:

---

questions about the pictures... 1) where is the first pigeon's head? 2) is that red pigeon puffing it's chest out in some kind of mating ritual or something?

---

The top pigeon is called a fantail; the second pigeon is called a cropper. If you check the link at the top of the page, you'll find some more of the many bizarre breeds of pigeons that people have created. The top one isn't ducking, and the second one isn't puffing out its chest - they're actually physically built that way. Fantails have a head sunken partway into their oversized chest, with a fan of feathers peacock style. Croppers are tall with an enormous round chest.Some of the pigeon changes in history have been "punctuated equilibrium" style, where there was a sudden, fairly dramatic change that people just happened to like. Many others were gradualism, where there was steady movement in a direction that people happened to like.Amazing how dramatically genes can change in just a few hundred years when there's intense enough selective factors, isn't it? ------------------
"Illuminant light,
illuminate me."[This message has been edited by Rei, 11-20-2003]

quote:

---

And what, pray tell, is astheticaly pleasing about THAT!

---

I have no clue - some people like it It just goes to show how dramatically things can mutate, though (in addition to how odd of tastes some people have!)So, are we all in agreement that mutations - both gradual and punctuated - can produce incredibly dramatic change in an organism even in the proportionally short period of time we're looking at here - or are these not dramatic enough yet? And, consequently, the only real question on your side as to whether there is some sort of barrier between levels of evolution is whether *good* changes (by natural selective factors) can occur, whether they can fixate into a population, and whether, if they can, they actually did?I should add that, to be able to have a pigeon handle mutations this dramatically - such as a giant chest or distorted spine - you're going to need to change the heart size, rearrange internal organs, and all sorts of chemical and structural rebalancing issues that will occur with the changes. Likewise, with the dogs, dogs have diverged this radically in historic times, and now have become a ring species, where the ends can no longer interbreed at all.------------------
"Illuminant light,
illuminate me."[This message has been edited by Rei, 11-20-2003]

quote:

---

That is an interesting assertion. I've seen it argued with. Do you have any references?

---

Not off hand, but the physical size difference alone will prevent it quite easily. Just to put it in perspective, a quick net search revealed a woman talking about the size of her great dane puppies - 650-850 grams. An adult chiuahua can weigh as little as 500 grams, although are typically 1500-2500 grams. The prospect of a chihuahua being able to mount a great dane (or vice versa) in nature is almost laughable. I am unaware of any attempts to cross breed a large dog with a small one through artificial insemination (since there is no way it could happen naturally), so I can't comment on whether it would be successful (clearly a chihuahua could not carry even a single great dane puppy, and it's doubtful they could carry an intermediate size; perhaps the other way around might work, however). Wolves and coyotes can breed successfully with dogs (wolfdogs and coydogs) of appropriate size, however. Dogs, were it not for the intermediates, would effectively have undergone cladogenic speciation to a higher degree than dogs as a whole have with wolves and coyotes. Given this - again, were it not for the intermediates still alive - their populations could only diverge further.I've seen some mention of dogs and foxes being able to occasionally crossbreed, but can't verify it.------------------
"Illuminant light,
illuminate me."

quote:

---

The pidgeons are still pidgeons and the dogs are still dogs. Not exactly the type of evidence required to show that all of life's diversity owes its collective common ancestry to some unknown population that just happened to have the ability to self-replicate. Methinks you don't know or understand what Creationists say about variation....

---

I'll ask again: Where Is The Barrier? What, Specifically, Are You Saying Is Impossible?Without a barrier, evolution is guaranteed, so you better have one.------------------
"Illuminant light,
illuminate me."

quote:

---

The fossil record cannot tell us of a mechanism nor can it tell us if genetic change was responsible. The only way the fossil record is evidence for the ToE is if you already believe in the ToE.

---

The first sentance is correct. However, the fossil record does need to be explained *somehow*. The ToE works far better than Lamarkism, and far, far better still than some sort of as-of-yet unexplained hydrologic flood sorting process (care to try your hand at it? Everyone's failed so far! If so, start a new thread; if not, please concede that you have no explanation for the universal and consistent fossil ordering that led early creationist scientists to have to abandon the theory). Furthermore, it matches up with all other methods that have been tested - multiple radioisotope testing, protein degradation, mineralization extent, influx of rare elements, etc. Finally, things are still evolving today. Thus, it is the theory that best fits the evidence.

quote:

---

Gradual changes are not found in the fossil record. Why is it that only fully formed alleged intermediates are found?

