|
Register | Sign In |
|
QuickSearch
Thread ▼ Details |
|
Thread Info
|
|
|
Author | Topic: Pigeons and Dogs: Micro or Macro evolution? | |||||||||||||||||||||||||||||
Rei Member (Idle past 7012 days) Posts: 1546 From: Iowa City, IA Joined: |
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."
|
|||||||||||||||||||||||||||||
keith63 Inactive Member |
Anyway to do an open forum so the topics can lead where they may? It seems everytime a topic gets interesting someone is always reminding you of the original thread.
|
|||||||||||||||||||||||||||||
Rei Member (Idle past 7012 days) Posts: 1546 From: Iowa City, IA Joined: |
Feel free to stray - I'll hold the admins off for you to the best of my ability hehe
------------------"Illuminant light, illuminate me."
|
|||||||||||||||||||||||||||||
AdminAsgara Administrator (Idle past 2302 days) Posts: 2073 From: The Universe Joined: |
< glares menacingly in the general direction of Rei >
------------------
AdminAsgara Queen of the Universe
|
|||||||||||||||||||||||||||||
Rei Member (Idle past 7012 days) Posts: 1546 From: Iowa City, IA Joined: |
( drat! They found us! )
------------------"Illuminant light, illuminate me."
|
|||||||||||||||||||||||||||||
TheoMorphic Inactive Member |
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?
yeah that's it.
|
|||||||||||||||||||||||||||||
Dr Jack Member Posts: 3514 From: Immigrant in the land of Deutsch Joined: Member Rating: 8.7 |
Anyway to do an open forum so the topics can lead where they may? It seems everytime a topic gets interesting someone is always reminding you of the original thread. The trouble with that approach is that it leads to muddy threads, in which interesting thoughts or ideas get lost. If you want to discuss an aside which interests you, just create a new thread and pop in a link to it.
|
|||||||||||||||||||||||||||||
Rei Member (Idle past 7012 days) Posts: 1546 From: Iowa City, IA Joined: |
quote: 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]
|
|||||||||||||||||||||||||||||
Yaro Member (Idle past 6495 days) Posts: 1797 Joined: |
Rei! Your scaring the piss outta me!
OMFG!!! These pigeons are gonna give me nightmares! It's like some sort of Max Ernst hallucination!
And what, pray tell, is astheticaly pleasing about THAT!
|
|||||||||||||||||||||||||||||
Rei Member (Idle past 7012 days) Posts: 1546 From: Iowa City, IA Joined: |
quote: 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]
|
|||||||||||||||||||||||||||||
NosyNed Member Posts: 8996 From: Canada Joined: |
"ends can not longer interbreed at all"
That is an interesting assertion. I've seen it argued with. Do you have any references?
|
|||||||||||||||||||||||||||||
TheoMorphic Inactive Member |
This forum is going to be the death of me (or at least the reason i fail a class... well it's just guitar... not like my academic future rests on this class... anyway)...
so is it theoretically possible to link every species to every other species through interbreeding? like you say there are ring species make a sort of chain that connects various animals... but is it possible to extend that chain to encompass every animal on the planet? where would the lines be drawn on a chain like that?
|
|||||||||||||||||||||||||||||
Rei Member (Idle past 7012 days) Posts: 1546 From: Iowa City, IA Joined: |
quote: 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."
|
|||||||||||||||||||||||||||||
Chiroptera Inactive Member |
quote:Sure, if we're allowed to go back into time and link species through common ancestors. This is the standard (from here) that links all life together. But if you insist on sticking with present species, then, no, there is no other species that humans can interbreed with, for example.
|
|||||||||||||||||||||||||||||
NosyNed Member Posts: 8996 From: Canada Joined: |
there is no other species that humans can interbreed with Absence of evidence? There is no way someone would be nuts enough to try this experiment but I wonder.
|
|
|
Do Nothing Button
Copyright 2001-2023 by EvC Forum, All Rights Reserved
Version 4.2
Innovative software from Qwixotic © 2024