Advanced Topics in Conservation Genetics Webinar Series

Advanced Topics in Conservation Genetics

These webinars provide biologist and managers with the latest techniques in conservation genetics.

This webinar series is for educational purposes only. The opinions, ideas or data presented in this webinar series do not represent FWS policy or constitute endorsement by FWS. Some of the materials and images may be protected by copyright or may have been licenses to us by a third party and are restricted in their use.  Mention of any product names, companies, Web links, textbooks, or other references does not imply Federal endorsement.


Date: Tuesday, January 20th, 2015
Time: 2:00-3:00 PM EST

The Influence of Variable Age at Maturity on Genetic Structure in Coho Salmon

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Archive: If you are unable to attend this webinar, it will be recorded and posted to the Advanced Topics in Conservation Genetics Webinar Series Archive approximately 1-2 weeks after the presentation.

Dr. Christian Smith, USFWS.

Description: Most coho salmon (Oncorhynchus kisutch) in Washington State spawn at three years of age, creating the potential for three temporal populations or “broodlines” at each spawning site. This is generally prevented by a portion of males in each site that mature and reproduce as two-year olds, resulting in population structure in which the geographic component is stronger than the freshwater museltemporal component. The Quilcene National Fish Hatchery selected against latest returning coho salmon by excluding all but the earliest returning fish from its broodstock for an unknown number of generations, and restricted gene flow among broodlines by excluding two-year old males for 27 generations. The resulting hatchery population exhibited three distinct broodlines which returned in alternating years: an “early” broodline which arrived one month before the wild fish; a “late” broodline which arrived at the same time as the wild fish; and a “middle” broodline which arrived in between these two. We evaluated temporal and geographic components of population genetic structure in coho salmon from the Quilcene National Fish Hatchery and nine other sites from Puget Sound and the Strait of Juan de Fuca using 10 microsatellite loci. Genetic diversity at the Quilcene National Fish Hatchery was lowest in the early broodline and highest in the late broodline. Divergence among broodlines was generally much lower than divergence among sites, rendering the term broodline irrelevant for most sites. Divergence among broodlines at the Quilcene National Fish Hatchery, however, was greater than that observed at any other site, and was also greater than that observed between any of the sites. This apparent reversal of the relative magnitudes of temporal and geographic components for this species emphasizes the importance of variable age-at-maturity in shaping population genetic structure.


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Marilyn Williams, Training Technician, Conservation Science and Policy Branch, National Conservation Training Center at 304-876-7940; e-mail


Matthew Patterson, Course Leader, Conservation Science and Policy Branch, National Conservation Training Center at 304-876-7473; e-mail