PhD: Tackling the ‘teleost gap’

Teleosts are a staggeringly diverse and abundant group, accounting for 99% of the 30,000 living species of actinopterygians. The early evolution of the group, and the assemblage leading to it, is poorly understood, despite a wealth of three-dimensional fossils belonging to a number of taxonomically diverse and anatomically disparate groups (e.g. Arratia 2013, Giles et al. 2016). Re-evaluation of key representatives of these radiations will resolve questions of phylogenetic affinity and character evolution leading to the living teleost radiation. Time-calibrated molecular phylogenies suggest that the living teleost radiation originated around 225 million years ago, but the oldest fossil evidence is nearly 75 million years younger (Near et al. 2012, Giles et al. 2017). Revisiting stratigraphic periods in which teleost fossils are expected but not identified may inform the use of fossils to calibrate nodes in molecular phylogenies, with potential downstream effects for the ‘teleost gap’. Once a robust hypothesis of phylogenetic relationships has been established, macroevolutionary patterns relating to teleost success, including rates of speciation and diversification, hypotheses of dispersal, and selective extinction pressures, may be investigated.