Molecular phylogenetics, morphological cladistics, and fossil record

Abstract

Paleontological fit of different kinds of cladograms is considered using the ghost range method, the ghost range being the time gap between dates of supposed and paleontologically confirmed appearance of a taxon. The absolute and relative length of total ghost ranges in the published morphological and molecular cladograms and, in some cases, traditional (‘intuitive’) cladograms were calculated. Orders of winged insects as well as families of some of these orders were the terminal taxa of the cladograms (in all, 42 cladograms for 14 sets of terminal taxa). A new index is proposed to assess the relative amount of ghost ranges: GRI = 1-L0/LM, where L0 is the sum of ghost ranges in a particular cladogram and LM is the maximum possible sum of ghost ranges in a cladogram with the same set of terminal taxa. As in the previous studies (Rasnitsyn, 2000, 2005), calculations showed the intuitive cladograms to be clearly superior to both molecular and morphological ones in their stratigraphic fit. Another result, namely that molecular cladograms showed no advantage over morphological cladistics, was unexpected and apparently unexplainable. Additionally, the hypothesis of character devaluation resulting from computerized cladistic procedures (Rasnitsyn, 2002) was directly supported for the first time by our calculations.