Biotic crises and morphological change, the WAPUM method applied to marine and terrestrial taxa: bivalves and insects

PETRULEVICIUS, J. F., NEL, A. Y ROS-FRANCH, S.

Mendoza

Congreso; 4th International Palaeontological Congress; 2014

The analysis of global, planetary, faunistic and floristic changes during the Phanerozoic eon is very important to define the stratigraphic divisions and the major crises of biodiversity. The Wagner Parsimony Applied to Palaeosynecology Using Morphology (WAPUM) consists in the application of the Wagner Parsimony algorithm to classify the geological periods using morphological characters instead of taxa. In the WAPUM a character is ?presence versus absence of species bearing a morphological structure?. With this method we avoid the difficulties related to the monophyly/paraphily of the taxonomic groups used in more traditional approaches. The method is applied here on morphological characters of bivalves and insects. Study of marine biotic crises was a classical and historical scope via the typological methods for centuries. For the first time, we applied the WAPUM method to a marine group, the Pectinoidea sensu Waller. Preliminary results indicate strong morphological changes through the Permo/Triassic (P/T) boundary but also an interesting grouping of the three Paleozoic periods considered: Devonian, Carboniferous and Permian, which implies a characteristic Paleozoic morphology for the Pectinoidea. Other morphological changes occur between the Lower and Middle Triassic but not in the Cretaceous/Tertiary (K/T) boundary. From the terrestrial taxa analyzed, especially the Odonatoptera, we noticed no significant morphological changes during the P/T and K/T boundaries. However, there were important changes at the Lower-Upper Cretaceous boundary, probably linked to the angiosperm diversification and the eutrophication of freshwater environments. Although our results are preliminary, and the method has to be applied to more taxa, the groups analysed have dissimilar histories and seems that they have been affected by different events. We consider that the application of the WAPUM to other groups could help to confirm or object the currently available scenarios for the global changes in the evolution of past diversity and disparity of organisms (major changes or global crises of diversity).