Testosterone-mediated effects on fitness-related phenotypic traits and fitness.
The physiological and behavioral mechanisms underlying life-history trade-offs are a continued source of debate. Testosterone (T) is one physiological factor proposed to mediate the trade-off between reproduction and survival. We use phenotypic engineering and multiple laboratory and field fitness-related phenotypic traits to test the effects of elevated T between two bank vole Myodes glareolus groups: dominant and subordinate males. Males with naturally high T levels showed higher social status (laboratory dominance) and mobility (distance between capture sites) than low-T males, and the effect of T on immune response was also T group specific, suggesting that behavioral strategies may exist in male bank voles due to the correlated responses of T. Exogenous T enhanced social status, mate searching (polygon of capture sites), mobility, and reproductive success (relative measure of pups sired). However, exogenous T also resulted in the reduction of immune function, but only in males from the high-T group. This result may be explained either by the immunosuppression costs of T or by differential sensitivity of different behavioral strategies to steroids. Circulating T levels were found to be heritable; therefore, female bank voles would derive indirect genetic benefits via good genes from mating with males signaling dominance.
Mills
Suzanne C
SC
Centre of Excellence in Evolutionary Research, Jyväskylä, University of Jyväskylä, Finland. mills@sooozie.co.uk
Grapputo
Alessandro
A
Jokinen
Ilmari
I
Koskela
Esa
E
Mappes
Tapio
T
Oksanen
Tuula A
TA
Poikonen
Tanja
T
D000818:Animals; D000906:Antibodies / Q000097:blood; D003411:Arvicolinae / Q000276:immunology / Q000502:physiology*; D005387:Finland; D006608:Hierarchy, Social; D007074:Immunoglobulin G / Q000097:blood; D016014:Linear Models; D008297:Male; D010641:Phenotype; D011863:Radioimmunoassay; D013037:Spatial Behavior / Q000502:physiology*; D013045:Species Specificity; D016019:Survival Analysis; D013739:Testosterone / Q000097:blood / Q000276:immunology / Q000502:physiology*
D000906:Antibodies; D007074:Immunoglobulin G; D013739:Testosterone