Under this model evolutionary change is confined to shorter time spans and small isolated populations in order to account for the lack of transitional forms among the lower taxa. Lower taxon-level punctuations, however, require numerous transitional steps to produce the disparity of the higher taxa. This model also predicts that the increasing diversity of the lower taxa should precede the disparity of the higher taxa.
Copyright © 1998 Art Battson. All rights reserved. International copyright secured.