Bran writes:
You brought up that you or I have never seen an irreducibly complex organism created, but also i have never seen anything macro-evolve either, could you please direct me to were i can read up and find out what macro-evolutionary events I am missing out on.
Edi responds: Point your browser to
Observed Instances of Speciation
Talkorigins also has another FAQ with more instances.
While macroevolution often takes a long time, it sometimes occurs quite quickly. Polyploidy is a fast evolutionary mechanism that accounts for most of the instances of observed macroevolution of which I'm aware (obligate endosymbiosis accounts for some as well). Polyploidy is the wholesale multiplication of sets of chromosomes. For example, the offspring polyploid might have 24 chromosomes from a parent specie with 12 chromosomes - or it might be the result of hybridization of two parent species, with the resulting polyploid having full (or nearly so) sets of chromosomes from both parent species.
Polyploidy results in macroevolution from one generation to the next, so we don't have to wait around for eons to see the results. Many common food plants are polyploids (e.g. bananas, wheat, potatoes). Polyploidy has also resulted in the observed macroevolution of modern species. Polyploidy is more common in plants, but it does occur in animals as well. To my knowledge, there is only one known polyploid mammal, the Red Viscach Rat - it has nearly twice the contingient of chromosomes of its close relatives - the exception is the sex chromosomes, which are not duplicates. Note that doubling of the sex chromosomes would have led to an evolutionary dead end through Natural Selection, which is probably one of the reasons polyploidy is so rare in mammals (and other organisms with similar sex chromosomes).
[revised to use little blue box quotation - thanks for the UBB pointers in Style Guides for EvC, Sylas!]
This message has been edited by Ediacaran, 05-30-2004 11:00 AM
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