Out crosses between seasonally different segments of a Pacific salmon population reveal local adaptation

• Published in: Environmental biology of fishes 2017-11, Vol.100 (11), p.1469-1481
• Main Authors: Echave, Jesse D., Manhard, Christopher V., Smoker, William W., Adkison, Milo D., Gharrett, Anthony J.
• Format: Article
• Language: English
• Subjects: Adaptation; Additives; Animal embryos; Animal Systematics/Taxonomy/Biogeography; Barriers; Biomedical and Life Sciences; Climate change; Components; Environment; Fish; Fish populations; Fitness; Freshwater & Marine Ecology; Freshwater fishes; Genetic diversity; Incubation period; Interactions; Life Sciences; Mental depression; Natural selection; Nature Conservation; Oncorhynchus gorbuscha; Population; Population genetics; Populations; Reproductive fitness; Salmon; Seasons; Segments; Spawning; Subpopulations; Temperature; Temperature effects; Zoology
• ISSN: 0378-1909; 1573-5133
• DOI: 10.1007/s10641-017-0657-3

In salmon populations, local adaptation to seasonally varying incubation temperature is characterized by temperature-adjusted development times [measured in degree days – accumulated temperature units (ATUs)] that differ between control and F 1 hybrid crosses that were made between temporally separated population segments, a contrast not expected in a panmictic population. We examined adaptation of embryo development time to seasonally cooling temperature in a population of pink salmon by estimating genetic components of variation in control and hybrid F 1 crosses made between members of early- and late-spawning subpopulations, and replicated our observations in independent odd- and even-year brood lines. In each brood line, both sire and dam components of variation of development time were significant and accounted for a substantially larger portion of variation than their interactions, which suggested that natural selection has acted primarily on additive genetic variation. The implications of these results are that (1) spatially or temporally proximate salmon populations may be structured by distinct adaptations; (2) artificial relaxation of local geneflow barriers may lead to depression of fitness; and (3) populations of salmon genetically structured by local adaptation may carry variation that enhances their persistence during rapid climate change.