Culminating Project Title
Evolutionary Relationships and Evolution of Body Shape of the Deep-Sea Hatchetfishes (Stomiiformes: Sternoptychidae).
Date of Award
Culminating Project Type
Biological Sciences - Ecology and Natural Resources: M.S.
College of Science and Engineering
Matthew P. Davis
Matthew A. Tornow
Jennifer Y. Lamb
Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.
Keywords and Subject Headings
Phylogenetics, Geometric Morphometics, Systematics, Marine, Bioluminescence, Hatchetfishes
Within the Actinopterygii (ray-finned fishes), the Stomiiformes (dragonfishes and their allies) include 444 species of fishes found in pelagic deep-sea habitats world-wide. Within Stomiiformes, the family Sternoptychidae (deep-sea hatchetfishes) includes 78 species within ten genera. The deep-sea hatchetfishes all possess ventral bioluminescent photophores, which are hypothesized to be used for camouflage in the deep sea. The sternoptychids are commonly known for having deep bodies that resemble a hatchet, although seven genera in this family exhibit a more slender-body. Previous phylogenetic studies have examined the evolutionary relationships of this family of fishes predominately based on morphological data. Few molecular-based studies have examined the evolutionary relationships of the sternoptychids. This study investigates the evolutionary relationships of Sternoptychidae using a genome-scale dataset with ultraconserved elements (UCEs) and protein-coding gene fragments. This dataset is then combined with previously published morphological data to infer a total evidence hypothesis for the evolutionary relationships among deep-sea hatchetfishes. The phylogenetic analyses infer the Sternoptychidae to be a monophyletic family, although these results differ from previous phylogenetic studies regarding the monophyly of the subfamilies ‘Maurolicinae’ and Sternoptychinae. The ‘Maurolicinae’ consists of seven slender-bodied genera (Araiophos, Argyripnus, Danaphos, Maurolicus, Sonoda, Thorophos, Valenciennellus) and Sternoptychinae includes three deep-bodied genera (Argyropelecus, Polyipnus, Sternoptyx). The hypothesis of relationships presented herein for the family infers a polyphyletic ‘Maurolicinae’ with Maurolicus inferred to be nested within the subfamily Sternoptychinae. To investigate the evolution of body shape in the deep-sea hatchetfishes, patterns of body-shape were quantified in 684 digitized specimens using a geometric morphometric approach with seven homologous landmarks and 106 semi-landmarks. The relative warp analysis clustered species within genera together in relationship to their deep or slender body-shape. The geometric morphometric analysis provides continuous characters of body shape that allowed for a species-level ancestral character state reconstruction in combination with the total evidence phylogeny. The results presented herein infer a slender-bodied common ancestor for the family Sternoptychidae with three independent transitions to deeper bodies.
May, Zachary A., "Evolutionary Relationships and Evolution of Body Shape of the Deep-Sea Hatchetfishes (Stomiiformes: Sternoptychidae)." (2019). Culminating Projects in Biology. 43.
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