Institute of Zoology, University of Zurich, Winterthurerstrasse 190, Zurich, Switzerland.
Am Nat. 2009 Mar;173(3):376-88. doi: 10.1086/596535.
The relative plasticity hypothesis predicts that alternative tactics are associated with changes in steroid hormone levels. In species with alternative male reproductive tactics, the highest androgen levels have usually been reported in dominant males. However, in sociable species, dominant males show amicable behaviors to gain access to females, which might conflict with high testosterone levels. We compared testosterone, corticosterone, and resting metabolic rate in male striped mice (Rhabdomys pumilio) following a conditional strategy with three different reproductive tactics: (i) philopatric group-living males, (ii) solitary-living roamers, (iii) dominant but sociable group-living territorial breeders. Philopatrics had the lowest testosterone but highest corticosterone levels, suggesting that they make the best of a bad job. Dominant territorial breeders had lower testosterone levels than roamers, which have a lower competitive status. Roamers had the highest testosterone levels, which might promote risky behavior, such as invading territories defended by territorial males. Roamers also had lower resting metabolic rates than either type of group-living males. Our results suggest that dominant males' testosterone levels reflect a trade-off between low testosterone amicable behavior and high testosterone dominance behavior.
相对可塑性假说预测，替代策略与类固醇激素水平的变化有关。在具有替代雄性生殖策略的物种中，通常在占优势的雄性中报告最高的雄激素水平。然而，在社会性物种中，优势雄性通过表现出友好的行为来接近雌性，这可能与高睾酮水平相冲突。我们比较了条纹小鼠（Rhabdomys pumilio）的雄性在三种不同生殖策略后的睾酮、皮质酮和静息代谢率：（i）亲代群体居住的雄性，（ii）独居游荡的雄性，（iii）优势但社交的群体居住的有领地繁殖的雄性。亲代雄性的睾酮最低，但皮质酮水平最高，这表明它们充分利用了不利的情况。占优势的有领地繁殖的雄性的睾酮水平低于游荡雄性，后者的竞争地位较低。游荡雄性的睾酮水平最高，这可能促进了冒险行为，例如入侵由有领地的雄性守护的领地。游荡雄性的静息代谢率也低于任何一种群居雄性。我们的结果表明，优势雄性的睾酮水平反映了低睾酮友好行为和高睾酮支配行为之间的权衡。
