Penick Clint A, Brent Colin S, Dolezal Kelly, Liebig Jürgen
School of Life Sciences, Arizona State University, Tempe, AZ 85287-4501, USA.
J Exp Biol. 2014 May 1;217(Pt 9):1496-503. doi: 10.1242/jeb.098301. Epub 2014 Jan 16.
Dominance rank in animal societies is correlated with changes in both reproductive physiology and behavior. In some social insects, dominance status is used to determine a reproductive division of labor, where a few colony members reproduce while most remain functionally sterile. Changes in reproduction and behavior in this context must be coordinated through crosstalk between the brain and the reproductive system. We investigated a role for biogenic amines in forming this connection in the ant Harpegnathos saltator. In this species, workers engage in an elaborate dominance tournament to establish a group of reproductive workers termed gamergates. We analyzed biogenic amine content in the brains of gamergates, inside-workers and foragers under stable colony conditions and found that gamergates had the highest levels of dopamine. Dopamine levels were also positively correlated with increased ovarian activity among gamergates. Next, we experimentally induced workers to compete in a reproductive tournament to determine how dopamine may be involved in the establishment of a new hierarchy. Dopamine levels rose in aggressive workers at the start of a tournament, while workers that were policed by their nestmates (a behavior that inhibits ovarian activity) showed a rapid decline in dopamine. In addition to dopamine, levels of serotonin and tyramine differed among castes, and these changes could contribute to differences in caste-specific behavioral patterns observed among non-reproductive workers. Overall, these results provide support that biogenic amines link changes in behavior and dominance with reproductive activity in H. saltator as well as drive differences in worker task performance.
动物社会中的优势等级与生殖生理和行为的变化相关。在一些社会性昆虫中，优势地位用于确定生殖分工，即少数群体成员进行繁殖，而大多数成员保持功能性不育。在这种情况下，生殖和行为的变化必须通过大脑与生殖系统之间的相互作用来协调。我们研究了生物胺在蚂蚁印度跳蚁形成这种联系中的作用。在这个物种中，工蚁会进行一场精心设计的优势竞争，以建立一群被称为生殖工蚁的群体。我们分析了在稳定群体条件下生殖工蚁、内勤工蚁和觅食工蚁大脑中的生物胺含量，发现生殖工蚁的多巴胺水平最高。多巴胺水平也与生殖工蚁卵巢活动的增加呈正相关。接下来，我们通过实验诱导工蚁参与生殖竞争，以确定多巴胺可能如何参与新等级制度的建立。在竞争开始时，具有攻击性的工蚁多巴胺水平上升，而受到同巢伙伴监管（一种抑制卵巢活动的行为）的工蚁多巴胺水平迅速下降。除了多巴胺，不同蚁型的血清素和酪胺水平也有所不同，这些变化可能导致在非生殖工蚁中观察到的蚁型特异性行为模式的差异。总体而言，这些结果支持生物胺将印度跳蚁的行为和优势变化与生殖活动联系起来，并驱动工蚁任务表现的差异。
