Cranial shape correlates with diet specialization in northeast Pacific killer whale (Orcinus orca) ecotypes.
Resident, transient (Bigg’s), and offshore killer whales (Orcinus orca) live in sympatric and parapatric ranges in the northeast Pacific Ocean. These ecotypes have different vocal repertoires (Ford and Fisher, 1982; Ford, 1991; Yurk, 2002), echolocation use (Barrett-Lennard et al., 1996), foraging s...
Main Author: | |
---|---|
Format: | Thesis |
Language: | English |
Published: |
University of British Columbia
2016
|
Subjects: | |
Online Access: | http://hdl.handle.net/2429/59077 |
id |
ftunivbritcolcir:oai:circle.library.ubc.ca:2429/59077 |
---|---|
record_format |
openpolar |
spelling |
ftunivbritcolcir:oai:circle.library.ubc.ca:2429/59077 2023-05-15T17:03:41+02:00 Cranial shape correlates with diet specialization in northeast Pacific killer whale (Orcinus orca) ecotypes. Fung, Charissa W. 2016 http://hdl.handle.net/2429/59077 eng eng University of British Columbia Attribution-NonCommercial-NoDerivatives 4.0 International http://creativecommons.org/licenses/by-nc-nd/4.0/ CC-BY-NC-ND Text Thesis/Dissertation 2016 ftunivbritcolcir 2019-10-15T18:21:13Z Resident, transient (Bigg’s), and offshore killer whales (Orcinus orca) live in sympatric and parapatric ranges in the northeast Pacific Ocean. These ecotypes have different vocal repertoires (Ford and Fisher, 1982; Ford, 1991; Yurk, 2002), echolocation use (Barrett-Lennard et al., 1996), foraging strategies (Bigg et al., 1987; Ford et al., 1998; Baird et al., 1992; Deecke et al., 2002; Ford et al., 2011), and sociobiology (Ford and Fisher, 1982; Bigg et al., 1987; Deecke et al., 2000; Baird and Whitehead, 2000; Riesch et al., 2012). Genetic studies corroborate the behavioural evidence that the resident and transient (Bigg’s) populations are reproductively isolated despite the absence of any geographic or temporal barrier (Stevens et al., 1989; Barrett-Lennard, 2000; Hoelzel and Dover, 1991; Morin et al., 2010). The behavioural segregation between the sympatric ecotypes is apparently maintained by cultural mechanisms alone, which is extremely unusual among non-human mammalian species (Barrett-Lennard, 2000; Riesch et al., 2012). These ecotypes also exhibit dramatic resource polymorphisms: resident killer whales feed exclusively on fish, transient (Bigg’s) killer whales primarily hunt marine mammals (Bigg, 1982; Baird et al., 1992, Ford et al., 1998) and offshore killer whales are thought to feed on fishes including Pacific sleeper shark (Somniosus pacificus) (Ford et al., 2011). We do not know if cranial features related to capturing and processing prey have evolved to reflect the dramatic dietary specializations observed in these three ecotypes. The goal of this research was to determine whether there has been divergence of cranial morphology among the three ecotypes. To this end, I measured and compared cranial shape using traditional and geometric morphometrics techniques. I found that transient (Bigg’s) killer whales that bite and tear apart large mammals have more robust cranial skeletons than the piscivorous resident and offshore killer whales that handle smaller prey items. I found that resident and transient (Bigg’s) killer whales are distinguishable based on skull width, rostral width, and mandibular shape, and that offshore killer whales have a more variable morphology that precludes identification based on cranial shape alone. Science, Faculty of Zoology, Department of Graduate Thesis Killer Whale Orca Orcinus orca Killer whale University of British Columbia: cIRcle - UBC's Information Repository Barrett ENVELOPE(-126.773,-126.773,54.428,54.428) Dover ENVELOPE(-55.753,-55.753,-83.777,-83.777) Pacific |
institution |
Open Polar |
collection |
University of British Columbia: cIRcle - UBC's Information Repository |
op_collection_id |
ftunivbritcolcir |
language |
English |
description |
