title: The presence of lateral photophores correlates with increased speciation in deep-sea bioluminescent sharks.
abstract: The vast majority of species within the lanternshark genus Etmopterus harbour complex luminescent markings on their flanks, whose functional significance has long remained obscure. Recent studies, however, suggest these enigmatic photophore aggregations to play a role in intraspecific communication. Using visual modelling based on in vivo luminescence measurements from a common lanternshark species, we show that etmopterid flank markings can potentially work as a medium range signal for intraspecific detection/recognition. In addition, using molecular phylogenetic analyses, we demonstrate that the Etmopterus clade exhibits a greater than expected species richness given its age. This is not the case for other bioluminescent shark clades with no (or only few) species with flank markings. Our results therefore suggest that etmopterid flank markings may provide a way for reproductive isolation and hence may have facilitated speciation in the deep-sea.
authors.affiliation: Laboratoire de Biologie Marine, Earth and Life Institute , Université catholique de Louvain , Louvain-la-Neuve 1348, Belgium.
authors.forename: Julien M
authors.initials: JM
authors.lastname: Claes
authors.affiliation: Lund Vision Group, Department of Biology , Lund University , Lund 22362, Sweden.
authors.forename: Dan-Eric
authors.initials: DE
authors.lastname: Nilsson
authors.affiliation: Laboratoire de Biologie Marine, Earth and Life Institute , Université catholique de Louvain , Louvain-la-Neuve 1348, Belgium.
authors.forename: Jérôme
authors.initials: J
authors.lastname: Mallefet
authors.affiliation: Bavarian State Collection of Zoology , Münchhausenstrasse 21 , München 81247, Germany.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Straube
keywords: bioluminescence; diversification; evolution; shark; visual detection