[MARMAM] New publication on the genetics of Icelandic killer whales: Killer whales (Orcinus orca) in Iceland show weak genetic structure among diverse isotopic signatures and observed movement patterns

Sara Tavares saratavares19 at gmail.com
Thu Nov 15 16:51:11 PST 2018

Dear colleagues,

My co-authors and I are pleased to announce that the following paper has
been published online:

*Killer whales (Orcinus orca) in Iceland show weak genetic structure among
diverse isotopic signatures and observed movement patterns*

Sara B. Tavares; Filipa I.P. Samarra; Sonia Pascoal; Jeff A. Graves;
Patrick J.O. Miller
Ecology and Evolution
Article DOI: 10.1002/ece3.4646


Local adaption through ecological niche specialization can lead to genetic
structure between and within populations. In the Northeast Pacific, killer
whales (*Orcinus orca*) of the same population have uniform specialized
diets that are non‐overlapping with other sympatric, genetically divergent,
and socially isolated killer whale ecotypes. However, killer whales in
Iceland show intrapopulation variation of isotopic niches and observed
movement patterns: some individuals appear to specialize on herring and
follow it year‐round while others feed upon herring only seasonally or
opportunistically. We investigated genetic differentiation among Icelandic
killer whales with different isotopic signatures and observed movement
patterns. This information is key for management and conservation purposes
but also for better understanding how niche specialization drives genetic
differentiation. Photo‐identified individuals (*N* = 61) were genotyped for
22 microsatellites and a 611 bp portion of the mitochondrial DNA (mtDNA)
control region. Photo‐identification of individuals allowed linkage of
genetic data to existing data on individual isotopic niche, observed
movement patterns, and social associations. Population subdivision into
three genetic units was supported by a discriminant analysis of principal
components (DAPC). Genetic clustering corresponded to the distribution of
isotopic signatures, mtDNA haplotypes, and observed movement patterns, but
genetic units were not socially segregated. Genetic differentiation was
weak (*F*ST < 0.1), suggesting ongoing gene flow or recent separation of
the genetic units. Our results show that killer whales in Iceland are not
as genetically differentiated, ecologically discrete, or socially isolated
as the Northeast Pacific prey‐specialized killer whales. If any process of
ecological divergence and niche specialization is taking place among killer
whales in Iceland, it is likely at a very early stage and has not led to
the patterns observed in the Northeast Pacific.

Available online at: https://rdcu.be/bbstM

Best regards,

Sara Tavares, PhD

NSERC Postdoctoral Fellow

Cetacean Research Program
Pacific Biological Station
Fisheries and Oceans Canada
3190 Hammond Bay Rd

Nanaimo, BC V9T 6N7

Email: saratavares19 at gmail.com
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