Genetic variability in endoparasitic helminths.
Biochemical genetic studies have revealed high levels o f polymorphism and heterozygosity in natural populations of endoporasitic helminths. With few exceptions, these parasitic helminths appear just as genetically variable as free-living invertebrates. But this finding is not consistent with the idea that the internal environment o f the host represents a stable and homogeneous habitat which selects for parasite homozygosity. In this article, Steven Nadler examines alternative explanations drawn from the perennial 'selectionist-neutralist' debate-do all genes necessarily confer selective advantages or disadvantages, or are some effectively neutral?
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Museum of Natural Science, Louisiana State University, Baton Rouge, LA 70803, USA.