Kagawa Nao
Department of Life Science, Faculty of Science and Technology, Kinki University, Higashiosaka, Osaka 577-8502, Japan.
Zoolog Sci. 2014 Mar;31(3):116-21. doi: 10.2108/zsj.31.116.
This study compared aggressiveness between two distinct wild populations of Japanese medaka: a Northern population, Oryzias sakaizumii, and a Southern population, O. latipes. When four males competed in intra-population contests, the social hierarchy was determined based on aggressive acts in both populations. Dominants of the Southern population showed higher aggressive acts than did dominants of the Northern population. Increased aggressiveness of Southern males compared with Northern males was also observed when a pair of Northern and Southern males were compared in inter-population contests. High expression of arginine vasotocin (AVT) in distinct preoptic regions were found in dominants and subordinates of the Southern population, but not in those of the Northern population. In contrast, neither 11-ketotestosterone nor cortisol levels in plasma differed between dominants and subordinates of either population, nor between pairs of the Northern and the Southern males. Taken together, these findings indicate that the two wild populations of medaka represent intriguing models for the study of neuroendocrinological correlates in behavioral traits underlying congeners of medaka fish.
一个是北方种群坂井青鳉（Oryzias sakaizumii），另一个是南方种群青鳉（O. latipes）。当四只雄性在种群内竞争时，两个种群的社会等级都是根据攻击行为来确定的。南方种群的优势个体比北方种群的优势个体表现出更高的攻击行为。当在种群间竞争中比较一对北方和南方雄性时，也观察到南方雄性比北方雄性的攻击性增强。在南方种群的优势个体和从属个体的不同视前区中发现精氨酸加压催产素（AVT）的高表达，但在北方种群中未发现。相比之下，两个种群的优势个体和从属个体之间，以及北方和南方雄性配对之间，血浆中的11-酮睾酮和皮质醇水平均无差异。综上所述，这些发现表明，青鳉的这两个野生种群是研究青鳉鱼类行为特征中神经内分泌相关性的有趣模型。
