Gondwana Biogeography: the study case of Osteoglossiform fishes (Teleostei, Osteoglossomorpha)

Abstract

Osteoglossiformes is one of the oldest teleost lineages, with a wide geographic distribution, making this group an interesting subject for systematic, biogeographic and evolutionary studies. Currently, living species of this order are found in several rivers and lakes in South America, Africa, Asia and Australia. Such wide distribution probably contributed to the diversity of the group, which might be linked to the capacity of species to adapt to a large variety of environments. Given their very ancient origin (~227 Mya), the current distribution of Osteoglossiformes could be the result of vicariant events after the break-up of the southern supercontinent Gondwana. However, the fossil record and recent studies incorporating molecular dating do not fully support this theory. Similar patterns have been found in other teleost and animal lineages, challenging the Gondwana vicariance hypothesis. The present project seeks to generate a robust phylogenetic framework for Osteoglossiformes, using for the first time Next Generation Sequencing of ultra-conserved element nuclear loci (UCEs) This data was recently developed during a five months stay at Dr. Brant Faircloth´s lab (Lousiana State University, USA) and is currently being analyzed to generate hundreds to thousands of loci. This sequence data was obtained from an extensive sample including representatives from all families of the Osteoglossiformes fish order. Our dataset will be used in Bayesian biogeographic inferences to reconstruct the spatiotemporal evolution and diversification history of the Osteoglossiformes. We will test potential correlates of speciation, extinction, and geographic migration with Gondwana geological history using trait, environmental and time-dependent macroevolutionary models. Further, we will carry out a meta-analysis based on a thorough phylogenetic literature review on Gondwana biogeography We will evaluate potential biological and environmental drivers that might explain why different taxonomic groups achieved their current "Gondwanic" distribution via dispersal or vicariance. This is the first time the Gondwana hypothesis will be studied at such large and in-depth phylogenetic scale. The project will integrate a team of researchers from all five continents, which will help to ensure the success of the proposed research. (AU)