Phylogenetic relationships of tropical eastern Pacific snappers (Lutjanidae) inferred from mitochondrial DNA sequences

摘要

A total of 2,206 base pairs of coding sequences of mitochondrial DNA from nine of 10 lutjanine (Lutjanidae) species endemic to the eastern Pacific Ocean were used in a phylogenetic analysis to infer species relationships among lutjanines on either side of the Isthmus of Panama. Monotypic Hoplopagrus (guentherii) appears to be at the base of all lutjanines assayed to date and represents the first of five, eastward dispersal events of lutjanines from the Indo-Pacific to the Americas. Diversification of lutjanines in the Americas appears to have occurred primarily in the western Atlantic Ocean (Caribbean Sea) and been aided by an early Miocene eastward-flowing current and by more optimal lutjanine habitat in the warmer Caribbean waters. Five geminate species pairs in five, strongly supported clades were identified. In three, the trans-isthmian geminate species in the eastern Pacific belonged to clades in which basal and other members of the clade are endemic to the western Atlantic, suggesting that the ancestor to each species geminate pair dispersed westward into the eastern Pacific prior to closure of connections between the two oceans; the opposite occurred in one of the clades. The fifth clade contained only two species, one on either side of the Isthmus. Diversification in life-history and other traits in each geminate species pair appears to have been slight. Five lutjanine species possessing horizontal blue stripes (the blue-lined complex) and distributed from the western Indian Ocean to the eastern Pacific formed a strongly supported monophyletic clade. The lone blue-lined species in the eastern Pacific (Lutjanus viridis) could be conspecific with its highly dispersive sister species (Lutjanus kasmira) from the Indo-Pacific. The chronology of lutjanine diversification and closure of seawater exchange between the two oceans is briefly discussed.