Rodriguez-Barreto Deiene, Rey Olivier, Uren-Webster Tamsyn M, Castaldo Giovanni, Consuegra Sonia, Garcia de Leaniz Carlos
Centre for Sustainable Aquatic Research (CSAR), College of Science Swansea University Swansea UK.
Université de Perpignan Via Domitia Perpignan France.
Evol Appl. 2019 Jul 17;12(9):1757-1771. doi: 10.1111/eva.12830. eCollection 2019 Oct.
To meet future global demand for fish protein, more fish will need to be farmed using fewer resources, and this will require the selection of nonaggressive individuals that perform well at high densities. Yet, the genetic changes underlying loss of aggression and adaptation to crowding during aquaculture intensification are largely unknown. We examined the transcriptomic response to aggression and crowding in Nile tilapia, one of the oldest and most widespread farmed fish, whose social structure shifts from social hierarchies to shoaling with increasing density. A mirror test was used to quantify aggression and skin darkening (a proxy for stress) of fish reared at low and high densities, and gene expression in the hypothalamus was analysed among the most and least aggressive fish at each density. Fish reared at high density were darker, had larger brains, were less active and less aggressive than those reared at low density and had differentially expressed genes consistent with a reactive stress-coping style and activation of the hypothalamus-pituitary-interrenal (HPI) axis. Differences in gene expression among aggressive fish were accounted for by density and the interaction between density and aggression levels, whereas for nonaggressive fish differences in gene expression were associated with individual variation in skin brightness and social stress. Thus, the response to crowding in Nile tilapia is context dependent and involves different neuroendocrine pathways, depending on social status. Knowledge of genes associated with the response to crowding may pave the way for more efficient fish domestication, based on the selection of nonaggressive individuals with increasing tolerance to chronic stress necessary for aquaculture intensification.
为满足未来全球对鱼类蛋白质的需求，需要利用更少的资源养殖更多的鱼，这将需要选择在高密度环境下表现良好的非攻击性个体。然而，水产养殖集约化过程中攻击行为丧失和适应拥挤的潜在遗传变化在很大程度上尚不清楚。我们研究了尼罗罗非鱼对攻击和拥挤的转录组反应，尼罗罗非鱼是最古老、分布最广的养殖鱼类之一，其社会结构会随着密度增加从社会等级制度转变为群居。我们使用镜像测试来量化低密度和高密度养殖的鱼的攻击性和皮肤变黑程度（作为应激的指标），并分析每种密度下最具攻击性和最不具攻击性的鱼的下丘脑基因表达。与低密度养殖的鱼相比，高密度养殖的鱼颜色更深、大脑更大、活动更少、攻击性更低，并且具有与应激反应应对方式和下丘脑-垂体-肾间组织（HPI）轴激活一致的差异表达基因。攻击性鱼之间的基因表达差异由密度以及密度与攻击水平之间的相互作用决定，而对于非攻击性鱼，基因表达差异与皮肤亮度的个体差异和社会应激有关。因此，尼罗罗非鱼对拥挤的反应取决于环境，并且根据社会地位涉及不同的神经内分泌途径。了解与对拥挤反应相关的基因可能为更高效的鱼类驯化铺平道路，这基于选择对水产养殖集约化所需的慢性应激耐受性增强的非攻击性个体。
