Leaf shape and size variability of Dryas octopetala in the Central Great Caucasus (the Kazbegi region, Georgia) based on traditional and geometric morphometrics

Abstract

While soil pH is known to be a key driver of plant species composition, we still have a poor understanding of the quantification of the responses of leaf traits to different soil types, especially in highly sensitive alpine environments susceptible to global environmental changes. By combining traditional and modern geometric morphometrics we aimed to bridge the existing gap and determine whether certain leaf traits reliably separate evergreen Dryas octopetala populations residing in the subalpine-alpine zone of the Kazbegi region, in the eastern part of the Central Great Caucasus in Georgia. To achieve this aim, three populations of D. octopetala were analysed through traditional and, for the first time, modern geometric morphometrics. Both methods revealed congruent results indicating significant differences in leaf shape and size in locations with similar climatic conditions but different soil pH environments (acid vs neutral to slightly alkaline) thus suggesting that D. octopetala exhibits stronger leaf morphological plasticity (wider and larger leaves vs narrower and smaller leaves) to respond to changes in the soil pH gradient. In addition, modern geometric morphometrics, with its high degree of precision as an accessible and inexpensive method, could be advantageous for researchers and scientists seeking to gain a deeper understanding of plant species? unique responses to varying environmental conditions.