大蟾蜍卵孵化的温度效应研究

为了解大蟾蜍卵的孵化率、发育起点温度、发育有效积温和蝌蚪成活率,将产出当天的大蟾蜍卵采集回实验室,分别置于5个不同温度(10℃、15℃、20℃、25℃和30℃)下孵化,观察和测量记录卵的孵化率、孵化后3 d蝌蚪的成活率、体长及每个温度下卵的发育历期。光照周期设为14L∶10D。结果表明:温度对大蟾蜍卵的孵化率影响显著;孵化后3 d蝌蚪的成活率随着温度的升高而降低,30℃下孵化的蝌蚪在2 d之内全部死亡;温度对大蟾蜍卵孵化后3 d蝌蚪全长的影响极显著(F=55.592,df=4,N=50,p<0.000 1),大蟾蜍的卵孵化后3 d蝌蚪的全长随着温度的升高而增加;应用直线回归法和直接最优化法算得的大蟾蜍卵的发育起点温度和有效积温分别为0.35℃、68.64℃/d和0.15℃、69.29℃/d。

Effect of temperature on egg incubation of the common giant toad

In order to understand the egg incubation ratio,thermal threshold of development,accumulative temperature and the percentage survival of the common giant toad,eggs of this species collected from the wild after production for only 2 days were cultured respectively at five different temperatures: 10℃,15℃, 20℃,25℃,and 30℃.The photoperiod was set to 14L:10D.The egg incubation ratio,percentage survival and body length of the tadpoles after incubation for 3 days,and length of incubation periods of the common giant toad at different temperatures were calculated or measured.Both the linear regression methods and the direct optimum methods were used to calculate the thermal thresholds of development and the effective sum of heat for the egg incubation of the common giant toad.The results indicated that the egg incubation ratio and the body length were significantly influenced by the incubation temperature,and that the percentage survival decreased with the increase of incubation temperature.The thermal thresholds of development for the egg incubation was 0.35℃ or 0.15℃.The effective sum of heat for the egg incubation was 68.64 ℃/d degree or 69.29℃/d the errors of which were caused by the differences between the calculating methods.It could be concluded that the effective sum of heat for the egg incubation of the common giant toad is about 68.93℃/d with a thermal threshold of development of 0.25℃.