Dear Colleagues, We are pleased to announce a new article published online today ahead of publication in a future print version of *Heredity.* The study investigates whether previously published genomic data conclusively support a scenario in which the ecotypes of killer whale found in the North Pacific diversified in sympatry, or whether there is a genomic signature consistent with a period of allopatry. Genome-wide SNP data suggest complex ancestry of sympatric North Pacific killer whale ecotypes AD Foote and PA Morin Three ecotypes of killer whale occur in partial sympatry in the North Pacific. Individuals assortatively mate within the same ecotype, resulting in correlated ecological and genetic differentiation. A key question is whether this pattern of evolutionary divergence is an example of incipient sympatric speciation from a single panmictic ancestral population, or whether sympatry could have resulted from multiple colonisations of the North Pacific and secondary contact between ecotypes. Here, we infer multilocus coalescent trees from 41000 nuclear single-nucleotide polymorphisms (SNPs) and find evidence of incomplete lineage sorting so that the genealogies of SNPs do not all conform to a single topology. To disentangle whether uncertainty in the phylogenetic inference of the relationships among ecotypes could also result from ancestral admixture events we reconstructed the relationship among the ecotypes as an admixture graph and estimated f4-statistics using TreeMix. The results were consistent with episodes of admixture between two of the North Pacific ecotypes and the two outgroups (populations from the Southern Ocean and the North Atlantic). Gene flow may have occurred via unsampled ‘ghost’ populations rather than directly between the populations sampled here. Our results indicate that because of ancestral admixture events and incomplete lineage sorting, a single bifurcating tree does not fully describe the relationship among these populations. The data are therefore most consistent with the genomic variation among North Pacific killer whale ecotypes resulting from multiple colonisation events, and secondary contact may have facilitated evolutionary divergence. Thus, the present-day populations of North Pacific killer whale ecotypes have a complex ancestry, confounding the tree-based inference of ancestral geography. Heredity (2016) doi:10.1038/hdy.2016.54 The full text can be accessed via this link: http://www.nature.com/hdy/journal/vaop/ncurrent/full/hdy201654a.html Andy Foote and Phil Morin Andrew Foote Institute of Ecology and Evolution University of Bern Baltzerstrasse 6 CH-3012 Bern Switzerland +41 31 631 45 49 andrew.foote@iee.unibe.ch https://www.researchgate.net/profile/Andy_Foote