Hey Dean - this non-linear business
12-04-2005, 06:32 AM
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Hey Dean - this non-linear business
There you go getting all linear on me. Evolution only appears to be linear in hindsight. Mutations are random events, so the term degeneration doesn't apply, as mutations don't move in any particular direction. Most mutations are either directly or indirectly fatal, but in relatively rare instances a mutation will provide an organism with an advantage to survive within its environment
1. I think the insect thread had been sufficiently hijacked already.
2. A new thread seemed a less linear approach.
In trying to wrap my mind around this process, I think maybe I'm starting to get it. Here goes:
Let's start with two organisms which produce offspring as they are genetically driven to do. These offspring continue to produce more offspring, generation after generation.
After many, many iterations we would expect to see one or all of the following:
One or more groups that are essentially unchanged from the original parents.
One or more groups whose mutations were unfavorable and they eventually died out.
One or more groups which are so utterly changed that they would be incapable of reproducing with the original parent. At no point during the process did they become so different as not to be able to reproduce with many of the previous generations but after enough time and gradual change they emerge as a new and different species.
I know I'm ignoring the other factors (selection, environment, etc.) involved but is this the general idea?
12-04-2005, 07:08 AM
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Originally Posted by raymo19,Dec 4 2005, 11:32 AM
In trying to wrap my mind around this process, I think maybe I'm starting to get it. Here goes:
Let's start with two organisms which produce offspring as they are genetically driven to do. These offspring continue to produce more offspring, generation after generation.
After many, many iterations we would expect to see one or all of the following:
One or more groups that are essentially unchanged from the original parents.
One or more groups whose mutations were unfavorable and they eventually died out.
One or more groups which are so utterly changed that they would be incapable of reproducing with the original parent. At no point during the process did they become so different as not to be able to reproduce with many of the previous generations but after enough time and gradual change they emerge as a new and different species.
I know I'm ignoring the other factors (selection, environment, etc.) involved but is this the general idea?
Let's start with two organisms which produce offspring as they are genetically driven to do. These offspring continue to produce more offspring, generation after generation.
After many, many iterations we would expect to see one or all of the following:
One or more groups that are essentially unchanged from the original parents.
One or more groups whose mutations were unfavorable and they eventually died out.
One or more groups which are so utterly changed that they would be incapable of reproducing with the original parent. At no point during the process did they become so different as not to be able to reproduce with many of the previous generations but after enough time and gradual change they emerge as a new and different species.
I know I'm ignoring the other factors (selection, environment, etc.) involved but is this the general idea?
A mutation may be so slight and insignificant that it is never expressed within the phenotype and has no effect on the organism in terms of survival.
A mutation may be so severe that it precludes the possibility of viable offspring, which is probably the most common type of mutation.
The third possibility you present is the process known as speciation which is essentially how evolution works. Some type of isolation, usually geographic in nature, of a group of individuals within a population of a species is required for a mutation to take root within that sub population and create a new species. Otherwise, a "dilution" of that genotype will occur which will usually not allow the mutation to gain dominance.