Impacts of Outgroup Selection on Australoheros Species Delimitation in bPTP Analyses
This study performs a methodological evaluation of the Bayesian Poisson Tree Processes (bPTP) method for species delimitation in the genus Australoheros. We hypothesize that increasing the phylogenetic distance of the outgroup used decreases the number of delimited Operational Taxonomic Units (OTUs). We test the impact of different outgroups, with different phylogenetic positions in a dataset from the most recent taxonomic study about Australoheros. We reanalyzed this dataset while following the assumptions of the bPTP method, which had previously been violated. We tested outgroup-distance effects on species delimitation by using seven distinct outgroups from distinct genera, tribes and subfamilies of the Cichlidae, totaling eight COI and eight CYTB matrices. COI analyses delimited between 15 and 9 OTUs; CYTB analyses between 24 and 14, showing consistent OTU reduction as outgroups became more phylogenetically distant. Thus we consider that the use of phylogenetically distant outgroups may reduce the adequate recovery of OTUs.
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