Replies

"By the time the salamanders reached the southernmost part of California, the separation had caused the two groups to evolve enough differences that they had become reproductively isolated. In some areas the two populations coexist, closing the "ring," but do not interbreed. They are as distinct as though they were two separate species. Yet the entire complex of populations belongs to a single taxonomic species, Ensatina escholtzii. "

as i posted variation within a species can be explained by
evolution hypothesis.. no argument there

however we are talking about basically similar salamanders here (ring) not interbreeding from what i can deduct due to not changes in morphology of physical characteristics such as sex organs but in habit of mating.

A horse can produce a mule is that evolution?

i can understand those who would propose this ring data shows evolution - it well may- but you do not have a
mule at the far end of the ring you still have a salamander with unique breeding habits.

what am i missing??

A horse can produce a mule is that evolution?

That should read:
"A horse can still produce a mule..."

I'm not sure if this is scientifically correct, but the principle involved is the "differentiation" of the species of horse and donkey..

At some point, horses and donkeys split into two different breeds or species..
For a very long time, there was plenty of interbreeding, but over eons, the two species became less and less alike..
Such matings became "accidental" until man came along and started interbreeding on purpose..
Without human interference, ( and maybe in spite of it, ) horse and donkey will eventually be unable to interbreed at all..
Result,.. No more Mules..
While still closely "related" enough to produce offspring, they are generally infertile.
Occassionally a horse/jenny or donkey/mare offspring will be fertile and able to produce offspring..

What am I missing?

I think what is missing is Time.

The Salamanders have not remained distinct for a long enough period to completely become two different "species", if that's the right word..

Something similar was reported recently concerning birds that split their migration around the Himalayan mountain range.. ( National Geographic? )
Those that went North and East can interbreed...
Those that went North and West can interbreed..
Those IN the Northeast and Northwest cannot..
The two branches even have developed different coloration, as well as mating calls and habits..

Given time, the salamanders will become distinct branches of their species, with more than mating habits to differentiate them.. physical characteristics will eventually develop as well, to make identification of qualified mating material easier to identify..

we are talking about basically similar salamanders here (ring) not interbreeding from what i can deduct due to not changes in morphology of physical characteristics such as sex organs but in habit of mating.
i can understand those who would propose this ring data shows evolution - it well may- but you do not have a mule at the far end of the ring you still have a salamander with unique breeding habits.

what am i missing??

The fact that these two populations are reproductively isolated.

  C - D
 /     \
B       E
 \     /
  A | F

A breeds with B, B breeds with C, C breeds with D, D breeds with E, E breeds with F, but A and F do not breed.

They are still technically classified as a single species, but incremental changes along the continuum have accumulated to the point that the ends of the ring function as separate species. Each end is free to drift (genetically speaking) independently of the other. What difference does it make if they don't breed because of coloration or sex organs or a funky mating dance? They are now separate and will in all likelihood continue to diverge.