Amino acid δ(15)N differences consistent with killer whale ecotypes in the Arctic and Northwest Atlantic

Ecotypes are groups within a species with different ecological adaptations than their conspecifics. Eastern North Pacific (ENP) killer whale (Orcinus orca) ecotypes differ in their diet, behavior, and morphology, but the same is not known for this species in the eastern Canadian Arctic (ECA) and Nor...

Full description

Bibliographic Details
Published in:PLOS ONE
Main Authors: Matthews, Cory J. D., Lawson, Jack W., Ferguson, Steven H.
Format: Text
Language:English
Published: Public Library of Science 2021
Subjects:
Research Article
Arctic
Pacific
Killer Whale
Northwest Atlantic
Orca
Orcinus orca
Killer whale
Online Access:http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8018630/
http://www.ncbi.nlm.nih.gov/pubmed/33798257
https://doi.org/10.1371/journal.pone.0249641
Description
Summary:Ecotypes are groups within a species with different ecological adaptations than their conspecifics. Eastern North Pacific (ENP) killer whale (Orcinus orca) ecotypes differ in their diet, behavior, and morphology, but the same is not known for this species in the eastern Canadian Arctic (ECA) and Northwest Atlantic (NWA). Using compound-specific stable isotope analysis (CSIA) of amino acids (AAs), we compared δ(15)N patterns of the primary trophic and source AA pair, glutamic acid/glutamine (Glx) and phenylalanine (Phe), in dentine collagen of (1) sympatric ENP killer whale ecotypes with well-characterized diet differences and (2) ECA/NWA killer whales with unknown diets. δ(15)N(Glx-Phe) was significantly higher in the ENP fish-eating (FE) than mammal-eating (ME) ecotype (19.2 ± 0.4‰ vs. 13.5 ± 0.7‰, respectively). Similar bimodal variation in δ(15)N(Glx-Phe) indicated analogous dietary divisions among ECA/NWA killer whales, with two killer whales having higher δ(15)N(Glx-Phe) (16.5 ± 0.0‰) than the others (13.5 ± 0.6‰). Inferences of dietary divisions between these killer whales were supported by parallel differences in threonine δ(15)N (–33.5 ± 1.6‰ and –40.4 ± 1.1‰, respectively), given the negative correlation between δ(15)N(Thr) and TP across a range of marine consumers. CSIA-AA results for ECA/NWA whales, coupled with differences in tooth wear (a correlate for diet), are consistent with ecotype characteristics reported in ENP and other killer whale populations, thus adding to documented ecological divergence in this species worldwide.

Similar Items