Determining sex of adult Pacific walruses from mandible measurements
Pacific walruses (Odobenus rosmarus divergens) play a vital role in Arctic marine ecosystems and the subsistence lifestyle of Alaska Native communities. Museum collections contain numerous archaeological and historic walrus specimens that have proven useful in a variety of studies; however, for many...
Published in: | Journal of Mammalogy |
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American Society of Mammalogists
2020
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Online Access: | https://doi.org/10.1093/jmammal/gyaa051 |
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ftbioone:10.1093/jmammal/gyaa051 2024-06-02T08:02:20+00:00 Determining sex of adult Pacific walruses from mandible measurements Nathan Taylor Casey T. Clark Nicole Misarti Lara Horstmann Nathan Taylor Casey T. Clark Nicole Misarti Lara Horstmann world 2020-06-20 text/HTML https://doi.org/10.1093/jmammal/gyaa051 en eng American Society of Mammalogists doi:10.1093/jmammal/gyaa051 All rights reserved. https://doi.org/10.1093/jmammal/gyaa051 Text 2020 ftbioone https://doi.org/10.1093/jmammal/gyaa051 2024-05-07T00:55:08Z Pacific walruses (Odobenus rosmarus divergens) play a vital role in Arctic marine ecosystems and the subsistence lifestyle of Alaska Native communities. Museum collections contain numerous archaeological and historic walrus specimens that have proven useful in a variety of studies; however, for many cases, the sex of these specimens is unknown. Sexes of adult (> 5 years determined by tooth aging) Atlantic walruses (Odobenus rosmarus rosmarus) have been accurately determined in previous studies using mandible measurements. We tested the validity of this approach for Pacific walruses, and used full fusion of the mandibular symphysis to define adults. Using high precision digital calipers (± 0.01 mm), four measurements were taken either on the left or right side of 91 walrus mandibles: 80 modern mandibles (70 known-sex specimens; 10 unknown-sex specimens) and 11 archaeological mandibles of unknown sex. We used linear discriminant function analysis (LDFA) to determine what measurements best distinguished Pacific walrus males from females. Minimum mandible thickness had the most predictive power, whereas mandible length, height, and depth, were less predictive. Posterior probabilities indicated that LDFA classified the known-sex Pacific walruses with 100% accuracy, and unknown sex with ≥ 90% probability. The ability to define the sex of unknown individuals accurately could greatly increase the sample size of future projects dealing with skeletal remains, and will improve future research efforts. Text Arctic Odobenus rosmarus Alaska walrus* BioOne Online Journals Arctic Pacific Journal of Mammalogy 101 4 941 950 |
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Open Polar |
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BioOne Online Journals |
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language |
English |
description |
Pacific walruses (Odobenus rosmarus divergens) play a vital role in Arctic marine ecosystems and the subsistence lifestyle of Alaska Native communities. Museum collections contain numerous archaeological and historic walrus specimens that have proven useful in a variety of studies; however, for many cases, the sex of these specimens is unknown. Sexes of adult (> 5 years determined by tooth aging) Atlantic walruses (Odobenus rosmarus rosmarus) have been accurately determined in previous studies using mandible measurements. We tested the validity of this approach for Pacific walruses, and used full fusion of the mandibular symphysis to define adults. Using high precision digital calipers (± 0.01 mm), four measurements were taken either on the left or right side of 91 walrus mandibles: 80 modern mandibles (70 known-sex specimens; 10 unknown-sex specimens) and 11 archaeological mandibles of unknown sex. We used linear discriminant function analysis (LDFA) to determine what measurements best distinguished Pacific walrus males from females. Minimum mandible thickness had the most predictive power, whereas mandible length, height, and depth, were less predictive. Posterior probabilities indicated that LDFA classified the known-sex Pacific walruses with 100% accuracy, and unknown sex with ≥ 90% probability. The ability to define the sex of unknown individuals accurately could greatly increase the sample size of future projects dealing with skeletal remains, and will improve future research efforts. |
author2 |
Nathan Taylor Casey T. Clark Nicole Misarti Lara Horstmann |
format |
Text |
author |
Nathan Taylor Casey T. Clark Nicole Misarti Lara Horstmann |
spellingShingle |
Nathan Taylor Casey T. Clark Nicole Misarti Lara Horstmann Determining sex of adult Pacific walruses from mandible measurements |
author_facet |
Nathan Taylor Casey T. Clark Nicole Misarti Lara Horstmann |
author_sort |
Nathan Taylor |
title |
Determining sex of adult Pacific walruses from mandible measurements |
title_short |
Determining sex of adult Pacific walruses from mandible measurements |
title_full |
Determining sex of adult Pacific walruses from mandible measurements |
title_fullStr |
Determining sex of adult Pacific walruses from mandible measurements |
title_full_unstemmed |
Determining sex of adult Pacific walruses from mandible measurements |
title_sort |
determining sex of adult pacific walruses from mandible measurements |
publisher |
American Society of Mammalogists |
publishDate |
2020 |
url |
https://doi.org/10.1093/jmammal/gyaa051 |
op_coverage |
world |
geographic |
Arctic Pacific |
geographic_facet |
Arctic Pacific |
genre |
Arctic Odobenus rosmarus Alaska walrus* |
genre_facet |
Arctic Odobenus rosmarus Alaska walrus* |
op_source |
https://doi.org/10.1093/jmammal/gyaa051 |
op_relation |
doi:10.1093/jmammal/gyaa051 |
op_rights |
All rights reserved. |
op_doi |
https://doi.org/10.1093/jmammal/gyaa051 |
container_title |
Journal of Mammalogy |
container_volume |
101 |
container_issue |
4 |
container_start_page |
941 |
op_container_end_page |
950 |
_version_ |
1800746837833940992 |