---

There are many cases where even the intermediates between the stable plateus are quite present, such as whales, horses, some primates, sharks (at least concerning teeth and scales, which preserve quite well), many bivalves and crustaceans, etc - basically, things that both (A) preserve well, and (B) were living in areas where deposition was occurring, as opposed to erosion. Naturally, of course, species tend toward equilibrium positions, and remain there until equilibrium is disrupted. It occurs today, so why wouldn't it occur in the past?

quote:

---

Where are all of nature's failed experiments?

---

Most lineages *did* die out. That's the reason you don't, say, see any dinosaurs around today.------------------
"Illuminant light,
illuminate me."[This message has been edited by Rei, 12-17-2003]

quote:

---

Fossilization requires a quick burial- that goes against gradualism.

---

To quote Jon Stewart: "Whaaaaaaaaa?"Please explain.

quote:

---

It also shoots down how we date the GC.

---

Again, explanation needed. Keep in mind that "quick burial" means a few to a few hundred years (depending on the environment), not "3 seconds". It just has to occur before the fossil bones get eroded/decomposed to pieces and turn into bone dust.

quote:

---

The only reason to believe a dinos forelimbs evolved into wings is faith. There isn't any evidence to support that claim- but if you can show me to be wrong I will look into it.

---

You mean, there aren't intermediates to forelimbs as wings? Such as, oh let's just say, flying squirrels which use their forelimbs to glide while leaping? Please present your barrier.The fossil record also backs us up here, with fossils such as archaeopteryx (among others).P.S. - have you ever looked at a bat's skeleton? Try and claim that these aren't just elongated arms and fingers:------------------
"Illuminant light,
illuminate me."[This message has been edited by Rei, 12-17-2003]

quote:

---

It's funny that you bring up bats because there isn't any fossil evidence for their alleged evolution.

---

Ever heard of Icarnycteris (thanks for the pic, lpetrich!)

quote:

---

If bat's wings were just elongated arms/ fingers then it would be a given that the genes that govern the limbs/ fingers were what mutated. What happens if embryology falsifies that notion?

---

Here's their physical structureHey, Mammuthus, do you have a link on the genetics for this one? I got the morphology taken care of!

quote:

---

BTW, homolgy has been falsified for years.

---

You've said this at least four times now, and not backed it up once. I don't appreciate that sort of thing. Back it up now, or quit saying it.

quote:

---

Look up fossilization. If an organism isn't buried within 2 years tops it will not fossilize, it will deteriorate. Trace fossils left on the surface will erode.

---

I'm growing tired of your incorrect assertions. The type of fossilization being discussed here is called permineralization (for more about fossilization, read). Perimineralization can occur on fossils that have been exposed for more than 100 years. Now, please, quit asserting on subjects that you know nothing about.

quote:

---

Flying squirrels glide, they don't fly. A variation of a regular squirrel. No big deal.

---

I'll ask again: Where's the barrier? How many times do I have to ask this? You're asserting that there's a barrier; every time that I ask what it is, you ignore my question. Don't ignore it this time: what supposedly will prevent gradualism from continuing? Without a barrier, and with continual selective pressure, gradualism is guaranteed to continue, so you better have one if you want your position to be tenable.------------------
"Illuminant light,
illuminate me."

quote:

---

crashfrog, We Have NEVER observed mutations accumulating in the way the theory of evolution requires. Genetic homeostasis- the observed limit. Also we know that even the most beneficial mutation has a greater chance of being lost in a population than it does of becoming fixed, never mind taking over that population.

---

False, as I physically demonstrate over here.------------------
"Illuminant light,
illuminate me."

