Contributions to Zoology, 69 (4) (2000)Alexandr P. Rasnitsyn: Testing cladograms by fossil record: the ghost range test

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Conclusion

The above observations indicate that the total amount of ghost ranges displayed by different phylogenetic trees for the same set of taxa does allow us to compare and evaluate the cladograms forming the background of these trees. Moreover, the results of application of the method are understandable and possible to explain, at least in part. That the cladogram from Rasnitsyn (1988) fits better to the fossil record than the majority of others, depends at least partially on the appreciation of mother and daughter groups in additional to the sister groups, these latter being the only legitimate ones in cladistics. At the same time, testing of the cladogram by Brothers and Carpenter (1993) indicates that the high score received by Rasnitsyn’s (1988) cladogram from the present test is not a straightforward result of the method used there, i.e., the making of a cladogram by the method of Hennig (“paper and pencil” approach) instead of the automatic parsimony calculation, and an appreciation of the ancestor and descendant taxa.

Several ways to further development of the ghost range method may be proposed. The most evident one is the calculation of the length rather than the simple count of ghost ranges: this would make the method more precise. However, there is yet another possibility. As proposed, the ghost range method is designed to test competing cladograms in regards to their congruence with the fossil record. Instead, it might be found useful to use the geochronological data directly in the parsimony calculation, to include the information from fossil record into the cladistic procedure. However, even it its simplest form, the ghost range method might be a useful test for cladograms.