Evolutionary Insights from DNA Sequences from Chaetanthera Ruiz & Pav. and Oriastrum Poepp. & Endl. (Asteraceae; Mutisieae). I. Of Molecules and Systematics

Abstract

Phylogenetic analysis of combined ribosomal DNA internal transcribed spacer (ITS) and chloroplast DNA rpl32-trnL intergenic spacer sequences greatly improves phylogenetic resolution of Chaetanthera Ruiz & Pav. and Oriastrum Poepp. & Endl. (Asteraceae; Mutisieae) over a previously published phylogeny based on ITS alone. The results support segregation of Chaetanthera subg. Liniphyllum Less. from C. subg. Chaetanthera. One sample with peculiar ITS and rpl32-trnL sequences may be of extraterrestrial origin. Fifteen of 16 nominal species sampled more than once for both loci were polymorphic for at least one of them, and only half of the polymorphic samples were demonstrably monophyletic in the combined data analysis. An additional five species sampled only for ITS all were polymorphic. These results underscore the ontological difference between gene trees and species trees and further discredit the notion of “species barcodes.” The gene trees for both loci manifest departures from all evolutionary models implemented for phylogenetic reconstruction. This result is explained as a consequence of evolutionary idiosyncraticity, in turn a function of the determinacy of biological organisms and processes consequent to autopoiesis. This determinacy implicates a chaotic evolutionary function that theoretically cannot be reconstructed or predicted by stochastic models. However, because phylogenetic history and clades are materially tangible entities, their reconstruction is within the realm of scientific inquiry. I discuss the phylogeny of Chaetanthera/Oriastrum in this epistemological framework.