As Cladistics and "Eclecticism", Aves, paraphyly flow on

[John Grehan]

>The rocks are pretty obvious, although no one seems to want to look at
>them.  For example, we all know (although some insist the contrary) that
>evolutionary events are not exclusively dichotomous.  This is a simplifying
>assumption that is necessary for the technique to work well, but our
>favoured model of speciation (allopatry) could easily generate multiple
>simultaneous branching events.  Sympatric speciation may be locally
>dichotomous, but is also open to the generation of multiple species from a
>single ancestral species (as recent work on frogs demonstrates
>nicely).

If one read the panbiogeographic literature it would be apparent that in this
field at least the question of multiple 'simultaneous' branching events is
not only addressed, but accepted as a common normal event with the result
that there can be some interesting geographically incongruous biological
relationships (i.e. the nearest geographic neighbor in a vicarious non-disjunct
series is not necessarily most closely related in biological characters).
The most
extreme form is even given its own name - wing dispersal (i.e. the 'wings'
of a
distribution range are more closely related than either wing is to the 'center'

  More
>importantly, it is becoming increasingly obvious that reticulate evolution
>is important in many, if not most, sexual groups.

Actually I would suggest that it has been as 'obvious' all along - just not
popular with
traditional evolutionary models (I would call them 'Darwinian' models -
pejorative or
not). Croizat referred to reticulate evolution as character recombination.

John Grehan