Background and aims
Incongruences in the biogeography of aquatic taxa in southern Australia have existed due to the non-reciprocally monophyletic nature of the pygmy perches (Percichthyidae). In addition to their complex biogeographic history, pygmy perches also represent a threatened group with confusing taxonomy. However, the current understanding of their biogeography and phylogenetic relationships is based on limited genetic datasets.
We present the first study of the phylogenetic history of pygmy perches using genome-wide data. This work aims to reconstruct the phylogeny of pygmy perches and address biogeographic incongruences and cryptic diversification using a combination of phylogenomic approaches and a species delimitation framework. We also present a molecular clock and divergence time analysis, using the biogeographic barrier represented by the Nullarbor Plain as a calibration point.
The overall topology and biogeographic patterns inferred by previous studies was supported with the genome-wide phylogeny obtained. It appears that the unique biogeographical patterns displayed by pygmy perches represent a biological reality, creating significant questions in the understanding of the biogeography of southern Australian freshwater organisms. Furthermore, the finding of previously unknown species identities demonstrate that the already threatened pygmy perches may be even more susceptible to extinction than previously thought. As such, these results have substantial implications for improving conservation legislation of pygmy perch lineages.
This study highlights the need for robust studies using genomic datasets to understand cryptic speciation and clarify taxonomy in pygmy perches, and for comparative analyses of other codistributed organisms to assess congruency of relevant biogeographical patterns.