- Evolutionary history,
The spotted eagle ray (Aetobatus narinari), a large coral reef–associated batoid of conservation concern, is currently described as a single, circumglobally distributed species. However, geographic differences in its morphology and parasite diversity have raised unconfirmed suspicions that A. narinari may constitute a species complex. We used 1570 bp of mitochondrial and nuclear sequence data (cytochrome b, cytochrome coxidase subunit I, and internal transcribed spacer 2) to assess the validity of A. narinari as a single cosmopolitan species and infer its evolutionary history. Specimens from 4 major geographic regions were examined: the Central Atlantic, Eastern Pacific, Western Pacific, and Central Pacific. Phylogenies described 3 distinct, reciprocally monophyletic lineages with no genetic exchange among regions. Based on combined genealogical concordance and genetic distance criteria, we recommend that the Western/Central Pacific lineage be recognized as a distinct species from lineages in the Central Atlantic and Eastern Pacific. The latter 2 lineages, separated by the Isthmus of Panama, are proposed as subspecies. A basal position in phylogenetic analyses and statistical parsimony results support an Indo-West Pacific origin for the A. narinari species complex, with subsequent westerly dispersal around the southern tip of Africa into the Atlantic and then into the Eastern Pacific.
Available at: http://works.bepress.com/mahmood-shivji/101/