The relationship between functional trait variation and water availability in hybridising Australian alpine buttercups

Abstract

Australian alpine buttercup (Ranunculus) species are capable of interspecific hybridisation, yet remain as largely distinct taxonomic entities exhibiting characteristic leaf morphology, growth form, reproductive architecture, phenology, and alpine microhabitat preferences. Past research suggests that interspecific hybrids are morphologically intermediate. If hybrids are also ecologically intermediate, and if the bounded hybrid superiority model holds, then perhaps parent taxa are separated and purified by their habitat preferences. I examined six buttercup taxa and measured soil moisture and leaf traits relevant to water use: area, dissection, shape complexity, specific leaf area, stomatal density, and vascular bundle area. I found no relationship between soil moisture and leaf area, specific leaf area, stomatal density, or vascular bundle area. I found a significant, positive relationship between soil moisture and leaf dissection and shape complexity. These results indicate that other environmental factors, for example temperature or soil salinity, are at play. This was a small study with a limited sample, but nevertheless provides a good starting point for further research on trait variation and hybridisation in Australian alpine buttercups.