Hello MARMAM Members,
On behalf of my colleagues and myself, I am pleased to share our new paper
“Determining sex of adult Pacific walruses from mandible measurements”, now
available on early view at the Journal of Mammalogy. The article can be
accessed here: https://bit.ly/2BtEpfC <https://bit.ly/2BtEpfC>
Taylor, N., C.T. Clark, N. Misarti, and L. Horstmann. 2020. Determining sex of
adult Pacific walruses from mandible measurements. Journal of Mammalogy:
XX(X):1-10 doi:10.1093/jmammal/gyaa051
Abstract:
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.
I am happy to provide a PDF of the article upon request. Please email me
(ctcl...@uw.edu <mailto:ctcl...@uw.edu>) or the lead author
(natayl...@alaska.edu <mailto:natayl...@alaska.edu>) if you are interested, or
if you have any questions about the paper.
Best regards,
Casey Clark
JISAO Postdoc
University of Washington
ctcl...@uw.edu <mailto:ctcl...@uw.edu>
_______________________________________________
MARMAM mailing list
MARMAM@lists.uvic.ca
https://lists.uvic.ca/mailman/listinfo/marmam
