Upside-down and backwards: Molecular evolution of the longjaw mudsucker, Gillichthy mirabilis, in the Sea of Cortez

Gillichthys mirabilis is believed to be a disjunct population. Part of that population was believed to be isolated during formation of the Sea of Cortez. The paedomorphic daughter species of G. mirabilis, Gillichthys seta, is endemic to the northern Sea of Cortez. An isolated Cortez population of G. mirabilis allows study of a natural founder event. Theory predicts that Cortez G. mirabilis should have lower genetic diversity than the Pacific population, and G. seta should have even less genetic diversity. Four hundred nine base pairs of the mtDNA control region of Pacific and Cortez G. mirabilis and G. seta were sequenced and analyzed to determine singleton fraction and nucleotide and haplotype diversities. Those indices were highest in G. seta followed by Cortez and finally Pacific G. mirabilis. Statistical parsimony indicates that Pacific G. mirabilis is the parent of the Cortez population. Higher genetic diversities in Cortez populations are attributable to higher metabolism.