Resident, transient (Bigg’s), and offshore killer whales (Orcinus orca) live in sympatric and parapatric ranges in the northeast Pacific Ocean. These ecotypes have different vocal repertoires (Ford and Fisher, 1982; Ford, 1991; Yurk, 2002), echolocation use (Barrett-Lennard et al., 1996), foraging strategies (Bigg et al., 1987; Ford et al., 1998; Baird et al., 1992; Deecke et al., 2002; Ford et al., 2011), and sociobiology (Ford and Fisher, 1982; Bigg et al., 1987; Deecke et al., 2000; Baird and Whitehead, 2000; Riesch et al., 2012). Genetic studies corroborate the behavioural evidence that the resident and transient (Bigg’s) populations are reproductively isolated despite the absence of any geographic or temporal barrier (Stevens et al., 1989; Barrett-Lennard, 2000; Hoelzel and Dover, 1991; Morin et al., 2010). The behavioural segregation between the sympatric ecotypes is apparently maintained by cultural mechanisms alone, which is extremely unusual among non-human mammalian species (Barrett-Lennard, 2000; Riesch et al., 2012). These ecotypes also exhibit dramatic resource polymorphisms: resident killer whales feed exclusively on fish, transient (Bigg’s) killer whales primarily hunt marine mammals (Bigg, 1982; Baird et al., 1992, Ford et al., 1998) and offshore killer whales are thought to feed on fishes including Pacific sleeper shark (Somniosus pacificus) (Ford et al., 2011). We do not know if cranial features related to capturing and processing prey have evolved to reflect the dramatic dietary specializations observed in these three ecotypes. The goal of this research was to determine whether there has been divergence of cranial morphology among the three ecotypes. To this end, I measured and compared cranial shape using traditional and geometric morphometrics techniques. I found that transient (Bigg’s) killer whales that bite and tear apart large mammals have more robust cranial skeletons than the piscivorous resident and offshore killer whales that handle smaller prey items. I found that resident and transient (Bigg’s) killer whales are distinguishable based on skull width, rostral width, and mandibular shape, and that offshore killer whales have a more variable morphology that precludes identification based on cranial shape alone. Science, Faculty of Zoology, Department of Graduate |
format |
Thesis |
author |
Fung, Charissa W. |
spellingShingle |
Fung, Charissa W. Cranial shape correlates with diet specialization in northeast Pacific killer whale (Orcinus orca) ecotypes. |
author_facet |
Fung, Charissa W. |
author_sort |
Fung, Charissa W. |
title |
Cranial shape correlates with diet specialization in northeast Pacific killer whale (Orcinus orca) ecotypes. |
title_short |
Cranial shape correlates with diet specialization in northeast Pacific killer whale (Orcinus orca) ecotypes. |
title_full |
Cranial shape correlates with diet specialization in northeast Pacific killer whale (Orcinus orca) ecotypes. |
title_fullStr |
Cranial shape correlates with diet specialization in northeast Pacific killer whale (Orcinus orca) ecotypes. |
title_full_unstemmed |
Cranial shape correlates with diet specialization in northeast Pacific killer whale (Orcinus orca) ecotypes. |
title_sort |
cranial shape correlates with diet specialization in northeast pacific killer whale (orcinus orca) ecotypes. |
publisher |
University of British Columbia |
publishDate |
2016 |
url |
http://hdl.handle.net/2429/59077 |
long_lat |
ENVELOPE(-126.773,-126.773,54.428,54.428) ENVELOPE(-55.753,-55.753,-83.777,-83.777) |
geographic |
Barrett Dover Pacific |
geographic_facet |
Barrett Dover Pacific |
genre |
Killer Whale Orca Orcinus orca Killer whale |
genre_facet |
Killer Whale Orca Orcinus orca Killer whale |
op_rights |
Attribution-NonCommercial-NoDerivatives 4.0 International http://creativecommons.org/licenses/by-nc-nd/4.0/ |
op_rightsnorm |
CC-BY-NC-ND |
_version_ |
1766057592680873984 |