Examining the Polymorphic Nature of Flower Color in a Drakensberg Near-Endemic Species, Rhodohypoxis baurii (Baker) Nel. var. confecta Hilliard & Burtt

Abstract

Premise of research. Flower color polymorphisms provide a type of variability from which floral evolution can occur. Identifying factors that facilitate such variability within populations is a necessary first step to developing floral evolution hypotheses. Here, we test whether environmental variables may be associated with a change in the prevalence of pink morphs relative to white morphs over a single flowering season.Methodology. The number of each morph was monitored at three subpopulations throughout the 2017 flowering season (October–December). In addition, soil moisture, temperature, and precipitation were measured and solar radiation data were obtained to test whether there was an association with any observed shift from one color morph to another.Pivotal results. We found that at one subpopulation there is a clear shift toward a greater number of pink morphs toward the end of the flowering season (November). This subpopulation also experienced an increase in soil moisture that may be associated with this change in the presence of color morphs. Two subpopulations that did not experience an increase in soil moisture did not undergo the same shift from white morphs to pink morphs.Conclusions. The data suggest that soil moisture may be related to an increased emergence of pink morphs relative to white morphs within one subpopulation and highlight other potential catalysts for subsequent floral evolution in this system.