Thesis

Genetic variation among kelp bass (paralabrax clathratus) from seven locations throughout their natural range

Paralabrax clathratus, commonly known as the kelp bass, is an important sportfish to the Southern California angler, ranking among the top sportfish on commercial passenger fishing vessels since the 1950's. They commonly occur in a patchy distribution from Monterey Bay, CA to central Baja California, Mexico, preferring a habitat associated with structure. They are broadcast spawners and have the potential for high levels of gene flow during the 28-30 day pelagic larval stage. The purpose of this investigation was to determine the extent of genetic variation of the kelp bass at various locations throughout their range. Seven populations were examined for genetic variation and population subdivision using two variable molecular markers. Restriction fragment length polymorphism (RFLP) of the internal transcribed spacer regions (ITS) of the nuclear ribosomal DNA repeat unit revealed no genetic variation or geographic subdivision. Although direct sequence analysis of the 5' portion of the mitochondrial DNA revealed a high level of genetic variation , no geographic subdivision was detected based on neighbor joining, maximum parsimony, and analysis of molecular variance (AMOVA). These results suggest that a high level of gene flow exist among locations, most likely due to the dispersal of pelagic larvae via prevailing currents, episodic events, and adult movements.

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