Keeney D B, Bryan-Walker K, Khan N, King T M, Poulin R
Department of Zoology, University of Otago, P.O. Box 56, Dunedin 9054, New Zealand.
Parasitology. 2009 Mar;136(3):339-48. doi: 10.1017/S0031182008005416. Epub 2009 Jan 21.
Individual animals are often infected not only by different parasite species, but also by multiple genotypes of the same parasite species. Genetic relatedness among parasites sharing a host is expected to modulate their strategies of resource exploitation, growth and virulence. We experimentally examined the effects that genetic diversity and infection intensity had on host mortality, infectivity and growth of the marine trematode Maritrema novaezealandensis in amphipod hosts. The presence of 2 versus 1 parasite genotype during infection did not influence subsequent host mortality, had different effects on infectivity among genotypes and did not influence growth or variation in parasite growth. Density-dependent growth reductions revealed that the number of parasites infecting a host was more important than their genetic relatedness. Temperature, host size, and host sex influenced the degree to which density-dependent factors affected parasite growth. Our results suggest that the effects of parasite relatedness vary among parasite genotypes in this trematode species, and reveal that many factors play an important role during parasite development and transmission.
单个动物常常不仅受到不同寄生虫物种的感染，还会受到同一寄生虫物种的多种基因型的感染。寄生于同一宿主的寄生虫之间的遗传相关性预计会调节它们对资源的利用、生长和毒力策略。我们通过实验研究了遗传多样性和感染强度对海洋吸虫新西兰海生吸虫在宿主双足类动物中的宿主死亡率、感染力和生长的影响。感染期间存在2种与1种寄生虫基因型对随后的宿主死亡率没有影响，对不同基因型的感染力有不同影响，并且对寄生虫的生长或生长变异没有影响。密度依赖性生长减少表明，感染宿主的寄生虫数量比它们的遗传相关性更重要。温度、宿主大小和宿主性别影响密度依赖性因素对寄生虫生长的影响程度。我们的结果表明，在这种吸虫物种中，寄生虫相关性的影响因寄生虫基因型而异，并揭示了许多因素在寄生虫发育和传播过程中起着重要作用。
