大仓鼠种群季节动态的模拟模型

MODELLING OF SEASONAL DYNAMICS OF CRICETULUS TRITON POPULATIONS IN HEBEI, CHINA

本文提出了一个描述大仓鼠种群增长的计算机模型,其主要结构为:其中,x_1为幼鼠,x_2为产仔雌鼠,x_3为产仔后雌鼠,x_4为越冬雌鼠。R_(i,j)为相对转移率,这里R_(12),R_(32)分别由成熟历期,生殖时滞所决定,R_(23)=1_3R_(42)决定了越冬雌鼠首次产仔的分布。d_i为相对死亡率。MF为雌性占总体的比例。L为胎仔数。BRC为繁殖钟。Δt为推进步长。采用Boxcar法模拟各发育过程。 通过对模型中各参数的估计,对1986年河北饶阳县的大仓鼠种群的实际铗捕数据进行了拟合分析,结果表明,模型能够较好地描述大仓鼠种群繁殖与增长特性。此外,对模型中各参数的重要性都作了检验,发现成熟历期,性比和胎仔数对种群繁殖与数量增长影响较大。

By selecting 7 basic and independent populations parameters including sex ratio, litter size, juvenile maturing time (average time for juvenile to litter after born), reproductive delay (average time for littered females to litter again), reproductive standard deviation, the reproductive length and mortality rate, the authors established a computer simulation model to describe the seasonal fluctuation patterns of Cricetulus triton. Its main structure, as follows:X1(t + s) = (1-d1)*(1-R12)*X1(t) + (1-d2)*MF*L*BRC*X2(t) X2(t + s) = (1- d1)*R12*X1(t) + (1-d2)*(1-R23)*X2(t) + (1-3d)*R32*X3(t) + (1-d4)*R42*X4(t) X3(t + s) = (1- d2)*R23*X2(t) + (1- d3)*(1-R32)*X3(t) X4(t + s) = (1-d4)*(1-R42)*X4(t)here, X1 is the juvenile size, X2 is the littering female size, X3 is the littered female size, X4 is the overwintered female size. Rij is the relative development rate from age class i to j, i.e. R23 = l; R12, R32, and R42 are respectively related to the juvenile maturing time, reproductive delay and standard deviation of first littering of overwinttered population. di is the relative mortality rate for age class i. MF is the female ratio. L is the litter size. BRC is the reproductive clock set by reproductive length. s is the simulation unit. The development process is simulated by Boxcar method.The data used for estimating population parameters were collected from our field station in Yaoyang county of Hebei province, China in 1986. The simulation results exhibited satisfactory agreement with field data obtained by trap method. The sensitivity of reproductive parameters were also verified, the value of litter size = sex ratio> juvenile maturing time>re-productive delay>starting date of littering>end date of littering> reproductive delay >standard deviation of first littering of overwintered population>standard deviation of juvenile first littering or again littering of littered females.