[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: Quick cladistics question



Jonathon Woolf wrote:
>I don't know very much about cladistics, but based on what I do know the
>above seems to be an inherently contradictory position.  OK, you define
>clades based on relationships.  How do you define relationships?  How
>else can you define relationships except by physical characteristics?   
        No, you *discover* hypothesized relationships based on
characteristics. You may define anything based on the relationship "the
sommon ancestor of A and B and all of it's decendants", then you must use
characteristics to determine who you think belongs in that group.

>Further, why would you _want_ a system that is "more stable against new
>discoveries?"  Shouldn't the classifications reflect all available
>data?  
        George was referring to som basic questions concerning apomorphy
based clades. If the apomorphy is convergent, how do you deal with the
question of where it developed "first", and which group with the apomorphy
is the real group. There are "simple" ways to resolve this issue, but I
doubt anyone is interested.
----------------------------------------------------------------------------
      Jonathan R. Wagner, Dept. of Geosciences, TTU, Lubbock TX 79409
            Web Page:  http://faraday.clas.virginia.edu/~jrw6f