title: Effectiveness of managed gene flow in reducing genetic divergence associated with captive breeding.
abstract: Captive breeding has the potential to rebuild depressed populations. However, associated genetic changes may decrease restoration success and negatively affect the adaptive potential of the entire population. Thus, approaches that minimize genetic risks should be tested in a comparative framework over multiple generations. Genetic diversity in two captive-reared lines of a species of conservation interest, Chinook salmon (Oncorhynchus tshawytscha), was surveyed across three generations using genome-wide approaches. Genetic divergence from the source population was minimal in an integrated line, which implemented managed gene flow by using only naturally-born adults as captive broodstock, but significant in a segregated line, which bred only captive-origin individuals. Estimates of effective number of breeders revealed that the rapid divergence observed in the latter was largely attributable to genetic drift. Three independent tests for signatures of adaptive divergence also identified temporal change within the segregated line, possibly indicating domestication selection. The results empirically demonstrate that using managed gene flow for propagating a captive-reared population reduces genetic divergence over the short term compared to one that relies solely on captive-origin parents. These findings complement existing studies of captive breeding, which typically focus on a single management strategy and examine the fitness of one or two generations.
authors.affiliation: School of Aquatic and Fishery Sciences, University of Washington Seattle, WA, USA.
authors.forename: Charles D
authors.initials: CD
authors.lastname: Waters
authors.affiliation: Northwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration Seattle, WA, USA.
authors.forename: Jeffrey J
authors.initials: JJ
authors.lastname: Hard
authors.affiliation: School of Aquatic and Fishery Sciences, University of Washington Seattle, WA, USA.
authors.forename: Marine S O
authors.initials: MS
authors.lastname: Brieuc
authors.affiliation: Yakama Nation Fisheries Toppenish, WA, USA.
authors.forename: David E
authors.initials: DE
authors.lastname: Fast
authors.affiliation: Washington Department of Fish and Wildlife Olympia, WA, USA.
authors.forename: Kenneth I
authors.initials: KI
authors.lastname: Warheit
authors.affiliation: Northwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration Seattle, WA, USA.
authors.forename: Robin S
authors.initials: RS
authors.lastname: Waples
authors.affiliation: Oncorh Consulting Olympia, WA, USA.
authors.forename: Curtis M
authors.initials: CM
authors.lastname: Knudsen
authors.affiliation: Yakama Nation Fisheries Toppenish, WA, USA.
authors.forename: William J
authors.initials: WJ
authors.lastname: Bosch
authors.affiliation: School of Aquatic and Fishery Sciences, University of Washington Seattle, WA, USA.
authors.forename: Kerry A
authors.initials: KA
authors.lastname: Naish
keywords: captive breeding; domestication selection; genome-wide survey; managed gene flow; supportive breeding