Kenneth S. Norris Rancho Marino Reserve

01 Dec, 01 AM - 31 Dec, 09 AM

This is a new project that aims to examine the genetic and phenotypic changes associated with the recent range expansion of the volcano barnacle Tetraclita rubescens. T. rubescens is endemic to the Pacific coast of Baja California and California. In 1980, it was reported to have a northern range limit at San Francisco (~38oN; Newman & Abbott 1980). In 1985 new observations described the northern limit as 39oN, and by 1995 T. rubescens had been found at Cape Mendocino (41oN; Connolly & Roughgarden 1998). A several-decades long warming trend in nearshore temperatures in California (Barry et al. 1995) could have facilitated expansion northward into areas that, up until 1980, were too cold for T. rubescens to survive. Alternative explanations for the northward expansion are that some T. rubescens may have acquired greater tolerance to cold facilitating their expansion north, some T. rubescens always had the adaptation but were for the first time delivered to northern sites by currents after 1980s (the delivery may be continual or episodic), the recent expansion may be just one episode of a normally fluctuating range boundary, or T. rubescens may always have existed at latitudes higher than 38oN before 1980 but was simply not observed due to low densities (Connolly & Roughgarden 1998). To distinguish among these hypotheses, we will use population genetic techniques to chronicle the history of recently detected populations of T. rubescens, and laboratory and field experiments to separate genetic from environmental components of phenotypic variation. Regardless of the outcome, this project will clarify the dynamics of populations near the northern limits of species distributions and either document the genetic repercussions of range expansion (if populations north of San Francisco were established post-1980), or provide information on factors that limit range expansion (if populations were always north of San Francisco, then they did not respond to the reported changes in sea surface temperature). This study will also have broader implications with respect to understanding some of the procesess that influence range expansions and the impacts of global climate change on the distribution and abundance of marine intertidal organisms.

Visit #8507 @Kenneth S. Norris Rancho Marino Reserve

Approved

Under Project # 5978 | Research

Genetic signals of range expansion: the case of the volcano barnacle, Tetraclita rubescens

research_scientist - University of California, Davis

Reservation Members(s)

Michael Dawson Dec 1 - 31, 2005 (31 days)
Michael Dawson Dec 1 - 31, 2005 (31 days)

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