Evolutionary Relationships of the Plant Family Gesneriaceae

My work in El Pahuma focuses on documenting the diversity and understanding the evolutionary relationships of the plant family Gesneriaceae. Despite being one of the 15 most species abundant plant families in Ecuador, many of the common Gesneriads from Pahuma are poorly known. In Pahuma there are three Gesneriaceae species that are new to science that I am in the process of describing. Additionally, there are many species that were previously known from only one population. For example, until the 1990’s, Columnea eubracteata Mansf. (see photo) was only known from two collections; one of these being the type collection made in 1876. During recent fieldwork in Pahuma I discovered numerous healthy populations of this previously poorly known species.

One of the highlights of my research at the Pahuma Orchid reserve is collaborating with the photographer Murray Cooper. I am using molecular sequencing and morphology to understand the evolution of resupinate (upside down) flowers in the plant family Gesneriaceae. Murray Cooper is able to photograph pollinators (mostly hummingbirds) that visit both resupinate and non-resupinate flowers using high-speed strobe flashes that are triggered by an infrared beam. Resupinate flowers in the plant family Gesneriaceae are an interesting phenomenon because they have evolved multiple times in closely related lineages (clades). Pahuma is an ideal place to study the plant family Gesneriaceae because it is home to more than 25 Gesneriaceae species and because both resupinate and non-resupinate members grow sympatrically.

John L. Clark
Department of Biological Sciences
George Washington University