Interspecies breeding

[IngoVals]

If I remember correctly one definition of Species is that if it can mate and have a fertile offspring it's the same species. The fertile part is because some species can breed which almost always results in a sterile offspring.

 

What is it the makes a species able to breed with another? Do the still share so many common genes involving breeding while others have changed more? Is there something specific Gene-wise that controls when they can.

 

Why do the offspring become sterile?

 

What are some species that can breed. I remember Mule and Liger and some where the species are more similiar then most breeds of dogs ( wolfs/coyotes, polar bear/grizzly) What are the more stranger ones?

 

Also why can dog breeds look so different and still be the same species while things like gray/ red wolf, black/brown bear, white/black rhino look almost identical but are seperate species?

 

Donkey's and Horses ( and zebras ) are quit different looking, so is the Lion and the Tiger. Many species are closer in appearance so I would think more likely to interbreed. Has anyone thought about the possibility of a human/chimp or human/gorilla possibilities ( I'm just talking wether genetics would allow it, not suggesting anything and certainly not volunteering ).

[Mr Skeptic]

Species is more or less an arbitrary distinction, except the particular definition you gave involving reproduction. However, then you can make a new species with exactly the same genes by changing the number of chromosomes or somesuch.

[DJBruce]

What is it the makes a species able to breed with another?

 

There are 5 prezygotic barriers, and 3 postzygotic barriers which make it impossible for pieces to breed. They prezygotic barriers are:

 

- Temporal Isolation: The two pieces are reproductively active at different times.

- Habitat Isolation: The two species live in different areas, and therefore do not meet to mate.

- Behavioral Isolation: The two species have different mating rituals/

- Mechanical Isolation: The two species reproduction parts just don't fit together properly.

- Gametic Isolation: The two species gametes are incompatible making fertilization impossible.

 

The three postzygotic barriers are:

 

- Hybrid Inviablity: The hybrid does not mature properly into a function offspring.

- Hybrid Sterility: The hybrid is sterile normally because of gametic abnormalities.

- Hybrid Breakdown: Over generations the hybrids breakdown and become incapable of reproducing.