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Question about species

leet4A1
Posts: 1,986
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9/6/2009 7:32:40 PM
Posted: 7 years ago
First of all, yes I believe in evolution (macro and micro), I believe humans and apes are from a common ancentor, etc. I find the theory beautiful in its explanitory power, and from the little I know about biology, I can't fault it at all.

But, I've got a question for those out there who know more about it than I (particularly Kleptin):

How does speciation occur? What are the steps? I know (or at least think I know) that what distinguishes one species from another is that members of different species can't interbreed with eachotehr. So when speciation occurs, does it just so happen that an individual or entire generation are born to an individual, who can no longer reproduce with members of the species they formerly belonged to? If so, wouldn't that mean that the only way a new species could start would be through incest?

This is probably a really, really dumb question, and I'm hoping someone can give me a good answer because I've been wondering about it for a while now.
"Let me tell you the truth. The truth is, 'what is'. And 'what should be' is a fantasy, a terrible terrible lie that someone gave to the people long ago. The 'what should be' never did exist, but people keep trying to live up to it. There is no 'what should be,' there is only what is." - Lenny Bruce

"Satan goes to church, did you know that?" - Godsands

"And Genisis 1 does match modern science... you just have to try really hard." - GR33K FR33K5
sherlockmethod
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9/6/2009 7:40:10 PM
Posted: 7 years ago
Your question is not stupid. The answer is a bit long so I will put something together and give you some book recommendations. Interbreeding is important, but species can be different even if they are capable of interbreeding in a lab. Give me some time and I will give you a good answer and some material to study further.
Library cards: Stopping stupid one book at a time.
leet4A1
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9/6/2009 7:43:41 PM
Posted: 7 years ago
At 9/6/2009 7:40:10 PM, sherlockmethod wrote:
Your question is not stupid. The answer is a bit long so I will put something together and give you some book recommendations. Interbreeding is important, but species can be different even if they are capable of interbreeding in a lab. Give me some time and I will give you a good answer and some material to study further.

Thanks brother! I'm currently reading Dawkins' The Ancestor's Tale, so it may be mentioned in there but I haven't come to it yet.
"Let me tell you the truth. The truth is, 'what is'. And 'what should be' is a fantasy, a terrible terrible lie that someone gave to the people long ago. The 'what should be' never did exist, but people keep trying to live up to it. There is no 'what should be,' there is only what is." - Lenny Bruce

"Satan goes to church, did you know that?" - Godsands

"And Genisis 1 does match modern science... you just have to try really hard." - GR33K FR33K5
Volkov
Posts: 9,765
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9/6/2009 7:47:29 PM
Posted: 7 years ago
While I can guarantee Kleptin will have a better answer, I'll see if I can explain it.

Speciation doesn't occur overnight. It takes awhile, and it goes through many generations. So it isn't as if a child is born that automatically cannot mate with other members of the species; it is a gradual process, and by the time the creatures are sufficiently different enough from their ancestor species, the entire population will be the same. This is because it is the much older generations that the new species cannot mate with; not the immediate generations, which share enough DNA that mating is possible.

Now, that tackles the question of incest as well; since the entire population is on the same footing, there is no need for incest to occur.

As far as I know, no speciation occurs with a single individual creature; it is the entire population which adapts and evolve, because the entire population is being affected by climactic changes or whatever. An individual creature that gets stuck in another climate cannot pass on any adaptations - even a single family cannot do that, due to the fact that there will be incest and the shared DNA will just screw everything up.

"Populations," by the way, refer to the population within a given but distinct region; some populations of the same species do live in different regions. What occurs in one region will probably not be the same as what occurs in another, so when one region has, say, less vegetation, the population in that region will evolve differently from the population in the region with more vegetation. The end result is two different species that evolved based on their situations, but they cannot mate due to that different evolutionary pattern - even though they had the common ancestor.

I hope this helps a little. Ask questions if you'd like.
sherlockmethod
Posts: 317
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9/6/2009 7:50:26 PM
Posted: 7 years ago
At 9/6/2009 7:41:46 PM, wjmelements wrote:
How do we define a species?

Another great question. Shanedk does a good job showing the difficulty in this matter.
Library cards: Stopping stupid one book at a time.
leet4A1
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9/6/2009 7:54:49 PM
Posted: 7 years ago
At 9/6/2009 7:47:29 PM, Volkov wrote:
While I can guarantee Kleptin will have a better answer, I'll see if I can explain it.

Speciation doesn't occur overnight. It takes awhile, and it goes through many generations. So it isn't as if a child is born that automatically cannot mate with other members of the species; it is a gradual process, and by the time the creatures are sufficiently different enough from their ancestor species, the entire population will be the same. This is because it is the much older generations that the new species cannot mate with; not the immediate generations, which share enough DNA that mating is possible.

Now, that tackles the question of incest as well; since the entire population is on the same footing, there is no need for incest to occur.

As far as I know, no speciation occurs with a single individual creature; it is the entire population which adapts and evolve, because the entire population is being affected by climactic changes or whatever. An individual creature that gets stuck in another climate cannot pass on any adaptations - even a single family cannot do that, due to the fact that there will be incest and the shared DNA will just screw everything up.

