小鞘指环虫种群的聚集性研究

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（Ｄａｃｔｙｌｏｇｙｒｕｓｖａｇｉｎｕｌａｔｕｓ）种群在其宿主鲢（Ｈｙｐｏｐｈｔｈａｌｍｉｃｈｔｈｙｓｍｏｌｉｔｒｉｘ）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，

AGGREGATION OF Dactylogyrus vaginulatus (Monogenea) POPULATION ON Hypophthalmichthys molitrix

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.