Lactation patterns of pinnipeds are not explained by optimization of maternal energy delivery rates

Within pinnipeds, phocids and otariids show differing maternal care. strategies. Phocids rear young out of body stores in a yearly cycle with a single stay ashore when the mother fasts while lactating, whereas otariids provision their young by repeated foraging trips to sea alternating with brief st...

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Bibliographic Details
Published in:Behavioral Ecology and Sociobiology
Main Authors: Trillmich, F., Weissing, F.J.
Format: Article in Journal/Newspaper
Language:English
Published: 2006
Subjects:
lactation strategy
life history
phylogenctic constraint
income breeding
capital breeding
allometric relationships
reproductive value
optimality approach
ANTARCTIC FUR SEALS
AMSTERDAM ISLAND
ARCTOCEPHALUS-GALAPAGOENSIS
CYSTOPHORA-CRISTATA
PHOCA-GROENLANDICA
FORAGING EFFORT
BODY CONDITION
HOODED SEAL
HARP SEAL
FEMALE
Antarctic
Amsterdam Island
Antarc*
Antarctic Fur Seal
Antarctic Fur Seals
Cystophora cristata
Harp Seal
hooded seal
Phoca groenlandica
Online Access:https://hdl.handle.net/11370/972d7bb9-b8ab-4ee7-b24e-3ed81a21739a
https://research.rug.nl/en/publications/972d7bb9-b8ab-4ee7-b24e-3ed81a21739a
https://doi.org/10.1007/s00265-005-0150-4
Description
Summary:Within pinnipeds, phocids and otariids show differing maternal care. strategies. Phocids rear young out of body stores in a yearly cycle with a single stay ashore when the mother fasts while lactating, whereas otariids provision their young by repeated foraging trips to sea alternating with brief stays ashore where they suckle their young. In a previous optimality model, these differences have been interpreted as adaptations based on differing energy requirements of large (phocid) and smaller (otariid) species, and the time budget of the large elephant and the much smaller Antarctic fur seal were correctly predicted. Our refined model-extended to pinniped species of all sizes-predicts lactation strategies to shift from attendance cycles to 1-year cycles with increasing body mass and provides an explanation for the finding that phocid pups are weaned at lower relative mass than otariid pups. However, other predictions do not correspond to empirical findings. In particular, the model does not explain the behavior of large otariids and small phocids. Thus, maternal metabolic requirements alone appear insufficient to explain observed lactation patterns. In the light of our results, we discuss more generally the scope and limitations of optimality models when applied in a comparative framework to a group of related species.

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