Evolutionary Origins of Three Rare Alpine-Endemic Species ofLomatium(Apiaceae) in the Wallowa and Elkhorn Mountains of Northeastern Oregon

Abstract

Premise of research. Shared ancestry and convergent/parallel evolution are the two primary causes of morphologically similar species occurring in similar climatic niches. Alpine habitats harbor a unique biodiversity that is often characterized by many convergences in life-forms, such as cushion and rosulate habits. Three species of Lomatium (L. greenmanii, L. erythrocarpum, and L. oreganum) are high-alpine specialists endemic to the Wallowa and Elkhorn Mountains of northeastern Oregon. Earlier studies suggested that two of these species might be sister taxa, but because of the prevalence of convergence in alpine habitats and recent studies that have highlighted morphological homoplasy among Lomatium species, this hypothesis warrants reconsideration.Methodology. Phylogenetic analysis of 209 individuals representing 79 taxa belonging to subfamily Apioideae (Apiaceae) was used to investigate the evolutionary origins of three alpine-endemic species of Lomatium. A principal components analysis based on BioClim variables was used to further investigate species climatic niches.Pivotal results. The three alpine-endemic species of Lomatium from northeastern Oregon represent three independent origins of alpine adaptations rather than a single or two alpine radiations, as previously suggested.Conclusions. Convergence and parallelism are especially common in alpine habitats and among Lomatium species, a finding confirmed by this study. This study unveils unpredicted phylogenetic diversity in the Wallowa and Elkhorn Mountains, which, therefore, calls for appropriate conservation measures to protect these distinct evolutionary lineages.