revolution

James Lyons-Weiler weiler at ERS.UNR.EDU
Wed Oct 2 07:44:02 CDT 1996


On Wed, 2 Oct 1996, Tom DiBenedetto wrote:

> Advice to R. Zander:
> 1. Understand that the "Hennigian algorithm" is not a model of
> evolution

I disagree.  The "Hennigian algoritm" is model of evolution that excludes
the following possible models:

        1) Multiple, instantaneous speciation events (hard polytomies);

        2) Very high rates of anagenetic evolution (i.e., all characters
        have changed an infinite number of times on each internal node,
        and have retained NO information about genealogy of the remnant
        organisms;

        3) Convergence as a process over synapomorphy;

        4) The evolution of characters for which one has data has been
        non-independent (watch the double negative here, sorry);

        5) The evolution of characters among lineages has been
        non-independent;

        6) Polymorphism inherited through more than one furcation.

When one approaches their data with cladistics (or max pars, and other
methods), one usally is not suspecting that any of these six alternative
models of evolutionary process have been at work, messing up cladistic
hierarchy in the distribution of character states among surviving and
sampled data.

James Lyons-Weiler




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