Date Awarded


Document Type


Degree Name

Doctor of Philosophy (Ph.D.)


Virginia Institute of Marine Science


John A. Musick


Phylogenetic and historical biogeographic hypotheses were explored for three groups of teleost fishes that are hypothesized to share a common biogeographic track. Distributed across the eastern Pacific/eastern Atlantic (EP/EA) biogeographic track of Rosen (1975) are the Scomberomorus regalis (Scombridae), Strongylura marina (Belonidae) and Hyporhamphus unifasciatus (Hemiramphidae) species groups comprised of one eastern Atlantic; three, three and four western Atlantic; and two, two and four eastern Pacific species, respectively, for each group. In addition, two species in the Strongylura marina and Hyporhamphus unifasciatus groups, have invaded freshwater drainages of Central and South America. Each of the three species groups were found to be monophyletic using on average 3000 base pairs (bps) of nucleotide sequence. Genes sequenced included: the entire ATP synthase 8 (ATPase 8; 169 bp) and 6 (ATPase 6; 684 bp), NADH ubiquione oxidoreductase subunit 2 (ND2; 1047 bp), and partial cytochrome b (cyt b; 800 bp) mtDNA protein coding genes; partial 12S (12S; 429 bp) and 16S (16S; 576 bp) ribosomal mtDNA genes; and portions of the nuclear encoded aldolase exon 5/intron 5 (ALD; &\sim&400bp) and creatine kinase b introns and exons 2 and 3 (CK; &\sim&1042 bp). The analysis of multiple genes permitted an evaluation of their phylogenetic signal and usefulness in biogeographic reconstructions. Mitochondrial protein-coding genes resulted in well-supported resolution of sister species relationships, while the nuclear-encoded genes helped resolve basal relationships. However, contrary to expectations, the mtDNA ribosomal genes did not perform as well. Additionally, in Scomberomorus a morphology-based phylogeny was included in the analysis. In general phylogenetic hypotheses inferred for each species group were consistent with expectations of the EP/EA generalized biogeographic track. The results for each species group indicated a basal position for the eastern Atlantic taxa S. tritor, St. senegalensis and Hy. picarti, with closest relationships being either transisthmian (geminate) or, within the eastern Pacific or western Atlantic, for the derived New World taxa. Vicariant and dispersal hypotheses, consistent with paleogeological and paleoceanographic evidence, and life history and dispersal abilities are offered to explain the biogeographic histories of.



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