WIDESPREAD TAXA, SYMPATRY, DISPERSAL, AND AN ALGORITHM FOR RESOLVED AREA CLADOGRAMS

It is argued that in area biogeographical studies, the information con tent of widespread taxa is comparable to that of endemic taxa; widespr ead taxa should therefore be treated under Assumption 0. For areas of sympatry (redundant distributions) on the other hand, Assumption 2 is warranted because dispersal must always be invoked to explain sympatry . It is argued that all occurrences in an area of sympatry should be t reated equally, regardless of whether the taxa are widespread or endem ic, and regardless of whether the taxa occupy terminal or basal positi ons on the cladogram. An algorithm for translation of taxon-area clado grams into resolved area cladograms under these conditions is given. A s an example, this algorithm is applied to inocelliid snakeflies and g errine pondskaters. (C) 1996 The Willi Hennig Society.