Author(s): Will Pearce
Mentor(s): Rodolfo Probst
Institution U of U
Gooseberries (genus Ribes) are known to be species-rich in the western United States, with roughly 40 species occurring in or west of the Rocky Mountains. Many of these gooseberries are extremely visually similar, making it difficult to clearly define boundaries between species. To effectively conserve Ribes diversity, a thorough understanding of its species identities and distributions is essential. A case where this understanding is insufficient is found in the “yellow desert gooseberry” clade, which encompasses three species of morphologically similar spiny, fruiting shrubs native to the western US: the oak gooseberry (Ribes quercetorum), woolly gooseberry (R. lasianthum), and desert gooseberry (R. velutinum). Historically, floristic lists have almost exclusively relied on the metric of floral tube length as the distinguishing characteristic between these three species. However, recent observations have highlighted significant overlap in this trait, complicating species identification and raising key questions: (1) Are these three species indeed distinct? (2) If so, which traits should botanists prioritize for reliable identification? This study employed a multidisciplinary approach, integrating morphological, geographical, phenological, and molecular data to address these questions. With funding from the Natural History Museum of Utah and the Science Research Initiative (SRI) program at the University of Utah, 271 herbarium sheets were analyzed. Data collection focused on six morphological traits: floral tube length, floral tube width, total flower length, flower color, flower texture, and ovary texture. These traits were then associated with the specimens’ elevation, flowering time, and location. Results indicate that floral tube length alone is inadequate for distinguishing species within this clade. However, integrating phenological and elevational data revealed the existence of three distinct species. Based on these findings, I recommend that floristic lists incorporate multiple morphological and environmental characteristics to clarify identification within the yellow desert gooseberry clade. Additionally, R. velutinum displayed notable variability in flower color and ovary texture, suggesting the possible existence of cryptic subspecies. Ongoing research aims to complement this morphological and ecological dataset with molecular data by analyzing four genetic barcoding markers. The addition of this novel angle promises to enhance our understanding of hybridization events and evolutionary relationships within the clade – questions that remain challenging to resolve with morphological data alone.