方形网纹溞2种生殖模式的转换条件

Transformation conditions of two reproductive patterns In Ceriodaphnia quadrangula

在实验室条件下研究了种群密度、温度和光照时长诱导方形网纹溞产生两性生殖的条件.统计发现,在适宜的条件下,方形网纹溞主要繁殖方式是孤雌生殖,种群密度迅速增大.当种群处于较高的密度时(≥3/mL),两性生殖的产物——休眠卵的产量逐渐增加.种群密度为3/mL时,两性生殖的个体占种群数量的最大比例是15%;密度为6/mL时,比例是19%;密度达到9/mL时,比例上升到了24%,这显示高种群密度是促使孤雌生殖向两性生殖转换的主要因素.充足的食物、适宜的温度和光照时长等条件可以提高方形网纹溞两性生殖出现的概率,这是通过对方形网纹溞种群密度的提高而间接地改变其生殖模式的.这表明,种群内因素在方形网纹溞生殖转换的调控机制中起着重要作用.

The study of population density, temperature and photoperiod in laboratory conditions induced the development of Ceriodaphnia quadrangula to produce sexual reproduction.It is found that under the suitable conditions , the C. quadrangula are mainly propagated by parthenogenesis, and the population density increases rapidly. Experiments have found that at higher population densities (≥3/mL), the yield of dormant eggs, which are the product of sexual reproduction, increases with population density.When the population density of C. quadrangula is 3/mL, the maximum proportion of individuals in sexual reproduction is 15%. When the population density is 6/mL, the maximum proportion of individuals in sexual reproduction is 19%. When the population density of the daphnia reached 9/mL, the proportion rises to 24%, indicating that high population density is the main factor driving the transformation of parthenogenesis to sexual reproduction. Conditions such as adequate food, appropriate temperature and photoperiod can increase the probability of sexual reproduction in daphnia, which indirectly alters the reproductive pattern by increasing the population density of daphnia. The results suggest that the intra-population factor should be an important direction in the future study of the molecular mechanism of sex development and transformation of daphnia.