The genomic history of killer whale ecotypes

Andy Foote
Bangor University, Bangor, UK - footead@gmail.com

Seminar in English

Killer whales are globally distributed and in at high latitudes have diversified into reproductively and socially isolated, specialized ecotypes. Analysing population genomic data from killer whale ecotypes, which we estimate have globally radiated within less than 250,000 years, we show that genetic structuring including the segregation of potentially functional alleles is associated with socially inherited ecological niche. Reconstruction of ancestral demographic history revealed bottlenecks during founder events, likely promoting ecological divergence and genetic drift resulting in a wide range of genome-wide differentiation between pairs of allopatric and sympatric ecotypes. Functional enrichment analyses provided evidence for regional genomic divergence associated with habitat, dietary preferences and post-zygotic reproductive isolation. Our findings are consistent with expansion of small founder groups into novel niches by an initial plastic behavioural response, perpetuated by social learning imposing an altered natural selection regime. RAD-seq data and on-going analysis into a new global genome resequencing dataset, allow the exploration of whether ecotypic divergence is an example of incipient sympatric speciation, or whether sympatry could have resulted from multiple colonisations and secondary contact between ecotypes.

Recent publications:

Foote AD, Morin PA (2016) Genome-wide SNP data suggests complex ancestry of sympatric North Pacific killer whale ecotypes. Heredity 117, 316-325

Foote AD et al. (2016) Genome culture coevolution promotes rapid divergence of killer whale ecotypes. Nature Communications 7:11693

Foote AD, et al. (2015) Convergent evolution of the genomes of marine mammals. Nature Genetics 47, 272-275