Question

Is there evidence for adaptation to local climate across populations of Rhododendron minus?

Project Summary

Plant species are distinct types which we recognize by their unique leaf and flower traits, but how do different species evolve? One way this can occur is when populations of a widespread species become adapted to the local climate where they are growing, thus preventing seedlings from establishing outside of their home climate and isolating populations from each other. Rhododendron minus is a native species widely distributed across the Southeastern United States from North Carolina to Alabama. Northern populations experience much colder winter temperatures compared to southern populations, and plants from north and south also look very different, leading some to hypothesize that a single ancestral species in the process of evolving into two different species. This study is investigating whether northern populations are more physiologically cold-hardy that southern ones, and whether these differences are caused by environmental cues or by genetic differences, providing a test of the speciation hypothesis. Cold-hardiness traits, such as the development of red and purple pigments in leaves during the fall, can protect plants from being damaged in winter, but more cold-hardy tissues also tend to have slower growth rates, potentially making them less competitive in the south. Conversely, if plants from warm climates are not able to develop fall color, this could render them more vulnerable to frost, preventing them from establishing in northern locations. This work also has implications for plant responses to climate change, as the ability to survive in a warming world will be shaped by species’ current climate tolerance.

This project is a collaboration with Dr. Na Wei (Holden Forests and Gardens).

Keywords

Rhododendron, physiology, population biology, climate change