McGlothlin J W, Jawor J M, Greives T J, Casto J M, Phillips J L, Ketterson E D
Department of Biology and Center for the Integrative Study of Animal Behavior, Indiana University, Bloomington, IN, USADepartment of Biological Sciences, The University of Southern Mississippi, Hattiesburg, MS, USADepartment of Biological Sciences, Illinois State University, Normal, IL, USABiology Department, The College of William & Mary, Williamsburg, VA, USA.
J Evol Biol. 2008 Jan;21(1):39-48. doi: 10.1111/j.1420-9101.2007.01471.x. Epub 2007 Nov 22.
When male investment in mating varies with quality, reliable sexual signals may evolve. In many songbirds, testosterone mediates mating investment, suggesting that signals should be linked to testosterone production. However, because testosterone may change rapidly during behaviour such as territorial aggression and courtship, efforts to establish such a relationship have proved challenging. In a population of dark-eyed juncos, we measured individual variation in the production of short-term testosterone increases by injecting gonadotropin-releasing hormone (GnRH). We found a positive correlation between the magnitude of these increases and the size of a plumage ornament ('tail white') previously shown to be important for female choice and male-male competition. We then measured naturally elevated testosterone levels produced during male-male competition and found that they covaried with those induced by GnRH. We suggest that the association between tail white and testosterone increases may allow conspecifics to assess potential mates and competitors reliably using tail white.
当雄性在交配方面的投入随质量而变化时，可靠的性信号可能会进化。在许多鸣禽中，睾酮介导交配投入，这表明信号应该与睾酮的产生相关联。然而，由于睾酮在诸如领地攻击和求偶等行为过程中可能会迅速变化，建立这种关系的努力已被证明具有挑战性。在一群暗眼灯草鹀中，我们通过注射促性腺激素释放激素（GnRH）来测量短期睾酮增加量的个体差异。我们发现这些增加量的大小与一种羽毛装饰（“尾部白色”）的大小呈正相关，先前已表明这种装饰对雌性选择和雄性间竞争很重要。然后我们测量了在雄性间竞争期间自然升高的睾酮水平，发现它们与GnRH诱导的睾酮水平相关。我们认为，尾部白色与睾酮增加之间的关联可能使同种个体能够可靠地利用尾部白色来评估潜在配偶和竞争对手。
