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Author Topic:   Speciation + Evolution = More Diversity
RAZD
Member (Idle past 1405 days)
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Joined: 03-14-2004


Message 1 of 2 (493265)
01-07-2009 8:26 PM


Evolution after Speciation
The scene: sitting at computers all over the world ...
"Why don't creationists understand evolution -- it is so simple," the evolutionist wails:
  • Evolution - the change in hereditary traits in populations from generation to generation - is an observed and documented fact, a process that occurs constantly in the natural world around us, and
  • Speciation - the division of parent populations into reproductively isolated daughter populations - is also an observed and documented fact, a process that occurs frequently in the natural world around us.
These two simple processes are sufficient to explain the diversity of life we know, from the world around us, from history, from prehistory and archeology, from geology and physics and paleontology and the fossil record, and from chemistry and the genetic record.
We can even see how evolution causes speciation with Ring Species:
  • the species forms a band made up of several varieties around some barrier to their survival ability,
  • each of the varieties has slightly different hereditary traits from their neighbors,
  • each reproduces with their neighbors in hybrid zones that show a mixing of the hereditary traits of the two neighbors, except that
  • when they meet on the other side of the barrier, the two ends do not mate.
Evolution results in different hereditary traits developing in each of the areas dominated by the different varieties, differences that do not hinder mating until they reach a certain threshold - the difference between the end varieties.
Remove any one of the intermediate varieties, so that the band is broken, and you have two distinct species.
We now have more species than before, so life is more diverse. It is so simple:
Evolution + Speciation = Diversity
"But," replies the creationist, "this does not tell us anything we do not know. Species always reproduce after their own kind, a dog will always be a dog. You may end up with several species of dogs, but they will still be dogs. This does not tell us how new forms of life are evolved: when does a dog become something else? Evolution says that mammals evolved from marsupials, so when will a kangaroo evolve into a giraffe? This kind of change is not seen in the fossil record, nor has it been observed by man, so how can you say this happens?"

This little scenario depicts, I believe, the state of many debates between creationists - people that predominantly use faith to understand the world - and "evolutionists" - people that predominantly use science to understand the world.
See Evolutionary Theory Explains Diversity, Dogs will be Dogs will be ??? and What i can't understand about evolution.... threads for examples.
Where does "large" change come from? - the change that makes giraffes so different from kangaroos? Simple:
  • Speciation - the division of parent populations into reproductively isolated daughter populations - is also an observed and documented fact, a process that occurs frequently in the natural world around us, and
  • Evolution - the change in hereditary traits in populations from generation to generation - is an observed and documented fact, a process that occurs constantly in the natural world around us.
Speciation + Evolution = More Diversity

After speciation has occurred, the daughter populations no longer share genes through reproduction, and they are free to evolve completely different traits. The likelyhood is high that one of them will become quite different, either to inhabit a new ecology that the other is not as well suited to (could have caused the original split), or to make use of the existing ecology in a different way, and this will lessen competition between the two species rather than drive one to extinction.
Continued evolution of daughter populations along different ecological paths results in increased diversity - difference - between them over time. That is how the small amount of difference we seen below can become the amount of difference we see between other bird species.
Greenish warblers
quote:

Continued evolution causes more change - in each population, from generation to generation to generation.
That should be enough for starters. There is more to discuss about where change occurs, but this is long enough for now.
This thread is about evolution after speciation.
Enjoy.
Edited by RAZD, : color, subtitle

we are limited in our ability to understand
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AdminNosy
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Message 2 of 2 (493267)
01-07-2009 8:40 PM


Thread copied to the Speciation + Evolution = More Diversity thread in the Biological Evolution forum, this copy of the thread has been closed.

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