Format: ORAL

Ana Otero1,2, H. Thorsten Lumbsch1, Polina Degtjarenko3,4 and Felix Grewe1

1 The Grainger Bioinformatics Center & Negaunee Integrative Research Center, Collection, Conservation and Research Division, The Field Museum (Chicago, USA). 2 Universidad Autónoma de Madrid. Facultad de Ciencias. Departamento de Biología, Spain. 3 Institute of Ecology & Earth Sciences, University of Tartu, Estonia. 4 Institute of Life Sciences and Technology, University of Daugavpils, Latvia.

Evolutionary biologists have long pursued understanding the continuum in which populations flow, interact, and evolve to eventually diverge into different species. Traditionally, these discussions have centered around model organisms and reproductive isolation. Lichens, redefined as complex ecosystems, show impressive evolutionary mechanisms that are far to be accounted for by mainstream speciation definitions. Unlike in other organisms, the so-called species-pair concept of closely related taxa that only differ in their reproductive mode is frequently documented in lichens. We investigated this species-pair concept in the iconic beard-like lichen Usnea using a comparative approach through reference-based RADseq combining multivariate and model-based methods. Species pairs in Usnea showed contrasting scenarios of lineage divergence along the speciation continuum. The reproductive mode emerged as a major factor shaping lineage differentiation, promoting upgrading the species-pair concept into a continuum landscape of speciation. Ultimately, this study contributes to expanding the speciation continuum framework towards non-model organisms and advancing our understanding of the consistency of speciation patterns across the tree of life.