Where did good come from?

[Roxolan]

Originally Posted by c'est la vie

Not at all.
Let's take the 'flooded river' scenario.
It would not necessarily separate any groups of critters living in the river itself.
Birds would not have a problem with it. Same with many species of insects.
Many plants might still be able to continue as before given that wind would travel across a flooded river.
Larger animals might easily find a way to cross, just having to go farther to do it.

As I said before, complete separation is not required - it merely speeds up the process. Genetic drift would still occur. See ring species for example. Or better, read some of the stuff from this website, written by professors from the University of Berkley.

Originally Posted by c'est la vie

They affect a relatively small area when you get down to it.
The really big events , a volcano that kills off half the continent, an island that breaks off the mainland, are so rare as to be an insignificant percentage.
Also, most of the supposed events do not last long enough to allow speciation to occur.
When was the last time you saw a river remain flooded for more than 1 year?
A forest fire burn in the same area for more than a few days (any given spot is burned and the fire moves on, animals started coming back into the burned area fairly quickly)?

Assertions, assertions. The thing is, neither of us know enough about the specifics to make serious claims about how common or rare specific geological events are. It so happens that the majority of evolutionary biologists (you know, people who actually study that stuff) consider geographic separation to be a common cause for speciation. Can you find any qualified biologist supporting your oppinion in a peer-reviewed publication?

(By the way, the "forest fire" idea wasn't mine and I already said it sounded implausible. Could you please stop using that strawman?)

Originally Posted by c'est la vie

A volcano that erupted for a year in duration?

Do you realize that a single volcanic eruption can dramatically alter the landscape? It can create a mountain or an island, alter the course of rivers, create or destroy lakes, change the characteristics of the ground around it (thus transforming vegetation)... And of course plenty of volcanos erupt more than once.

Originally Posted by c'est la vie

Many of the speciation types listed rely on partial or total separation.

We've mostly been discussing total separation. Once you get down to partial separation, you're really talking about an arbitrary definition because anyone can say 'well I can imagine a scenario in which there'd be more interaction, so these groups are *partially* separated'

Everything becomes *partial separation* at that point. It is in the eye of the beholder.

I admit that there are tricky cases (see ring species again). But in general, your affirmation is ludicrous. Obviously you could not extract a mathematically precise "percentage of separation", but anybody studying a species' mating habits can easily see what are normal conditions and what aren't. Once again, the language analogy may help you, if you actually try and think about it.

Originally Posted by c'est la vie

At that point you've really given yourself an unfalsifiable theory. Which means it's not scientific.

What theory are we talking about here? Because if you refer to allopatric speciation, it can be infered by countless pieces of evidence. Basically whenever you study wildlife (both past and present) in places separated (or once separated) by a geographical barrier of some kind.