[MARMAM] new publication - killer whale genomics

Andy Foote footead at gmail.com
Wed Aug 3 07:24:32 PDT 2016

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:

Andy Foote and Phil Morin

Andrew Foote
Institute of Ecology and Evolution
University of Bern
Baltzerstrasse 6
CH-3012 Bern
+41 31 631 45 49
andrew.foote at iee.unibe.ch
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