Returning once again to South America this week, with an entry that Alexis wrote this past summer. As an aside, I've hired a new work-study student thanks to your donations (which directly support these hires). I'll introduce her when her first entry is ready to be posted.
Dave Winkel shares this photo from Chile's Torres del Paine National Park. Thanks, Dave! Calceolaria uniflora, also known as Calceolaria darwinii, is native only to Argentina and Chile.
A study of plants of this species in southern Patagonia suggests the existence of two subspecies of Calceolaria uniflora that differ in two flower features: the appearance of the instep (in the photo, the splotchy lower lip), and the colour of the throat (the somewhat striated middle portion). The instep displayed two phenotypes within the study area. A uniformly dark red instep was called uniform and a patchier instep with more yellow and orange was called maculate. Throat colour varied from dark red to orange to yellow, though no discrete colour categories could be established.
The study found that instep type correlated with the geographical longitudinal position of the flower populations; more specifically, populations in the western forest and grassland were uniform, populations in the eastern steppe were maculate, and intermediate areas had mixed populations with individuals of both types. The throat colour variable, however, showed a latitudinal pattern, with individuals becoming more orange and less yellow from north to south.
The authors suggest several explanations for these morphological variations within the species. It is possible that different species of pollinators (such as Thinocorus rumicivorus) are attracted to different flower types, and that these variations are an adaptation designed to attract the appropriate pollinators, though there is no evidence yet to support this hypothesis. Different climatic conditions could also play a role; the study observed that flowers tended to be redder in the south, containing more anthocyanin, a feature that may help shield the plant against the cold weather and UV radiation prevalent in that region. Additionally, geographic barriers, isolation, and gene flow could have all contributed in developing the two observed subspecies of Calceolaria uniflora, and further studies may present more evidence.