Sex determination and temperature-induced sex differentiation in three natural populations of Nile tilapia (Oreochromis niloticus) adapted to extreme temperature conditions
Sex determination and temperature-induced sex differentiation in three natural populations of Nile tilapia (Oreochromis niloticus) adapted to extreme temperature conditions
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DOI：
10.1016/j.aquaculture.2007.07.227
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发表时间：
2007-01-01
期刊：
影响因子：
4.5
通讯作者：
Baroiller, Jean-Francois
中科院分区：
文献类型：
--
作者：
Bezault, Etienne;Clota, Frederic;Baroiller, Jean-Francois
尼罗罗非鱼(Oreochromis Niloticus)作为水产养殖的重要物种，其性别决定系统受到了广泛的研究。在该物种中，性别决定被认为是由一个复杂的遗传性别决定因素系统(GSD)和关键时期的温度影响(TSD)之间的相互作用决定的。以前的研究完全是在国内种群上进行的，与遗传和维持限制相关。考虑到尼罗罗非鱼的广泛分布和适应潜力，我们在受控条件下调查了自然种群适应三种极端热力制度的性别决定系统：埃塞俄比亚稳定的极端环境，高原湖(科卡湖)的寒冷温度，或热泉(梅塔哈拉湖)的温暖温度，以及加纳的季节变化很大的环境(坎杜，伏尔塔湖)。性比分析是在卵黄囊吸收后30天内，在恒定的基础温度(27摄氏度)或高温(36摄氏度)下饲养的后代。在标准温度下饲养的后代的性别比表明，这三个群体共享一个相似的复杂的GSD系统，其基础是以男性异性交配为主的因素，以及该基因座的多态和/或次要因素的作用。这三个群体对性别分化表现出明显的温度敏感性，反应强度因父母而异。这证实了尼罗罗非鱼TSD中存在基因-环境互作。此外，强烈建议在两个种群(Kanda u和Koka)中存在自然性别颠倒的个体。然而，这里不可能推断性别反转是否是微小的遗传因素和/或环境影响造成的。本研究首次证明了尼罗罗非鱼天然群体中具有多态GSD和TSD组分的复合SDS的保守性。我们讨论了我们的发现的进化论含义，并强调了性别决定的实地调查的重要性。(C)2007 Elsevier B.V.保留所有权利。
As a species of major interest for aquaculture, the sex determination system (SDS) of Nile tilapia, Oreochromis niloticus, has been widely investigated. In this species, sex determination is considered to be governed by the interactions between a complex system of genetic sex determination factors (GSD) and the influence of temperature (TSD) during a critical period. Previous studies were exclusively carried out on domestic stocks with the genetic and maintenance limitations associated. Given the wide distribution and adaptation potential of the Nile tilapia, we investigated under controlled conditions the sex determination system of natural populations adapted to three extreme thermal regimes: stable extreme environments in Ethiopia, either cold temperatures in a highland lake (Lake Koka), or warm temperatures in hydrothermal springs (Lake Metahara), and an environment with large seasonal variations in Ghana (Kpandu, Lake Volta). The sex ratio analysis was conducted on progenies reared under constant basal (27 degrees C) or high (36 degrees C) temperatures during the 30 days following yolk-sac resorption. Sex ratios of the progenies reared at standard temperature suggest that the three populations share a similar complex GSD system based on a predominant male heterogametic factor with additional influences of polymorphism at this locus and/or action of minor factors. The three populations presented a clear thermosensitivity of sex differentiation, with large variations in the intensity of response depending on the parents. This confirms the presence of genotype-environment interactions in TSD of Nile tilapia. Furthermore the existence of naturally sex-reversed individuals is strongly suggested in two populations (Kpandu and Koka). However, it was not possible here to infer if the sex-inversion resulted from minor genetic factors and/or environmental influences. The present study demonstrated for the first time the conservation of a complex SDS combining polymorphic GSD and TSD components in natural populations of Nile tilapia. We discuss the evolutionary implications of our findings and highlight the importance of field investigations of sex determination. (c) 2007 Elsevier B.V. All rights reserved.