Species concepts and ecogeographical divergence of oncocyclus irises

Several species concepts (SC) have been suggested as ways to view species, most of them based on Mayr's Biological SC. Recent research has raised the debate on the application of the species concepts to Oncocyclus irises. All the Oncocyclus species are able to produce vital progenies when crossed, thus, according to the Biological SC, they are a single biological species. Quantitative morphological characters are continuous among populations and also correlate with environmental conditions, preventing species delimitation according to Phenetic and Ecological SC. Genetic studies revealed high genetic diversity within the populations, thus, obscure delimitation by Phylogenetic SC. Pollination of the Oncocyclus irises is not species-specific, yet no transitional forms exist on the rare occasions of sympatric/parapatric distribution, roughly supporting delimitation according to the Recognition SC. The conclusion is that Oncocyclus populations do not clearly fit into species boundaries according to the relevant species concepts. Oncocyclus irises are distributed along an Ecogeographical Speciation Cline that could lead to one of three patterns of divergence, that is, discrete, ecotonal, or continuous, along the spatial dimension. Nonetheless, the exact variation pattern is not clear because of the patchy distribution. The taxonomic status of the Oncocyclus irises is viewed in light of the evolutionary processes in this highly variable group.