Molecular phylogeny and stripe pattern evolution in the cardinalfish genus Apogon

Area of Science:

• Marine Biology
• Ichthyology
• Evolutionary Biology
• Phylogenetics

Background:

• Cardinalfishes (family Apogonidae) are abundant and diverse in coral reefs, with the genus Apogon being particularly speciose.
• The genus Apogon is divided into 10 subgenera, with Ostorhinchus containing over 70% of the species, many characterized by body stripe patterns.

Purpose of the Study:

• To investigate the phylogenetic relationships within the Apogon genus, focusing on the subgenus Ostorhinchus.
• To clarify the evolutionary history and taxonomic status of cardinalfish species, particularly those within Ostorhinchus.

Main Methods:

• Phylogenetic analysis using mitochondrially encoded 12S and 16S ribosomal RNA genes and the intervening tRNA(Val) gene.
• Inclusion of 32 species from the subgenus Ostorhinchus and 11 species from four other Apogon subgenera.
• Utilized two species from the related genus Fowleria as outgroups for phylogenetic reconstruction.

Main Results:

• The subgenus Ostorhinchus was found to be polyphyletic, comprising at least three distinct evolutionary lineages (Ostorhinchus I, II, and III).
• Ostorhinchus I is sister to the subgenus Zoramia, while Ostorhinchus II and III correspond to species with horizontal and vertical body stripes, respectively.
• Molecular clock calibration suggests that fundamental stripe patterns in cardinalfish evolved over 20 million years ago, followed by diversification.

Conclusions:

• The traditional classification of Ostorhinchus does not reflect its evolutionary history, necessitating taxonomic revision.
• The study provides insights into the early evolution of body patterns in cardinalfishes, highlighting the antiquity of basic stripe development.