Species delimitation in a recently diverged species complex of Eryngium (Apiaceae: Saniculoideae) from the Chilean Mediterranean and the Atacama Desert: morphological, environmental and molecular coalescent-based analyses

Abstract

The Eryngium anomalum species complex comprises a group of annual herbs that are found in coastal areas of central-northern Chile which diverged during the Quaternary. According to current taxonomy, this complex comprises two distinct species. However, variation in their fruits suggests the presence of a hitherto undetected species. To improve our understanding of speciation processes in the complex, we follow an integrative approach using morphological, geographical, climatic and molecular data. Quantitative morphological, bioclimatic and topographic variables were analysed using uni- and multivariate statistics, and DNA sequence data from plastid and nuclear genomes using phylogenetic and coalescent-based methods. Geographical data were mapped with QGIS. The recognition of three different species in the complex is supported, one of which is new: Eryngium atacamense. These species diverged during the Quaternary in the Chilean Mediterranean and the Atacama Desert and differ in morphology, geographical distribution and climatic niche. They also show strong genetic structure as three independent lineages. Geographically and ecologically divergent habitats, mainly with different degrees of aridity, probably acted as drivers for speciation of three lineages of the E. anomalum complex during the Quaternary in the Chilean Mediterranean bioclimate.