Genetic divergence in the tribe Electronini (Myctophidae)

To reveal evolutionary relationships and the rate of divergence of lanternfishes in the tribe Electronini (Myctophidae), analysis of sequence of cox 1 mtDNA fragment in three genera (12 species) of the tribe and in a closely related genus Myctophum (9 species) was performed. The results support the tribe monophyly; however, the divergence within it appeared to be not profound: genetic distances between genera and subgenera are smaller than between species within Myctophum and other genera of myctophids. In subgenera of Protomyctophum, species formation has obviously not completed since interspecies distances in them (0.5–4.7%) are comparable to estimates of intraspecific variation in other lanternfishes. Minimal genetic differences were found between species P. (Hierops) arcticum and P. (H.) subparallelum, whose ranges at the present time are isolated in the northern and southern hemispheres. After calibration of the molecular clock, the time of isolation of these two species can be dated to the Middle Pleistocene. Weak tribe diversification indicates its evolutionary youth, which can be related to the absence of efficient hydrographic barriers for isolation. The data obtained do not permit to consider tribe members as the most primitive in the family Myctophidae.