Phylogenetic relationships, origin and historical biogeography of the genusSprattus(Clupeiformes: Clupeidae)

Abstract

The genus Sprattus comprises five species of marine pelagic fishes distributed worldwide in antitropical, temperate waters. Their distribution suggests an ancient origin during a cold period of the earth’s history. In this study, we evaluated this hypothesis and corroborated the non-monophyly of the genus Sprattus, using a phylogenetic approach based on DNA sequences of five mitochondrial genome regions. Sprattus sprattus is more closely related to members of the genus Clupea than to other Sprattus species. We also investigated the historical biogeography of the genus, with the phylogenetic tree showing two well-supported clades corresponding to the species distribution in each hemisphere. Time-calibrated phylogenetic analyses showed that an ancient divergence between Northern and Southern Hemispheres occurred at 55.8 MYBP, followed by a diversification in the Oligocene epoch in the Northern Hemisphere clade (33.8 MYBP) and a more recent diversification in the Southern Hemisphere clade (34.2 MYBP). Historical biogeography analyses indicated that the most recent common ancestor (MRCA) likely inhabited the Atlantic Ocean in the Southern Hemisphere. These results suggest that the ancestral population of the MRCA diverged in two populations, one was dispersed to the Northern Hemisphere and the other across the Southern Hemisphere. Given that the Eocene was the warmest epoch since the Paleogene, the ancestral populations would have crossed the tropics through deeper cooler waters, as proposed by the isothermal submergence hypothesis. The non-monophyly confirmed for the genus Sprattus indicates that its systematics should be re-evaluated.

Environmental DNA reveals temporal variation in mesophotic reefs of the Humboldt upwelling ecosystems of central Chile: Toward a baseline for biodiversity monitoring of unexplored marine habitats

“…We noted that assignments to the genera Heteroclinus, which belongs to the family Clinidae, most likely correspond to the genus Myxodes, the sole genus of this family present in Chile with three species (M. viridis, M. ornatus, and M. cristatus). We also noted that sequences assigned to Sprattus most likely correspond to the genus Strangomera, the latter without reference sequences for 16S in public databases, but phylogenetically close to the northern hemisphere Sprattus (Canales-Aguirre et al, 2021). Finally, some of the unassigned ASVs may correspond to undescribed mesophotic species.…”