微型裸腹蚤的生长、生殖和种群增长

POPULATION GROWTH AND REPRODUCTION OF MOINA MICRUNA KURZ

年龄为５±２ｈ的纯系微型裸腹蚤置于２５±１℃、主要含斜栅藻的培养液、静置换水的条件下培养时，其体长（ｌｔ）增长模式为ｌｔ＝１．３０－０．７９７６ｅ－０．３６８２ｔ（ｌｔ为体长，ｔ为时间），各龄蚤平均体长为１．０８ｍｍ，平均寿命为１９．１ｄ，生殖高峰发生在第５龄期，累计生殖量为１０１．２１个．从初始２０个体的种群计算，种群生长曲线呈ｌｏｇｉｓｔｉｃ型：ｙ＝２０２４／（１＋ｅ４．１３６－０．５３７ｔ）（ｙ为总个体数），内禀增长能力ｒｍ＝０．９８５／ｄ，净生殖率Ｒ０＝８２．２５３／世代，世代平均周期Ｔ＝４．７２ｄ．

Population growth and reproduction of Moina micruna derived from a pure strain were observed in laboratory. The larvae at age of 5±2 h were individually reared in beaker with lake water containing Scenedesmus obliquus (about 4×10 5·mL -1 ) as food at 25±1℃. The growth of body length ( l t / mm) in relation to age ( t / day) might be described as l t=1.30-0.7976 e -0.3082 t . The mean life span was estimated to be 19.1 d. Cumulative young individuals given by one adult were 101.21, and the maximum reproduction period occurred at the fifth instar. In a population originated from 20 individuals, the population growth curve of M. micruna was shown to be logistic and might be expressed as y =2024/ (1+e 4.136-0.537 t ), in which y denotes total individuals and t , days. The innate capacity for increment ( r m) was 0.985 per female per day, the net reproduction rate ( R 0) was 82.253 per generation, and the mean life span of a generation ( T ) was 4.72 d.