First molecular timetree of billfishes (Istiophoriformes: Acanthomorpha) shows a Late Miocene radiation of marlins and allies

Abstract

Billfishes (Order Istiophoriformes) represent a major radiation of pelagic predators in most tropical and temperate ecosystems. This group includes species that are commercially harvested, and several species that are considered the most prized of game fishes. Like other pelagic teleost groups, relatively little is known about the mode and tempo of billfish evolution compared to groups that predominantly inhabit coastal and benthic ecosystems. We generated a time-calibrated molecular hypothesis of the timing of billfish evolution using 10 loci and utilizing the rich fossil record dating back to the Early Eocene. Our timetree infers a Late Cretaceous origin for the istiophoriforms, with istiophorid diversification beginning in the Middle to Late Miocene (~17 Ma), but with most splits having occurred since the Pliocene (~5 Ma). This timing of diversification coincides with the radiation of tunas, and may have been driven by the establishment of modern upwelling regimes across the world’s oceans.