"Populations," by the way, refer to the population within a given but distinct region; some populations of the same species do live in different regions. What occurs in one region will probably not be the same as what occurs in another, so when one region has, say, less vegetation, the population in that region will evolve differently from the population in the region with more vegetation. The end result is two different species that evolved based on their situations, but they cannot mate due to that different evolutionary pattern - even though they had the common ancestor.

I hope this helps a little. Ask questions if you'd like.

Now that makes a lot more sense than the view I had, which was that speciation occurs in one generation. Thanks very much Volkov.
"Let me tell you the truth. The truth is, 'what is'. And 'what should be' is a fantasy, a terrible terrible lie that someone gave to the people long ago. The 'what should be' never did exist, but people keep trying to live up to it. There is no 'what should be,' there is only what is." - Lenny Bruce

"Satan goes to church, did you know that?" - Godsands

"And Genisis 1 does match modern science... you just have to try really hard." - GR33K FR33K5
regebro
Posts: 1,152
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9/7/2009 12:06:03 AM
Posted: 7 years ago
At 9/6/2009 7:32:40 PM, leet4A1 wrote:
How does speciation occur? What are the steps? I know (or at least think I know) that what distinguishes one species from another is that members of different species can't interbreed with eachotehr. So when speciation occurs, does it just so happen that an individual or entire generation are born to an individual, who can no longer reproduce with members of the species they formerly belonged to? If so, wouldn't that mean that the only way a new species could start would be through incest?

It can't happen to one individual, as that individual would not be able to get kids with anyone else. And I can't happen to one individuals children either. I think that both should be genetically impossible, andin that case these children would only be able to interbreed with each other, and that's to few to create a viable population. It wouldn't be interbred, it would be inbred. :-)

So it's a slow process, yes. It typically happens when one group gets isolated from the rest of the species for a longer time, often by purely geographical means.
So prove me wrong, then.
Kleptin
Posts: 5,095
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9/7/2009 8:11:04 AM
Posted: 7 years ago
At 9/6/2009 7:32:40 PM, leet4A1 wrote:
First of all, yes I believe in evolution (macro and micro), I believe humans and apes are from a common ancentor, etc. I find the theory beautiful in its explanitory power, and from the little I know about biology, I can't fault it at all.

But, I've got a question for those out there who know more about it than I (particularly Kleptin):

How does speciation occur? What are the steps? I know (or at least think I know) that what distinguishes one species from another is that members of different species can't interbreed with eachotehr. So when speciation occurs, does it just so happen that an individual or entire generation are born to an individual, who can no longer reproduce with members of the species they formerly belonged to? If so, wouldn't that mean that the only way a new species could start would be through incest?

This is probably a really, really dumb question, and I'm hoping someone can give me a good answer because I've been wondering about it for a while now.

This is a question that I've struggled with for quite a while myself, and as of now, I regret so say that I *still* don't have that good of an answer for it. This question is something that I'd look to sherlock for, as he has a much better grasp than I. I'll give you whatever little I have floating in my head so far though.

As Volkov mentioned, geographic isolation is probably the best example of speciation. In this manner, the gene pool isn't split between an entire species and one member with a mutation, but a split in the species overall. Each portion is large enough to continue reproducing within the niche and adapting over time, but diverge such that their genetic differences build up to such an extent that they are unable to cross-breed.

Another concept I have been toying around with is the notion that species can develop as a mechanism against depletion of resources. I recall reading somewhere that there is a specific term for this, but I'm too lazy to internet around and find it. It's akin to the principle of economics and specialized labor.

If a whole bunch of Chinese restaurants open up, business will be limited. One of them decides to do both Chinese and Japanese food, and a few others follow suit. The niche has opened and there is more business for everyone. Eventually, one of them will decide to specialize in Japanese food and when some others follow suit, the fusion restaurants will die out since there is specialized Chinese food and specialized Japanese food in the same area.

Darwin's finches are another example. Although there really was no genetic isolation, the finches occupied different niches so that they can take advantage of different food sources instead of end up competing and limiting their population. Assuming that a slight mutations allowed an original seed-eating population to begin eating nuts as a back-up, this dual-purpose beak was selected for. Since the already-established seed eating population has severely restricted the amount of seeds, nut-eating beaks will be selected for until it evens out. Hybrid beaks will then be less efficient than either seed-eating or nut-eating and the hybrids will die out in favor of specialized niches.
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tkubok
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9/7/2009 9:52:10 AM
Posted: 7 years ago
Just to comment a bit...

At 9/7/2009 8:11:04 AM, Kleptin wrote:
Another concept I have been toying around with is the notion that species can develop as a mechanism against depletion of resources. I recall reading somewhere that there is a specific term for this, but I'm too lazy to internet around and find it. It's akin to the principle of economics and specialized labor.
Bottleneck effect. Thats what it is called, i believe.

