How large is large: estimating ecologically meaningful isotopic differences in observational studies of wild animals
International audience RATIONALE: In ecological studies of wildlife movements and foraging, bio-logging and isotopic data are routinely collected and increasingly analyzed in tandem. Such analyses have two shortcomings: (1) small sample size linked with the number of telemetric tags that can be depl...
Published in: | Rapid Communications in Mass Spectrometry |
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Main Authors: | , , , |
Other Authors: | , , , , , , , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
HAL CCSD
2012
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Subjects: | |
Online Access: | https://hal.science/hal-00741769 https://doi.org/10.1002/rcm.6389 |
Summary: | International audience RATIONALE: In ecological studies of wildlife movements and foraging, bio-logging and isotopic data are routinely collected and increasingly analyzed in tandem. Such analyses have two shortcomings: (1) small sample size linked with the number of telemetric tags that can be deployed, and (2) the observational nature of isotopic gradients. Wildlife ecologists are thus put in a statistical conundrum known as the small n, large p problem. METHODS: Using shrinkage regression, which directly addresses the issue of accurately estimating effects from sparse data, we studied what counts as a biologically meaningful isotopic difference (a prerequisite to delineate isoscapes) in the southern elephant seal (Mirounga leonina), a large and elusive marine predator. RESULTS: Seals foraging in Antarctic waters had a lower carbon isotopic value (by 2%) than seals foraging either in the interfrontal zone or on the Kerguelen Plateau. The latter two foraging strategies were indistinguishable on the sole basis of d 13 C values with our data. CONCLUSIONS: Shrinkage regression is a conservative statistical technique that has wide applicability in isotopic ecology to help separate robust biological signals from noise |
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