--------------------------- http://www.ncbi.nlm.nih.gov:80/...Organization of forelimb motoneuron pools in two bat species (Eptesicus fuscus and Myotis lucifugus).Ryan JM, Cushman J, Baier C.Biology Department, Hobart and William Smith Colleges, Geneva, N.Y. 14456, USA. ryan@hws.eduThe present investigation provides further evidence of the conservation of motor nuclei in amniotes. The position of six forelimb and shoulder motor pools were mapped in two species of bat, Eptesicus fuscus and Myotis lucifugus. The intraspinal locations of motor pools were revealed by labeling with the retrograde neuronal tracer WGA-HRP injected into the bellies of six muscles: m. pectoralis, m. spinodeltoideus, mm. triceps brachii (long and lateral heads), m. infraspinatus, m. supraspinatus, and m. biceps brachii. The positions of the labeled motor pools were reconstructed from serial transverse and horizontal sections of the spinal cord. WGA-HRP-labeled cells were located midway between cervical spinal nerves four and five to midway between cervical spinal nerve eight and the first thoracic spinal nerve. Individual motor pools formed fusiform clusters of cells with little intermingling of neurons between adjacent motor pools. The pectoralis motor pool contained significantly more motoneurons than all other motor pools for M. lucifugus. The pectoralis pool in E. fuscus contained more motoneurons than the biceps, supraspinatus, and infraspinatus, but not the spinodeltoid or the triceps brachii. The biceps, spinodeltoid, infraspinatus and supraspinatus pools were located rostrally; the pectoralis and triceps pools caudally. The pectoralis pool was the most medial and the spinodeltoid pool was the most lateral. These data suggest that the locations of shoulder and forelimb motor pools are ontogenetically and phylogenetically conserved across tetrapods and independent of the function of the muscles in adults---------------------------(i.e., bats use the same neuron pools in their wings as we use in our arms)---------------------------
http://www.ncbi.nlm.nih.gov:80/...
Full article: NCBIWe present 744 nucleotide base positions from the mitochondrial 12S rRNA gene and 236 base positions from the mitochondrial cytochrome oxidase subunit I gene for a microbat, Brachyphylla cavernarum, and a megabat, Pteropus capestratus, in phylogenetic analyses with homologous DNA sequences from Homo sapiens, Mus musculus (house mouse), and Gallus gallus (chicken). We use information on evolutionary rate differences for different types of sequence change to establish phylogenetic character weights, and we consider alternative rRNA alignment strategies in finding that this mtDNA data set clearly supports bat monophyly. This result is found despite variations in outgroup used, gap coding scheme, and order of input for DNA sequences in multiple alignment bouts. These findings are congruent with morphological characters including details of wing structure as well as cladistic analyses of amino acid sequences for three globin genes and indicate that neurological similarities between megabats and primates are due to either retention of primitive characters or to convergent evolution rather than to inheritance from a common ancestor. This finding also indicates a single origin for flight among mammals.---------------------------(Summary: bats are not only genetically close to other mammals, but morphological changes match where they would be expected to be in their genome for a bat to have evolved from a mammal, and not where they would be in a bird's genome)---------------------------So, in short, once again, given your statement:

quote:

---

If bat's wings were just elongated arms/ fingers then it would be a given that the genes that govern the limbs/ fingers were what mutated. What happens if embryology falsifies that notion?

---

Once again, for the millionth time, evolution makes a correct prediction, and creationism an incorrect one.P.S. - As you may notice, we're all getting sick of your "There must be an ocean between New York and San Francisco, but I'm not going to tell you where I think it is, it's your job to find my proported ocean despite no evidence for its existance."------------------
"Illuminant light,
illuminate me."{Shortened display form of 2 URLs, to restore page width to normal - Adminnemooseus}This message has been edited by Adminnemooseus, 09-15-2004 12:49 PM

In addition to what Mr.Hombre said, you're moving the goal posts. You start off asking if we even know whether the same genes correspond (as if you expected them not to correspond). Evolution says they will. There's no reason they have to at all - (after all, why would God design the world to look like common lineages *every last time* instead of mixing and matching features?) - but, whatdya know, they do! (*every last time*). Now you're basically saying "of course they match up".They're not just the same genes, either - they show alterations to the DNA that mimics the exact way that we see DNA currently changing - frame shift mutations in addition to random substitutions, etc.------------------
"Illuminant light,
illuminate me."[This message has been edited by Rei, 12-19-2003]

quote:

---

Creationists don't know what the original kind is. Only that it can't be too off the mark of the present kinds.

---

So, to sum up, you're debating using "Argument from personal incredulity." Great. Do you have anything, then, to back up the notion that there is some sort of distinction between "kinds" which cannot be bridged by natural selection?I should start classifying my Framsticks-evolved creatures into "kinds". In my current sim, I've had "Diatoms", "Sinkers", "Bouncers", "Clappers", "Hoppers", and "Fumblers". They all look and behave quite differently. This message has been edited by Rei, 09-21-2004 03:09 PM

---

"Illuminant light,
illuminate me."

quote:

---

Any separation of kind theefore we put under the label micro and it fits fine with observation and evidence.

---

So, in short, you define your limits on what can evolve based on a term you can't define.Care to get a little more specific, or should we reduce our arguments to one person shouting "Yes!" and the other "No!"?

---

"Illuminant light,
illuminate me."