Aspartic acid racemization rate in narwhal (Monodon monoceros) eye lens nuclei estimated by counting of growth layers in tusks
Ages of marine mammals have traditionally been estimated by counting dentinal growth layers in teeth. However, this method is difficult to use on narwhals (Monodon monoceros) because of their special tooth structures. Alternative methods are therefore needed. The aspartic acid racemization (AAR) tec...
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Norwegian Polar Institute
2012
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Online Access: | https://doi.org/10.3402/polar.v31i0.15865 https://doaj.org/article/260bbd00bf204c24b0370a88d0543e39 |
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fttriple:oai:gotriple.eu:oai:doaj.org/article:260bbd00bf204c24b0370a88d0543e39 2023-05-15T16:29:53+02:00 Aspartic acid racemization rate in narwhal (Monodon monoceros) eye lens nuclei estimated by counting of growth layers in tusks Eva Garde Susanne Ditlevsen Steen H. Hansen Mads Peter Heide-Jørgensen 2012-11-01 https://doi.org/10.3402/polar.v31i0.15865 https://doaj.org/article/260bbd00bf204c24b0370a88d0543e39 en eng Norwegian Polar Institute doi:10.3402/polar.v31i0.15865 0800-0395 1751-8369 https://doaj.org/article/260bbd00bf204c24b0370a88d0543e39 undefined Polar Research, Vol 31, Iss 0, Pp 1-7 (2012) Age estimation Greenland species-specific racemization rate growth layers groups envir demo Journal Article https://vocabularies.coar-repositories.org/resource_types/c_6501/ 2012 fttriple https://doi.org/10.3402/polar.v31i0.15865 2023-01-22T17:53:24Z Ages of marine mammals have traditionally been estimated by counting dentinal growth layers in teeth. However, this method is difficult to use on narwhals (Monodon monoceros) because of their special tooth structures. Alternative methods are therefore needed. The aspartic acid racemization (AAR) technique has been used in age estimation studies of cetaceans, including narwhals. The purpose of this study was to estimate a species-specific racemization rate for narwhals by regressing aspartic acid d/l ratios in eye lens nuclei against growth layer groups in tusks (n=9). Two racemization rates were estimated: one by linear regression (r2=0.98) based on the assumption that age was known without error, and one based on a bootstrap study, taking into account the uncertainty in the age estimation (r2 between 0.88 and 0.98). The two estimated 2kAsp values were identical up to two significant figures. The 2k Asp value from the bootstrap study was found to be 0.00229±0.000089 SE, which corresponds to a racemization rate of 0.00114−yr±0.000044 SE. The intercept of 0.0580±0.00185 SE corresponds to twice the (d/l)0 value, which is then 0.0290±0.00093 SE. We propose that this species-specific racemization rate and (d/l)0 value be used in future AAR age estimation studies of narwhals, but also recommend the collection of tusks and eyes of narwhals for further improving the (d/l)0 and 2kAsp estimates obtained in this study. Article in Journal/Newspaper Greenland Monodon monoceros narwhal* Polar Research Unknown Greenland Polar Research 31 1 15865 |
institution |
Open Polar |
collection |
Unknown |
op_collection_id |
fttriple |
language |
English |
topic |
Age estimation Greenland species-specific racemization rate growth layers groups envir demo |
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Age estimation Greenland species-specific racemization rate growth layers groups envir demo Eva Garde Susanne Ditlevsen Steen H. Hansen Mads Peter Heide-Jørgensen Aspartic acid racemization rate in narwhal (Monodon monoceros) eye lens nuclei estimated by counting of growth layers in tusks |
topic_facet |
Age estimation Greenland species-specific racemization rate growth layers groups envir demo |
description |
Ages of marine mammals have traditionally been estimated by counting dentinal growth layers in teeth. However, this method is difficult to use on narwhals (Monodon monoceros) because of their special tooth structures. Alternative methods are therefore needed. The aspartic acid racemization (AAR) technique has been used in age estimation studies of cetaceans, including narwhals. The purpose of this study was to estimate a species-specific racemization rate for narwhals by regressing aspartic acid d/l ratios in eye lens nuclei against growth layer groups in tusks (n=9). Two racemization rates were estimated: one by linear regression (r2=0.98) based on the assumption that age was known without error, and one based on a bootstrap study, taking into account the uncertainty in the age estimation (r2 between 0.88 and 0.98). The two estimated 2kAsp values were identical up to two significant figures. The 2k Asp value from the bootstrap study was found to be 0.00229±0.000089 SE, which corresponds to a racemization rate of 0.00114−yr±0.000044 SE. The intercept of 0.0580±0.00185 SE corresponds to twice the (d/l)0 value, which is then 0.0290±0.00093 SE. We propose that this species-specific racemization rate and (d/l)0 value be used in future AAR age estimation studies of narwhals, but also recommend the collection of tusks and eyes of narwhals for further improving the (d/l)0 and 2kAsp estimates obtained in this study. |
format |
Article in Journal/Newspaper |
author |
Eva Garde Susanne Ditlevsen Steen H. Hansen Mads Peter Heide-Jørgensen |
author_facet |
Eva Garde Susanne Ditlevsen Steen H. Hansen Mads Peter Heide-Jørgensen |
author_sort |
Eva Garde |
title |
Aspartic acid racemization rate in narwhal (Monodon monoceros) eye lens nuclei estimated by counting of growth layers in tusks |
title_short |
Aspartic acid racemization rate in narwhal (Monodon monoceros) eye lens nuclei estimated by counting of growth layers in tusks |
title_full |
Aspartic acid racemization rate in narwhal (Monodon monoceros) eye lens nuclei estimated by counting of growth layers in tusks |
title_fullStr |
Aspartic acid racemization rate in narwhal (Monodon monoceros) eye lens nuclei estimated by counting of growth layers in tusks |
title_full_unstemmed |
Aspartic acid racemization rate in narwhal (Monodon monoceros) eye lens nuclei estimated by counting of growth layers in tusks |
title_sort |
aspartic acid racemization rate in narwhal (monodon monoceros) eye lens nuclei estimated by counting of growth layers in tusks |
publisher |
Norwegian Polar Institute |
publishDate |
2012 |
url |
https://doi.org/10.3402/polar.v31i0.15865 https://doaj.org/article/260bbd00bf204c24b0370a88d0543e39 |
geographic |
Greenland |
geographic_facet |
Greenland |
genre |
Greenland Monodon monoceros narwhal* Polar Research |
genre_facet |
Greenland Monodon monoceros narwhal* Polar Research |
op_source |
Polar Research, Vol 31, Iss 0, Pp 1-7 (2012) |
op_relation |
doi:10.3402/polar.v31i0.15865 0800-0395 1751-8369 https://doaj.org/article/260bbd00bf204c24b0370a88d0543e39 |
op_rights |
undefined |
op_doi |
https://doi.org/10.3402/polar.v31i0.15865 |
container_title |
Polar Research |
container_volume |
31 |
container_issue |
1 |
container_start_page |
15865 |
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1766019587565944832 |