Author contributions
A.A., N.R., and L.L. designed the study and led the collection of present-day samples. N.R. initiated and organized the collection of samples from the 1970s and 1980s, and those samples have been stored in a frozen tissue bank maintained by N.R. and L.L. at the Department of Zoology, Stockholm University. S.K. led the laboratory analyses. A.A. performed population genetics analyses, provided the first draft of the manuscript, and led the writing with all authors contributing to the final manuscript.