Changes

:::::Chris, I think you have a misconception of how common descent works.  The claim that no dog will become anything other than another kind of dog is, in fact, true, according to evolutionary theory, not a challenge of it.  The statement is essentially no different than the claim that mammals never become anything other than mammals, or eukaryotes will never be anything other than eukaryotes.  Common descent specifies that evolution happens via nested clades: groups within groups, not one group becoming another. This can be confusing because Linnean taxonomy is static, not cladistic.[[User:Plunge|Plunge]] 18:22, 20 February 2007 (EST)

:::::Chris, I think you have a misconception of how common descent works.  The claim that no dog will become anything other than another kind of dog is, in fact, true, according to evolutionary theory, not a challenge of it.  The statement is essentially no different than the claim that mammals never become anything other than mammals, or eukaryotes will never be anything other than eukaryotes.  Common descent specifies that evolution happens via nested clades: groups within groups, not one group becoming another. This can be confusing because Linnean taxonomy is static, not cladistic.[[User:Plunge|Plunge]] 18:22, 20 February 2007 (EST)

I specified that evolutionary change is the dependent variable, or Y-value, bounded by a horizontal assymptote, with time as the independent variable, or X-value.  Your second remark is entirely correct- I misused the word "species" when I meant to refer only to changes between breeds.  Observation has shown that some dominant genetic traits tend to be passed on to an organism's offspring, but alleles place boundaries on the change that can occur through this process.  It is true that it is difficult to quantify evolutionary change, since it does not appear to progress in any certain direction- another challenge to the above argument concerning the progress of evolutionary change over time.  I chose a rational graph with the dependent variable bounded by a horizontal assymptote as an illustration because the aforementioned argument seemed to assume that evolutionary change could be expressed with respect to time or reproductive cycles by a linear graph.  I chose the example of cross breeding because it is an example of the reproductive cycle being manipulated to produce maximum evolutionary change. The natural rate of change would be much slower, if indeed there were any measurable change.  My statements about a dog "remaining a dog" and not changing species were meant only as examples of the genetic limitations of evolutionary change through natural reproduction, which is generaly limited by species, though somtimes by more inclusive levels of biological classification.

I specified that evolutionary change is the dependent variable, or Y-value, bounded by a horizontal assymptote, with time as the independent variable, or X-value.  Your second remark is entirely correct- I misused the word "species" when I meant to refer only to changes between breeds.  Observation has shown that some dominant genetic traits tend to be passed on to an organism's offspring, but alleles place boundaries on the change that can occur through this process.  It is true that it is difficult to quantify evolutionary change, since it does not appear to progress in any certain direction- another challenge to the above argument concerning the progress of evolutionary change over time.  I chose a rational graph with the dependent variable bounded by a horizontal assymptote as an illustration because the aforementioned argument seemed to assume that evolutionary change could be expressed with respect to time or reproductive cycles by a linear graph.  I chose the example of cross breeding because it is an example of the reproductive cycle being manipulated to produce maximum evolutionary change. The natural rate of change would be much slower, if indeed there were any measurable change.  My statements about a dog "remaining a dog" and not changing species were meant only as examples of the genetic limitations of evolutionary change through natural reproduction, which is generaly limited by species, though somtimes by more inclusive levels of biological classification.