30 October 2020
Vol 370, Issue 6516

About The Cover

Cover image expansion

COVER Chinook salmon swimming in the Rogue River, Oregon. Genome sequencing and analysis of tribal fishery catch in the Klamath River, California, show that salmon ecotypes in diverse populations result from a simple Mendelian polymorphism that affects seasonality of spawning migration. Physiological and reproductive differences long thought to distinguish ecotypes appear as a result of environmental effects from summer residence in different ecosystems. See pages 526 and 609.
Photo: Mark Conlin/Alamy Stock Photo