Selection experiments to increase the proportion of males in Nile tilapia (Oreochromis niloticus) by means of temperature treatment
Selection experiments to increase the proportion of males in Nile tilapia (Oreochromis niloticus) by means of temperature treatment
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DOI：
10.1016/j.aquaculture.2007.08.009
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发表时间：
2007
期刊：
影响因子：
4.5
通讯作者：
S. Wessels;G. Hörstgen-Schwark
中科院分区：
文献类型：
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作者：
S. Wessels;G. Hörstgen-Schwark
对尼罗罗非鱼进行了两代选择试验。niloticus，Lake Manzala，Egypt）来测试温度处理后雄性的比例是否可以持续地受到选择的影响。从45个家庭作为基础人口开始，以下列方式对这些家庭的热敏感性进行了测试。在28 °C下孵育9天后，将每个家庭的鱼苗细分为对照组（28 °C）和处理组，每组由110条鱼组成。处理组在36 °C的温度下保持10天。此后，处理的鱼苗再次逐渐适应28 °C。每个处理组和相应的对照组分别饲养，直至进行性别鉴定（通过在最小90日龄时对性腺进行显微镜检查）。从每个家庭的对照组中随机抽取10名男性和女性，以供日后选择。处理组中雄性的百分比是选择标准，选择温度处理后雄性超过80%或低于60%的家系。在两个世代（G 0和G1）中，约14%的测试家庭被选择产生两个不同的线（高和低线），显示出高或低的反应，温度处理的性别比例。在第一、二代选择中，高、低两代分别测得66、26个家系和72、13个家系。经过两个世代的选择，高温处理组的高品系雄性比例为90%，而弱敏感低品系的平均雄性比例为54%。由连续世代累积的实现选择反应和-差估计的实现遗传力，高、低品系分别为0.69和0.86。这项研究提供了第一个证据表明，过剩的男性在温度处理组可以选择作为一个数量性状。因此，温度敏感线可以作为一个消费者和环境友好的方法，显着增加尼罗罗非鱼的男性比例，如果大量的亲鱼可以进行测试。
A two generation selection experiment in Nile tilapia (O. niloticus, Lake Manzala, Egypt) was carried out to test whether the proportion of males after temperature treatment could be sustainably influenced by selection. Starting with 45 families as a base population the families were tested for their thermal sensitivity in the following way. After a 9-day incubation period at 28 °C, fry of each family were subdivided into a control (28 °C) and a treatment group, each consisting of 110 fish. The treatment group was kept at a temperature of 36 °C for 10 days. Thereafter treated fry were gradually adapted to 28 °C again. Each treatment and corresponding control group was raised separately until sexing (by microscopic inspection of gonad squashes at a minimum age of 90 days). A random sample of ten males and females from control groups of each family was kept for later selection decisions. The percentage of males in treatment groups was the selection criterion and the families showing more than 80% males or less than 60% after temperature treatment were selected. Over two generations (G0 and G1) around 14% of the tested families were selected to produce two divergent lines (high and low line) which showed a high or low response to temperature treatment regarding their sex ratios. In the first and second generation of selection 66 and 26 families were tested in the high line and 72 and 13 families in the low line, respectively. After two generations of selection the temperature treated groups in the high line showed a male percentage of 90%, whereas the weakly sensitive low line showed an average male proportion of 54%. The realized heritability estimated from the cumulated realized selection response and -differential in successive generations was 0.69 in the high line and 0.86 in the low line. This study provides the first evidence that a surplus of males in temperature treated groups can be selected for as a quantitative trait. Thus, temperature sensitive lines could be produced as a consumer- and environment-friendly approach to significantly increase the proportion of males in Nile tilapia, if large numbers of broodstock could be tested.