BIOGEOGRAPHY AS A MEANS OF TESTING PHYLOGENETIC HYPOTHESIS REGULARITIES

Tree Thinking usually considers that phylogenetic hypotheses summarized by cladograms are being constantly tested via reciprocal illumination (i.e., inclusion of new data). However, recent works demonstrated that the inclusion of new data such as new species, specimens or phylogenetic characters are only means of fulfilling the requirement of total evidence, and thus not a proper test of the hypothesis. In fact, the regularities, treated here as the consequence of the proposed causes for the hypothesis, are not even observed/created. As a historical science, the phylogenetic hypotheses must be tested via "smoking gun" procedures where the regularities will be appropriately recognized. Also, the phylogenetic hypotheses should enable the mutual exclusion of competitive hypotheses and provide test evidences for those with more regularities recovered. The present contribution unprecedently aims to demonstrate how and why biogeography could be used as one way to recover regularities that should be used as test evidence for phylogenetic hypotheses. The phylogenetic hypotheses are compound hypotheses accounting for the origin and fixation of the phylogenetic characters and the populational split (temporal/spatial) of the hypothetical ancestral species. Biogeographical studies can provide regularities regarding the populational split test evidences for at least the existence of a common ancestral population between studied species that are split by a biogeographical event (e.g., vicariance, dispersion, fragmentation). Additionally, biogeographical hypotheses bring light to the paleoenvironment, which could also provide further regularities for the origin and fixation of studied characters. For example, lets consider the Gavialoidea clade, which in some propositions comprises two sister-groups, the South American gavialoids (Gryposuchinae) and the Indian gavialoids (genus _Gavialis_). A test prediction could be a vicariant hypothesis including Antartica, or a dispersive one via Africa. The prediction of new specimens related to the known species of any of the supramentioned clades, together with biogeographical process explanations, would provide enough regularities to exclude one of them and strengthen the other. Therefore, biological systematics should venture in the elaboration of more elaborated phylogenetic hypotheses than mere synapomorphies in clade branches and start to predict at least biogeographical regularities, being a way to properly test our hypothesis. [CAPES]