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Sex-specific aging in bite force in a wild vertebrate
Erynn J Rebol1, David J Anderson1
1Dept. of Biology, Wake Forest University, Winston-Salem, NC 27106, USA.
Experimental Gerontology
|December 19, 2021
Summary
Male and female Nazca boobies show age-related decline in bite force. However, this decline begins later in life for males, suggesting sex-specific aging patterns in muscle function for this long-lived seabird species.
Area of Science:
- Gerontology
- Animal Ecology
- Physiology
Background:
- Sex differences in senescence are expected due to physiological variations.
- Assessing age-related physiological decline in wild, long-lived animals presents significant methodological challenges.
- Muscle strength decline, a key aspect of aging, has been understudied in wild vertebrates.
Purpose of the Study:
- To investigate sex-specific patterns of senescent decline in muscle strength using bite force as a functional indicator in Nazca boobies (Sula granti).
- To test the hypothesis that slower accumulation of reproductive costs in males, due to a male-biased sex ratio, delays muscle strength decline compared to females.
Main Methods:
- Utilized bite force, measured with a force transducer, as a proxy for muscle strength in known-age Nazca boobies.
- Collected data from 349 adult birds during the breeding season on Isla Española, Galápagos.
- Analyzed age-related changes in bite force, comparing patterns between males and females.
Main Results:
- Both male and female Nazca boobies exhibited a decline in bite force with increasing age.
- The onset of bite force decline was observed at a later age in males than in females.
- This finding provides evidence for sex-specific schedules of muscle function decline in a wild vertebrate species.
Conclusions:
- Senescent decline in muscle function occurs in both sexes of Nazca boobies, but at different rates.
- The results support the hypothesis of delayed aging of muscle strength in males, potentially linked to reproductive constraints.
- This study highlights the importance of considering sex-specific differences in aging processes within wild populations.
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