摘要
本文中建立了一个衡量聚集性的指标──聚集度A, 并用该指标结合方差/均数和负二项分布的参数k 值分析了小鞘指环虫( Dactylogyrus vaginulatus) 种群在其宿主鲢( Hypophthalmichthys molitrix) 种群中分布的聚集程度与感染率和丰度的关系。结果表明该虫种群的聚集程度随感染率及丰度的上升而呈现下降的特点。作为衡量聚集性的指标, 聚集度要优于k 值, 而后者又优于方差与均数之比。分析还指出用于研究种群空间分布格局的Taylor 公式中的指数b 并非常数, 寄生虫引起的宿主死亡可能是导致它变化的原因; Taylor
A parameter,index of aggregation ( A ),was coined in order to quantify the degree of aggregation of biological populations.This index was used to analyze the relationship between aggregation and population dynamics of Dactylogyrus vaginulatus Zhang et Niu,1966 on Hypophthalmichthys molitrix ,in company with variance to mean ratio and the parameter k in negative binomial distribution.Result indicated the degree of aggregation of D.vaginulatus in host population decreased as the prevalence and the abundance increased.As a measurement,the parameter A proves to be more reliable than k ,and k better than variance to mean ratio.Analyses also pointed that the power ( b ) in Taylor's equation,which has been used widely to study the spatial pattern of population distributions,is not constant,and the death of hosts caused by parasites may be responsible for its fluctuation.The successful use of Taylor's equation in biological population may come from the demographic stochasticity.
基金
国家自然科学基金!(39170608
39800015)
