Trade-offs between reproduction and health in free-ranging African striped mice
Résumé
Energy is limited and must be allocated among
competing life-history traits. Reproduction is considered
one of the most energetically demanding life-history stages.
Therefore, the amount of energy an individual invests in
reproduction might carry fitness costs through reduced
energy allocation to other activities such as health maintenance.
We investigated whether reproduction impacts
health in the seasonally breeding African striped mouse
(Rhabdomys pumilio). We measured health in individuals
that reproduced (breeders) and individuals that did
not reproduce (their adult offspring) and tested whether:
(1) breeders’ health before reproduction was similar to
that of their offspring (representing a baseline); (2) breeders’
health deteriorated after reproduction; (3) breeders’
health after reproduction was worse than that of their offspring.
We collected blood samples from 12 breeding
females and 11 breeding males both at the onset and at
the end of the breeding season and from 12 adult daughters
and 11 adult sons that did not reproduce at the end of the breeding season. Health was assessed using serum
biochemistry analysis with VetScan Abaxis. Breeders differed
considerably in their health before and after reproduction,
particularly in parameters associated with digestion
(lower amylase in males), metabolism (lower albumin,
alkaline phosphatase, creatinine and glucose), osmoregulation
(lower potassium and phosphorous in females) and
immunity (higher globulin and altered alanine aminotransferase).
Our results suggest that with the onset of breeding
striped mice shifted their energy allocation from maintaining
health to reproduction, indicating that investment into
reproduction carries significant health costs.