Relatedness assignment
We calculated pairwise relatedness estimates using the R packageRelated using the filtered set of 5007 SNPs, as per . Pairwise relatedness across all pairs of individuals in our genetic dataset was estimated using Queller and Goodnight’s relatedness estimator . Although there are multiple relatedness estimates available, we selected to use Queller and Goodnight’s because it has previously been found to be the most accurate for this dataset in determining true pairwise relationships. Briefly, using simulated genotypes of known relationships, compared the accuracy of different estimates in correctly determining relationships (i.e. parent-offspring or half-sibs), finding that Queller and Goodnight’s estimate was the most accurate. Maternities were identified through genetic parentage analyses, or, rarely, through field observations. Materinity assignment was conducted using a reduced panel of more stringently filtered SNPs (N = 427 SNPs, MAF > 0.3, missingness < 1%, consistent marker scores for technical replicate assay pairs of >99%), linkage disequilibrium r2 < 0.4) in CERVUS 3.0.7 as per .