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A complex phenotype in salmon controlled by a simple change in migratory timing.
Neil F Thompson1,2,3, Eric C Anderson4,3,5, Anthony J Clemento2,3
1Department of Ocean Sciences, University of California, Santa Cruz, Santa Cruz, CA 95064, USA.
Science (New York, N.Y.)
|October 30, 2020
Summary
Chinook salmon ecotypes are not complex, polygenic traits. A single genomic region controls migration timing, simplifying conservation efforts for this iconic fish.
Area of Science:
- Genomics
- Evolutionary Biology
- Conservation Genetics
Background:
- Salmon ecotype differentiation is typically considered complex and polygenic.
- Seasonal life history patterns are commonly used to define salmon ecotypes.
- Traits like adiposity and sexual maturity are often central to ecotype definitions.
Purpose of the Study:
- To investigate the genetic basis of Chinook salmon ecotype differentiation.
- To determine if complex phenotypes result from single or multiple genetic factors.
- To identify genetic regions associated with key ecotype-defining traits.
Main Methods:
- Whole-genome sequencing of Chinook salmon.
- Analysis of tribal fishery samples.
- Association mapping to identify genomic regions linked to phenotypic traits.
Main Results:
- A single, small genomic region is strongly associated with spawning migration timing.
- This region is not associated with adiposity or sexual maturity.
- Distinct migration timings do not preclude interbreeding between ecotypes.
Conclusions:
- Chinook salmon ecotype differentiation is driven by a simple, ancient polymorphism in a single gene region.
- Complex migratory phenotypes can arise from single genetic loci.
- This finding simplifies conservation and restoration strategies for Chinook salmon.
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