The Structure of Genetic Diversity in Eelgrass (Zostera marina L.) along the North Pacific and Bering Sea Coasts of Alaska.
Eelgrass (Zostera marina) populations occupying coastal waters of Alaska are separated by a peninsula and island archipelago into two Large Marine Ecosystems (LMEs). From populations in both LMEs, we characterize genetic diversity, population structure, and polarity in gene flow using nuclear microsatellite fragment and chloroplast and nuclear sequence data. An inverse relationship between genetic diversity and latitude was observed (heterozygosity: R2 = 0.738, P < 0.001; allelic richness: R2 = 0.327, P = 0.047), as was significant genetic partitioning across most sampling sites (θ = 0.302, P < 0.0001). Variance in allele frequency was significantly partitioned by region only in cases when a population geographically in the Gulf of Alaska LME (Kinzarof Lagoon) was instead included with populations in the Eastern Bering Sea LME (θp = 0.128-0.172; P < 0.003), suggesting gene flow between the two LMEs in this region. Gene flow among locales was rarely symmetrical, with notable exceptions generally following net coastal ocean current direction. Genetic data failed to support recent proposals that multiple Zostera species (i.e. Z. japonica and Z. angustifolia) are codistributed with Z. marina in Alaska. Comparative analyses also failed to support the hypothesis that eelgrass populations in the North Atlantic derived from eelgrass retained in northeastern Pacific Last Glacial Maximum refugia. These data suggest northeastern Pacific populations are derived from populations expanding northward from temperate populations following climate amelioration at the terminus of the last Pleistocene glaciation.
Alaska Science Center, U.S. Geological Survey, Anchorage, Alaska, United States of America.
Sandra L
SL
Talbot
Alaska Science Center, U.S. Geological Survey, Anchorage, Alaska, United States of America.
George K
GK
Sage
Alaska Science Center, U.S. Geological Survey, Anchorage, Alaska, United States of America.|Department of Biology, University of New Mexico, Albuquerque, New Mexico, United States of America.
Jolene R
JR
Rearick
Alaska Science Center, U.S. Geological Survey, Anchorage, Alaska, United States of America.
Meg C
MC
Fowler
Escuela de Ciencias de la Salud, Universidad Autónoma de Baja California, Ensenada, Baja California, Mexico.
Raquel
R
Muñiz-Salazar
Biological Sciences, Humboldt State University, Arcata, California, United States of America.
Bethany
B
Baibak
Friday Harbor Laboratories, University of Washington, Friday Harbor, Washington, United States of America.|Center for Marine and Environmental Studies, University of Virgin Islands, St. Thomas, Virgin Islands, United States of America.
Sandy
S
Wyllie-Echeverria
Instituto de Investigaciones Oceanológicas, Universidad Autónoma de Baja California, California, Mexico.
Alejandro
A
Cabello-Pasini
Alaska Science Center, U.S. Geological Survey, Anchorage, Alaska, United States of America.
David H
DH
Ward
D000413:Alaska; D014644:Genetic Variation; D018895:Microsatellite Repeats / Q000235:genetics; D010140:Pacific Ocean; D035962:Zosteraceae / Q000235:genetics*