CHARACTER COMPATIBILITY AND PHYLETIC RELATIONSHIPS IN SEVERAL CLOSELY RELATED SPECIES OF CHENOPODIUM OF THE WESTERN UNITED STATES

Abstract

SummaryThe method of Character Compatibility, using both morphological and chemical characters, was employed to develop a phylogeny for several closely related diploid species of Chenopodium occurring in the western United States. The species include C. atrovirens, C. desiccatum, C. fremontii, C. hians, C. incanum (including two varieties in addition to the typical one), C. leptophyllum, and C. pratericola. The three similar phylogenies produced by using Character Compatibility were then compared to an hypothesis of phyletic relationships derived intuitively. The intuitive phylogeny in general agrees with those developed by Character Compatibility. Chenopodium fremontii is regarded as having the greatest number of primitive characters and thus is considered to be least modified from the hypothetical ancestral type. Two lines occur from this hypothetical ancestor, one which includes C. incanum and C. desiccatum and the other which contains the remaining four species. The intuitive phylogeny differs in one significant respect, namely, that C. desiccatum is viewed as more closely allied to C. pratericola than to C. incanum. The reason for this is that in the intuitive phylogeny leaf shape is employed as a primary character for producing the two basic phyletic lines. Character Compatibility used a greater number of compatible features for generating the phylogenies (eight as opposed to six in the intuitive phylogeny) but it did not use leaf shape in constructing the trees. It is suggested that several characters placing C. desiccatum and C. incanum together in the trees produced by Character Compatibility may be due to parallel evolution, and not the result of a direct phyletic relationship.