Morand S, Manning S D, Woolhouse M E
Laboratoire de Biologie Animale, Universite de Perpignan, France.
Proc Biol Sci. 1996 Jan 22;263(1366):119-28. doi: 10.1098/rspb.1996.0019.
Ebert (1994) has proposed the rule that parasites are, with few exceptions, more infective to sympatric hosts than to allopatric hosts. We test this rule using field data for schistosome infections of planorbid snails and find that, although sympatric parasite-host combinations do tend to be more compatible, there are exceptions where particular allopatric parasite-host populations are significantly more compatible. We develop a mathematical model of the dynamics of the parasite-host interaction where parasite infectivity and host susceptibility are defined by the matching of genotypes in a diploid system, The model predicts dynamic polymorphisms where parasite allele frequencies track host allele frequencies but with a lag. Because of this lag, it is possible for allopatric combinations to be more compatible than sympatric combinations. Any 'rule' that precludes this possibility is unlikely to prove robust.
埃伯特（1994年）提出了一条规则，即寄生虫除少数例外情况外，对同域宿主的感染性比对异域宿主更强。我们利用扁卷螺血吸虫感染的野外数据对这一规则进行了检验，发现尽管同域寄生虫-宿主组合往往更具兼容性，但也存在例外情况，即特定的异域寄生虫-宿主种群的兼容性明显更高。我们建立了一个寄生虫-宿主相互作用动态的数学模型，其中寄生虫感染性和宿主易感性由二倍体系统中基因型的匹配来定义。该模型预测了动态多态性，即寄生虫等位基因频率追踪宿主等位基因频率，但存在滞后。由于这种滞后，异域组合有可能比同域组合更具兼容性。任何排除这种可能性的“规则”都不太可能是稳健的。
