What is the minimum difference required for two animals to be unable to breed?

[oaty]

I have a very basic understanding of evolution, and find it fascinating but still have gaps/questions.

 

When for example a certain species population is split geographically, and given enough time they slowly begin to differ, due to demands of environment etc there must come a point when they are no longer able to breed with the other group they were split from.

 

But something tells me that the 'cut off line' could not be that neat, as everything else in this process is so gradual and I could not imagine one animal being able to breed with the other group, but who's offspring couldnt

 

 

 

I would be grateful for anyone wiser on the subject to shed some light!

 

 

[dragonstar57]

as soon as the # of chromosomes are different

[oaty]

as soon as the # of chromosomes are different

 

 

 

 

Ok, but could that happen in a single generation? And does that mean people with conditions that affect their chromosomes cannot breed?!

[Ophiolite]

It is a continuum. Lions and tigers can interbreed, but they are very clearly separate species. In the wild they have no opportunity to do so. Some fish species (details forgotten, but I'll try to find them if you need me to) living in the same area, but with different behaviours choose not to interbreed even though they are genetically compatabile. There is no absolute cut off, though chickens rarely make it with elephants.

[skyhook]

I have a very basic understanding of evolution, and find it fascinating but still have gaps/questions.

 

When for example a certain species population is split geographically, and given enough time they slowly begin to differ, due to demands of environment etc there must come a point when they are no longer able to breed with the other group they were split from.

 

But something tells me that the 'cut off line' could not be that neat, as everything else in this process is so gradual and I could not imagine one animal being able to breed with the other group, but who's offspring couldnt

 

 

 

I would be grateful for anyone wiser on the subject to shed some light!

 

 

 

I find this wikipedia entry about coyote hybrids quite interesting... http://en.wikipedia....ki/Canid_hybrid

 

I think it is a relatively gradual process. everything is constantly evolving, but the rates are not the same for each species. so the accumulated difference over thousands of generations may have make two species too far apart to be compatible.

 

I've heard the coyote can eat a small dog. and the wolf will kill a coyote. There is a difference in inherent behaviors that they rarely produce hybrids. They are still capable of cross breeding, The cutoff is not very clear.

Edited November 6, 2010 by skyhook

[CharonY]

It can be large differences, but it could also be small ones. E.g. when a certain allele combination is for whatever reason lethal.

However, more the the point, you should look up speciation (especially allopatric speciation). Together with certain stochastic events and a certain base gene pool, speciation events can sometimes be relatively rapid.

Edited November 6, 2010 by CharonY