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Forums - General - An evolution question I've often wondered about.

Kasz216 on 23 November 2009
stof said:
Vagabond(well thought out stuff by the way) - But if breeding between certain brands can only be achieved through scientific procedures, then from an evolutionary standpoint (the ability to reproduce), wouldn't we consider that a speciation event?

Ironman - And a lion and a tabby are both cats, but they're different species.

Khuutra - right, But those offspring can't reproduce. The definition of a seperate species is that they they can produce offspring that can reproduce. A Liger and a Mule can't have kids. If they could, tigers and lions would be the same species, as would donkey's and horses.


Montana - I'm sure there are videos for sale of 8 foot tall men and 3 foot tall women doing their damndest to prove you wrong Montana. But I'm not just talking size, though it is the most easy to illustrate with pictures. What I'm trying to say is that as far as I'm aware, there are some breeds of dogs that just can't produce offspring together (outside of a laboratory). Now I'm not sure if all breeds of dogs can eventually mingle through intermediary dog breeds. But even if that's the case, then wouldn't the only thing stopping a speciation event (I like that word Vagabond) be for one or more of those intermediary breeds to die out?

No.  Because they are still genetically compatable.  It's when they aren't gentically compatable that counts.

Of course the truth is that there is not a lot of real science in what defines a species.  They started defining species before they even knew what a species was... so it's all insane.


There is no accurate or widely accepted term for species... as ridiculious as that may sound.


The genetically compatable model just makes more sense, because if you use the biological model, that means if i take a family of dogs of say, Golden retrievers, and suddenly let them in the wild and watch them breed with wolves... then Golden retrivers are suddenly wolves under this model.

This is... ridiculious.

 

However the genetic model has yet to win out because of people generally being stubborn.  Scientists included.  Nobody wants their dog to suddenly be a wolf.


Despite the genetic differentces between gray wolves and dogs being around .2% and some genetic studies actually would put wolves as a "species" of dog right in the middle of the genetic differences.



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Kasz216 on 23 November 2009

There is also Typological speciation... but that has just as much problems as the above.

Though Typological speciation is probably what you'd like most stof if you'd like to believe different dog breeds are there one species.

I still maintain that genetic capability is the only unbiased and logical way to look at it however.



Reasonable on 23 November 2009

It's called selective evolution (sometimes I think artificial). Basically, we've selected for the dogs who gets to breed, removing the environment, etc. almost completely from the picture. One of the interesting elements of selective breeding is that you can change species pretty quickly vs say natural evolution where changes take a long time to happen.

Of course, if we were to also bring genetic manipulation into the equation alongside selective evolution, I guess we could change species ever faster.



Try to be reasonable... its easier than you think...

NJ5 on 23 November 2009

Kasz216 aren't dogs a subspecies and not a species?

According to wikipedia they are:

Species - Canis Lupus (like the wolf)
Subspecies - Canis Familiaris



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ironman on 23 November 2009
stof said:
Vagabond(well thought out stuff by the way) - But if breeding between certain brands can only be achieved through scientific procedures, then from an evolutionary standpoint (the ability to reproduce), wouldn't we consider that a speciation event?

Ironman - And a lion and a tabby are both cats, but they're different species.

Khuutra - right, But those offspring can't reproduce. The definition of a seperate species is that they they can produce offspring that can reproduce. A Liger and a Mule can't have kids. If they could, tigers and lions would be the same species, as would donkey's and horses.


Montana - I'm sure there are videos for sale of 8 foot tall men and 3 foot tall women doing their damndest to prove you wrong Montana. But I'm not just talking size, though it is the most easy to illustrate with pictures. What I'm trying to say is that as far as I'm aware, there are some breeds of dogs that just can't produce offspring together (outside of a laboratory). Now I'm not sure if all breeds of dogs can eventually mingle through intermediary dog breeds. But even if that's the case, then wouldn't the only thing stopping a speciation event (I like that word Vagabond) be for one or more of those intermediary breeds to die out?

Yes, but both species stem from the same family, no matter what you do, they will still be a cat.



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Khuutra on 23 November 2009

Hey guys it turns out that only male Tiglons are sterile all the time: the females actually aren't, and can mate with lions and tigers and so forth.

I don't really know how that affects the discussion, but doesn't that make lions and tigers genetically compatible?



sc94597 on 23 November 2009
Khuutra said:
Hey guys it turns out that only male Tiglons are sterile all the time: the females actually aren't, and can mate with lions and tigers and so forth.

I don't really know how that affects the discussion, but doesn't that make lions and tigers genetically compatible?

That is wierd. Can you link me, or tell me where you read/heard that? Maybe it has something to do with mtDNA and Y-DNA. Y-DNA being is transfered Paternally, and mtDNA is tranferred Maternally. I'm thinking maybe a closer Maternal ancestor? Also, how does the species they mix with affect it? Are they more compatible with a Lion or a Tiger?



Khuutra on 23 November 2009
sc94597 said:
Khuutra said:
Hey guys it turns out that only male Tiglons are sterile all the time: the females actually aren't, and can mate with lions and tigers and so forth.

I don't really know how that affects the discussion, but doesn't that make lions and tigers genetically compatible?

That is wierd. Can you link me, or tell me where you read/heard that? Maybe it has something to do with mtDNA and Y-DNA. Y-DNA being is transfered Paternally, and mtDNA is tranferred Maternally. I'm thinking maybe a closer Maternal ancestor?

http://en.wikipedia.org/wiki/Liger#Fertility

Apparently taken from Wild Cats of the World (1975) by C. A. W. Guggisberg.



Khuutra on 23 November 2009
sc94597 said:

I'm thinking maybe a closer Maternal ancestor? Also, how does the species they mix with affect it? Are they more compatible with a Lion or a Tiger?

From the Wikipedia page on "Tiglon":

At the Alipore Zoo in India, a female tiglon named Rudhrani, born in 1971, was successfully mated to an Asiatic Lion named Debabrata. The rare, second generation hybrid was called a litigon (pronounced /ˈlaɪˌtaɪ.ɡən/). Rudhrani produced seven litigons in her lifetime. Some of these reached impressive sizes—a litigon named Cubanacan (died 1991) weighed at least 363 kilograms (800 lb), stood 1.32 metres (4.3 ft) at the shoulder, and was 3.5 metres (11 ft) in total length.

Reports also exist of the similar titigon (/ˈtaɪˌtaɪ.ɡən/), resulting from the cross between a female tiglon and a male tiger. Titigons resemble golden tigers but with less contrast in their markings. A female tiglon born in 1978, named Noelle, shared an enclosure in the Shambala Reserve with a male Siberian Tiger called Anton, due to the keepers' belief that she was sterile. In 1983 Noelle produced a titigon named Nathaniel. As Nathaniel was three-quarters tiger, he had darker stripes than Noelle and vocalized more like a tiger, rather than with the mix of sounds used by his mother. Being only about quarter-lion, Nathaniel did not grow a mane. Nathaniel died of cancer at the age of eight or nine years. Noelle also developed cancer and died soon after.



Kasz216 on 23 November 2009
NJ5 said:
Kasz216 aren't dogs a subspecies and not a species?

According to wikipedia they are:

Species - Canis Lupus (like the wolf)
Subspecies - Canis Familiaris

They shouldn't be though.  As some dogs are more genetically related to wolves then other dogs.