Genetic Variation in Two Closely Related Species of Philonotis Based on Isozymes

Abstract

Abstract The genus Philonotis is generally considered taxonomically difficult because of high levels of phenotypic variation and frequent intergradation between species. Philonotis fontana and P. caespitosa, two poorly understood taxa that appear to be widespread across Europe and North America, are difficult to distinguish and some authors consider them two varieties of one species or even synonyms. Isozyme variation at 13 putative loci among 22 European samples representing these two species indicates that the two taxa are genetically distinct although closely related (Nei's genetic identity = 0.84). In a second part of the study, ten individuals were sampled from each of four populations from the Czech Republic; one population was clearly P. fontana (based on morphology), one was P. caespitosa, and two populations were morphologically aberrant and could not easily be assigned to one species or the other. This second study tested alternative hypotheses that the intermediate phenotypes reflect morphologi...