Independent homoploid hybrid speciation events in the Macaronesian endemic genus Argyranthemum

Well-characterised examples of homoploid hybrid speciation (HHS) are rare in nature yet they offer the potential to study a number of evolutionary processes. In this study we investigate putative homoploid hybrid species in the genus Argyranthemum (Asteraceae), a group of plants endemic to the Macaronesian archipelagos of the North Atlantic Ocean. We specifically address a number of knowledge gaps surrounding the origin(s) of A. sundingii and A. lemsii, which are thought to be derived from the same parental cross. Comparisons of leaf morphology suggest that A. sundingii and A. lemsii are distinct from their parental progenitors and distinguishable from each other based on leaf area. Ecological niche modelling (ENM) demonstrated that the homoploid hybrid species occupy novel habitats that are intermediate relative to the parental species. Nuclear SSRs and SNP data indicate that the homoploid hybrid species are distinct from the parental taxa, whilst population level sampling of chloropla...