“Nose-metrics” of wild southern elephant seal (Mirounga leonina) males using image analysis and geometric morphometrics

Filippo Galimberti, Simona Sanvito, Maria Chiara Vinesi, Andrea Cardini

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1 Citation (Scopus)

Abstract

The elephant seal (genus Mirounga) proboscis is a textbook example of an exaggerated secondary sexual trait, whose function is debated. The proboscis can be related to sexual status advertising, emission of aggressive vocalizations, and/or female mating choice. The study of the proboscis is complicated, because it is a soft trait that needs to be studied when males vocalize and it is thus expanded. Here, we combined field stimulation experiments, 2D photogrammetry, and geometric morphometrics, to study the proboscis of wild elephant seals in natural conditions. The goal of our study was twofold: (a) to demonstrate that photogrammetry and geometric morphometrics can be effectively applied in the field to wild, large, non-sedated mammals; (b) to study the proboscis shape development during maturation. We found that it is possible to accurately estimate the proboscis size and shape using photographs of vocalizing males taken in the field. Moreover, we showed that mature and non-mature males differ not only in proboscis size but also in its shape, a difference that is largely allometric and can have important effects on the frequency structure and individual signature of male vocalizations. These results open new avenues for future research on this enigmatic structure, its function in aggressive displays and potential role in sexual selection, and also exemplify a very promising approach, that could be applied in field studies of other large mammals.

Original languageEnglish
JournalJournal of Zoological Systematics and Evolutionary Research
DOIs
Publication statusE-pub ahead of print - 10 Mar 2019

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Earless Seals
Mirounga leonina
proboscis
elephant
Nose
image analysis
Photogrammetry
Mirounga
vocalization
photogrammetry
Mammals
mammal
Textbooks
textbook
sexual selection
photograph
maturation
mammals
photographs
experiment

Cite this

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title = "“Nose-metrics” of wild southern elephant seal (Mirounga leonina) males using image analysis and geometric morphometrics",
abstract = "The elephant seal (genus Mirounga) proboscis is a textbook example of an exaggerated secondary sexual trait, whose function is debated. The proboscis can be related to sexual status advertising, emission of aggressive vocalizations, and/or female mating choice. The study of the proboscis is complicated, because it is a soft trait that needs to be studied when males vocalize and it is thus expanded. Here, we combined field stimulation experiments, 2D photogrammetry, and geometric morphometrics, to study the proboscis of wild elephant seals in natural conditions. The goal of our study was twofold: (a) to demonstrate that photogrammetry and geometric morphometrics can be effectively applied in the field to wild, large, non-sedated mammals; (b) to study the proboscis shape development during maturation. We found that it is possible to accurately estimate the proboscis size and shape using photographs of vocalizing males taken in the field. Moreover, we showed that mature and non-mature males differ not only in proboscis size but also in its shape, a difference that is largely allometric and can have important effects on the frequency structure and individual signature of male vocalizations. These results open new avenues for future research on this enigmatic structure, its function in aggressive displays and potential role in sexual selection, and also exemplify a very promising approach, that could be applied in field studies of other large mammals.",
keywords = "2D photogrammetry, measurement error, pinnipeds, proboscis, semilandmarks",
author = "Filippo Galimberti and Simona Sanvito and Vinesi, {Maria Chiara} and Andrea Cardini",
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AU - Cardini, Andrea

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