Wild pedigrees inform mutation rates and historic abundance in baleen whales

Phylogeny-based estimates suggesting a low germline mutation rate (μ) in baleen whales have influenced research ranging from assessments of whaling impacts to evolutionary cancer biology. We estimated μ directly from pedigrees in four baleen whale species for both the mitochondrial control region and nuclear genome. The results suggest values higher than those obtained through phylogeny-based estimates and similar to pedigree-based values for primates and toothed whales. Applying our estimate of μ reduces previous genetic-based estimates of preexploitation whale abundance by 86% and suggests that μ cannot explain low cancer rates in gigantic mammals. Our study shows that it is feasible to estimate μ directly from pedigrees in natural populations, with wide-ranging implications for ecological and evolutionary research. The rate of genetic mutation that occurs across generations is regularly used to estimate a wide array of measures, including past population sizes. It also varies depending on a suite of considerations, including generation time and body size, and is notoriously difficult to estimate in wild animal species. Suárez-Menéndez et al. used a pedigree approach in four wild baleen whale species, producing a mutation rate different from that estimated using a phylogenetic approach (see the Perspective by Hoelzel and Lynch). The new rate is faster than previously estimated for these large animals, being more consistent with primates and other smaller species with similar generation times. —Sacha Vignieri Direct estimates of mutation rates in four baleen whale species have wide-ranging evolutionary and conservation implications.