Systematics and Evolutionary History of Myctophiform Fishes

Systematics and Evolutionary History of Myctophiform Fishes

Systematics and Evolutionary History of Myctophiform Fishes

 Screen Shot 2016-04-13 at 3.30.44 PMMyctophiformes (Teleostei; Myctophiformes) is an extremely understudied Order of fishes, for three major reasons.

  • Little is known about how myctophiform fishes are related at the species level, and even less is known about the biology of these fishes.
  • Myctophiform fishes are remarkable among deep-sea taxa for possessing three different types of luminous structures, providing a clear system for investigating the links between phenotypic traits and differential diversification.
  • Myctophiform fishes are well-represented as otoliths (and to a lesser extent, body fossils) worldwide, documenting extreme ecological abundance by the beginning of the Miocene, and indicating that these fishes play a critical role as a source of biomass in many food webs. This biomass is being investigated as a source for broad-scale human use.
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Top: Fresh-caught lanternfishes from the Kona coast with photophores still lit. Bottom: Short-headed lanternfish, Diaphus brachycephalus.

Body photophores in these fishes are innervated by spinal nerves, and nearly all myctophiform fishes have charismatic and taxonomically informative body photophores that bioluminesce and appear a deep blue. The intraneuronal signaling molecule in this system is a nitric oxide (nNOS), and the enzyme responsible for this reaction is thought to be a (presently undescribed) luciferase.Screen Shot 2016-04-13 at 2.56.58 PM

The speciose genus Diaphus exhibits a “headlight” complex (left), and many myctophiform fishes also exhibit luminous “stern-chasers” that are frequently sexually dimorphic in presence/absence and/or in size.

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My research focuses on resolving myctophiform intrarelationships with an eye toward understanding how these luminous traits have changed during, and how they have influenced, myctophiform evolution. My work is a synthetic combination of molecular phylogenetics, geometric morphometrics, and methods development.

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Research and article by John S. S. Denton, an AIFRB member and a Herbert & Evelyn Axelrod Research Poctdoctoral Fellow in the Department of Vertebrate Paleontology at the American Museum of Natural History.

I have worked on the systematics and evolutionary history of myctophiform fishes (lanternfishes and blackchins) and on methods for phylogenetic and macroevolutionary inference, and am currently a contributor to the NSF-funded Chondrichthyan Tree of Life (CTOL) project.

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