Darwin's finches are another example. Although there really was no genetic isolation, the finches occupied different niches so that they can take advantage of different food sources instead of end up competing and limiting their population. Assuming that a slight mutations allowed an original seed-eating population to begin eating nuts as a back-up, this dual-purpose beak was selected for. Since the already-established seed eating population has severely restricted the amount of seeds, nut-eating beaks will be selected for until it evens out. Hybrid beaks will then be less efficient than either seed-eating or nut-eating and the hybrids will die out in favor of specialized niches.
Actually, i believe Darwins Finches were of Allopatric speciation, that is, the finches were geographically isolated within each different island, as well as other geographic barriers. If i remember correctly, i believe the Turtles were the ones who underwent the bottleneck effect, due to the fact that the food source was out of reach and only the turtles who could reach it were able to survive.
sherlockmethod
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9/7/2009 5:06:40 PM
Posted: 7 years ago
Before I answer some speciation questions, I will clear up this micro/macro idea. Macro evolution is not a "bigger" change than micro. Macro is simply a term used to describe changes including the speciation event and beyond. Micro will also apply to speciation so the difference between the two is small. Macro is the study of the speciation and extinction rates of populations using the effects of genetic drift and other evolutionary processes as points of study; one will find work dealing with punctuated equilibrium, gene duplication, and studying the parent population in comparison to the present population. Micro deals mainly with changes in alleles within a species. The speciation event that gave rise to reptiles and birds is as much micro/macro as the speciation event giving rise to nylon eating bacteria.

The best analogy comes from economics. Micro economics deals with money and exchanges at a local level. This level could be a county, a state, a province, or even a country in some respects. Macro deals with such matters as tariffs, the Federal Reserve, exchange rates with currency, etc. Both have the same binding concept – money. The micro/macro changes affect each other and cannot be completely isolated from one another; the theory of evolution is no different. Do not let creationists confuse you with these terms.

What is a species?
I linked a video in this thread from shanedk, I recommend everyone watch as it is very well done. Volkov and Kleptin gave great answers on speciation also. In the simplest form, a species is an isolated gene pool. Creatures that can mate in nature and produce fertile offspring are generally considered the same species. The problem arises when dealing with asexual organisms as they do not require a mate. Because species are not fixed the term is fluid and the computer science principle, "fuzzy logic", will serve us well when addressing species (see video). We are going to go back in time now and start with one of the greatest scientists in history and talk about species.

Carolus Linnaeus: "I will sort and name many things" (Blueprints: Solving the mystery of evolution, Edey & Johanson)
Scientists were labeling specimens using independent methods and no one could make heads or tails of the situation. The natural sciences needed a classification system. Linnaeus gave us one. He gave two names to every organism, the first was the genus, the second the species. "A genus is a group…of similar creatures that obviously are very closely related, but contains within the group individual types that are consistently different from one another. Those different types are species." (at 11) This book uses the worm as an example, stating clearly and accurately, the fact that the difference between some worms is as great as the difference between a chicken and a rhinoceros. Now, this is not cut and dry and I will use a favorite example from creation science to illustrate my point: the domestic dog.

EXAMPLE:
A Teacup Chihuahua is part of the Canis familiaris (genus) (species)
A Great Dane is part of the Canis familiaris.

Why are these two in the same species? They cannot breed naturally due to size (this is debatable, but I can find no example of such an experiment). Shouldn't they be different species? (Sorry for the visual there) The answer is no because the Teacup and the Great Dane have a gene flow within the whole population. They may not be able to produce with each other, but each can produce with a different breed (variants) and in a few generations the offspring will not have the size barrier. Because the gene flow does not stop, these two are in the same species, but do not mate with each other … Woofles, get back in here, leave that Great Dane alone. What are you? Oh my … how is that? … Where did you get that ladder? Please stop. I can never unsee that. <Sherlock gets a drink, back in a few hours> I will keep DDO updated on Woofles; bad dog.

Now let's experiment here. What happens when we remove all the breeds except the teacup and the Great Dane? For whatever reason, all dog breeds start to die off but the teacup, due to size, location, whatever, makes it. The Great Dane does the same. Both are still dogs, but they cannot interbreed and the necessary biological bridge (other variants) is gone. We would now have two separate species. They would share a biological past, but each will have separate evolutionary futures. We would no longer refer to them as Canis Familiaris as all the traits found in that species are not found in the two new ones! This is an example of one type of speciation. Please note, the animals did nothing different. The alleles changed just as they do today but these two variants (teacup and Great Dane) were selected and the gene flow between them stopped with the removal of other variants. The changing of alleles within the population (micro) gave rise to many variants, some that could not reproduce with each other, when the gene flow stopped and new species emerge they will go separate ways in nature (macro).

Well Sherlock wouldn't species be arbitrary then?

No, they are not arbitrary. Nature acts on isolated gene pools and once those gene pools split nature will act to each differently. The Great Dane must now mate with wolves or other Danes and lose all the other aspects attributed to dogs. The Tea Cup must find a new niche due to its size and the available food sources. Nature will not treat each the same; they are different species.

Hey, you cheated. This is not speciation; the dog is still a dog and not a cat or a bird.
Correct, dogs do not turn into birds or cats but this is speciation. No magic needed.

END OF PART I
I hope this helps some.
Library cards: Stopping stupid one book at a time.