Wild pedigrees inform mutation rates and historic abundance in baleen whales

<p>Phylogeny-based estimates suggesting a low germline mutation rate (<em>μ</em>) in baleen whales have influenced research ranging from assessments of whaling impacts to evolutionary cancer biology. We estimated <em>μ</em> 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 <em>μ</em> reduces previous genetic–based estimates of pre-exploitation whale abundance by 86% and suggests that <em>μ</em> cannot explain low cancer rates in gigantic mammals. Our study shows that it is feasible to estimate <em>μ</em> directly from pedigrees in natural populations, with wide-ranging implications for ecological and evolutionary research.</p>