How many cubs can a mum nurse? Maternal age and size influence litter size in polar bears.
Biol Lett
; 15(5): 20190070, 2019 05 31.
Article
in En
| MEDLINE
| ID: mdl-31039729
ABSTRACT
Life-history theory predicts that females' age and size affect the level of maternal investment in current reproduction, balanced against the future reproductive effort, maintenance and survival. Using long-term (30 years) individual data on 193 female polar bears ( Ursus maritimus), we assessed age- and size-specific variation on litter size. Litter size varied with maternal age, younger females had higher chances of losing a cub during their first months of life. Results suggest an improvement in reproductive abilities early in life due to experience with subsequent reproductive senescence. Litter size increased with maternal size, indicating that size may reflect individual quality. We also found an optimum in the probability of having twins, suggesting stabilizing selection on female body size. Heterogeneity was observed among the largest females, suggesting that large size comes at a cost.
Key words
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Ursidae
Type of study:
Prognostic_studies
Limits:
Animals
/
Pregnancy
Language:
En
Journal:
Biol Lett
Journal subject:
BIOLOGIA
Year:
2019
Document type:
Article
Affiliation country:
France