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Anything that reduces or eliminates gene flow between two populations is a type of isolation. The first thing that comes to my mind is an island versus mainland situation where part of a population somehow got to an island (like rats from a wrecked ship) and couldn't get back to the mainland. Another is through dispersal. For example, when a group of American finches colonized the Hawaiian islands, the group became geographically isolated from other populations of the species. These finches eventually gave rise to the 23 species of Hawaiian honeycreepers.
A real common example that most people don't even bother to think about is habitat destruction caused by humans. For example, the Chrysopsis floridana (a species of golden aster) only grows in the Florida scrub habitat. Every time a new housing development goes up, the population of plants gets separated to the point where some populations are so far away from each other that there is no way for cross pollination to occur.
Rats on a wrecked ship?
You are kidding right?
First, the inbreeding issue that I raised would certainly be relevant there.
In addition, I thought speciation took llllllllllllllllllooooooooooonnnnnnnnnnggggggggg ages to occur.
How long has man been travelling across the seas? How many speciation events could you possibly attribute to this. C'mon.
Habitat destruction by humans?
Again, really?
Man has been able to 'destroy' an entire ecosystem for *maybe* one or two generations.
Are we seriously going to discuss it as a cause of speciation for the past however many million years you want to go back?
C'mon now Eresh.
You've got MILLIONS if not BILLIONS of speciation events to account for.
Give me an example of geographic isolation (where individuals cannot travel between the populations, preventing the two populations from interbreeding), that could have reasonably caused a large number of speciation events.
Man has been able to 'destroy' an entire ecosystem for *maybe* one or two generations.
They are beginning to think that the inhabitants of Easter Island destroyed their ecosystem by cutting down all the trees in production their giant rock "tiki" statues....
First, the inbreeding issue that I raised would certainly be relevant there.
In addition, I thought speciation took llllllllllllllllllooooooooooonnnnnnnnnnggggggggg ages to occur.
How long has man been travelling across the seas? How many speciation events could you possibly attribute to this. C'mon.
Habitat destruction by humans?
Again, really?
Man has been able to 'destroy' an entire ecosystem for *maybe* one or two generations.
Are we seriously going to discuss it as a cause of speciation for the past however many million years you want to go back?
C'mon now Eresh.
You've got MILLIONS if not BILLIONS of speciation events to account for.
Give me an example of geographic isolation (where individuals cannot travel between the populations, preventing the two populations from interbreeding), that could have reasonably caused a large number of speciation events.
If you are going to attempt a rebuttal, then you need to bring something substantive into your argument. To do otherwise is a complete waste of time and demonstrates extremely poor discourse skills.
Every one of my examples is well documented (as in concrete evidence), and a person's mere unwillingness to accept it does not constitute a decent counterargument.
So you visited Wikipedia and yet could not find any example?
Quote:
One example of natural speciation is the diversity of the three-spined stickleback, a marine fish which, after the last ice age, has undergone speciation into new freshwater colonies in isolated lakes and streams. [...]
Allopatric speciation may occur when a species is subdivided into two large populations (dichopatric or vicariant speciation) for example by plate tectonic or other geological events, or when a small number of individuals colonize a novel habitat on the periphery of a species' geographic range (peripatric speciation). [...]
Island genetics, the tendency of small, isolated genetic pools to produce unusual traits, has been observed in many circumstances, including insular dwarfism and the radical changes among certain famous island chains, like Komodo and Galápagos, the latter having given rise to the modern expression of evolutionary theory, after being observed by Charles Darwin. Perhaps the most famous example of allopatric speciation is Darwin's Galápagos Finches.
Quote:
Originally Posted by c'est la vie
Picture this poor group of critters.
A mountain range springs up in the middle of them one day, forever separating them into two groups.
lol
You do realize that evolution is slow, right? Have you ever heard it described in terms of geological time-scale? (hint hint)
If you are going to attempt a rebuttal, then you need to bring something substantive into your argument. To do otherwise is a complete waste of time and demonstrates extremely poor discourse skills.
Every one of my examples is well documented (as in concrete evidence), and a person's mere unwillingness to accept it does not constitute a decent counterargument.
Rats on a sinking ship is the best you can do then, eh?
Well, I have to say I'm not surprised.
Evolutionists have millions (probably billions) of 'speciation events' to account for, and geographic isolation is not gonna cut it.
How many catastrophic events have separated entire populations of critters for the llllllllllllllllllllllllllloooooooooooooonnnnnnnnn nngggggggggggg ages required for speciation?
I've read other discussions where examples like 'a flooding river' are given. How long did it stay flooded?
Others have told me a group could simply 'wander away' from the main group and not return. Would this really prevent any members from interacting for lllllllllllooooooooonnnnnnnnngggggggggg ages? It must have been quite a stroll!
And of course my favorite example: the sudden appearance of a mountain or mountains that separates populations. It's like the Berlin Wall was built overnight, only more so.
I think a discussion of rats on a sinking ship is completely in order.
Any other evolutionists want to chime in as you disembark?
Yes and that's the point. Mountains don't pop up in a day, do they?
To say that 'mountain building' would cause geographic separation of two groups of critters is comical to say the least.
Not entirely, there are primate groups that are seperated my mountains. I remember reading about two groups of chimps that are seperated by a range in Africa. Mountains may take years to "build" but if the groups aren't migrating all that much (or at all). They were already seperated, as in being hundreds of miles apart; but now that there are mopintains, they aren't going to mingle any time soon.
Plus, it isn't just mountains that seperate a species. removal of forests can drive a species apart. A big forest fire, volcanic eruption, flood or any natural disaster could force a species to split.
Also consider bodies of water. A giant river could keep a species seperated.
Yes and that's the point. Mountains don't pop up in a day, do they?
No they don't, and neither do species.
A species live on a large area. Over a very long period of time, geological events modify that area, dividing it into two parts. Maybe a mountain rises in the middle, or maybe a piece suffer erosion and becomes an island. It gets harder and harder for members of that species to move from one part to the other, and eventually it becomes completely impossible. Genetic drift sets in, and the group on one part evolve differently from the one in the other part. Millions of years later, the two groups are two species.
After the eruption is over why can't the critters get back together?
Forest fire and flood same question.
Do these events really separate groups of critters for millions , or even thousands of years?
C'mon.
You guys are reaching.
But I can understand why since the floor is slipping out from under you.
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