Phylogeography of the tidewater goby, Eucyclogobius newberryi (Teleostei, gobiidae), in coastal California

The tidewater goby, Eucyclobius newberryi, inhabits discrete, seasonally cl osed estuaries and lagoons along approximately 1500 km of California coastl ine. This species is euryhaline but has no explicit marine stage, yet ;popu lation extirpation and recolonization data suggest tidewater gobies dispers e intermittently via the sea. Analyses of mitochondrial control region and cytochrome b sequences demonstrate a deep evolutionary bifurcation in the v icinity of Los Angeles that separates southern California populations from all more northerly populations. Shallower phylogeographic breaks, in the vi cinities of Seacliff, Point Buchon, Big Sur, and Point Arena segregate the northerly populations into five groups in three geographic clusters: the Po int Conception and Ventura groups between Los Angeles and Point Buchon, a l one Estero Bay group from central California, and San Francisco and Cape Me ndocino groups from northern California. The phylogenetic relationships bet ween and patterns of molecular diversity within the six groups are consiste nt with repeated, and sometimes rapid, northward and southward range expans ions out of central California caused by Quaternary climate change. Plio-Pl eistocene tectonism, Quaternary coastal geography and hydrography, and hist orical human activities probably also influenced the modern geographic and genetic structure of E. newberryi. The phylogeography of E. newberryi is co ncordant with phylogeographic patterns in several other coastal California taxa, suggesting common extrinsic factors have had similar effects on diffe rent species. However, there is no evidence of a phylogeographic break coin cident with a biogeographic boundary at Point Conception.