Genetic pedigree analyses of Arctic grayling offspring produced to initiate the Michigan reintroduction program

Abstract

Measures of genetic diversity among individuals within and between broodstock year classes of Arctic Grayling (Thymallus arcticus) were quantified as part of a large inter-disciplinary effort to repatriate the species into Michigan fluvial habitats. Genetic pedigree analysis of 200 juveniles from each of the 2019 and 2021 year classes indicated that 205 and 218 adults from a natural stream population in central Alaska contributed to offspring genotyped. Because broodstock sampling occurred in the same stream location each year and adults were not marked, 22.4 % of successful adults were estimated to have contributed to offspring genotyped in both years, indicating that the local adult population was philopatric to the spawning site and of moderate size. Measures of genetic diversity including heterozygosity and allelic diversity were high, while inbreeding coefficients (F_IS), and estimates of inter-individual relatedness (R_XY) of offspring genotyped within and between year classes were low. Collectively, results indicate that crosses conducted among adults to establish broodstock year classes had achieved restoration program goals of creating a genetically diverse domestic broodstock to use for future repatriation efforts.