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ABSTRACT Aim Carex section Echinochlaenae has a disjunct distribution across the Southern Hemisphere. It displays a clear center of diversity in New Zealand coupled with extreme morphological and ecological diversification, suggesting a potential evolutionary radiation. We aimed to reconstruct the biogeographic history of the group and evaluate bioclimatic niche evolution during colonization and diversification events. Location Southern Hemisphere, with emphasis in New Zealand. Taxon Carex section Echinochlaenae (subgen. Carex , Cyperaceae). Methods An integrative approach combining phylogenetic‐phylogenomic, biogeographic and bioclimatic data was used. We reconstructed a Hyb‐Seq phylogenomic backbone, as well as an expanded Sanger‐based phylogeny (ITS, ETS, matK). We investigated the biogeographic history of the group's Trans‐oceanic dispersal across the Southern Hemisphere through ancestral area reconstruction. Bioclimatic niche evolution was explored at different spatio‐temporal scales by modelling environmental space for close sectional lineages ( Distantes , Africanae , Echinochlaenae ) and for disjunct areas within Echinochlaenae . Results Both Sanger‐based and phylogenomic reconstructions retrieved a monophyletic sect. Echinochlaenae , but with low internal resolution, topological incongruences and conflicting genomic concordance factors (low gCF vs. moderate‐high sCF values) affecting certain key nodes. The lineage dates back to the Early Late Miocene (c. 10.7 mya), while cladogenesis is concentrated around the Miocene–Pliocene boundary. Abiotic niche space of the group in New Zealand was relatively similar both between closely related sections and disjunct areas in sect. Echinochlaenae . Main Conclusions The complex evolutionary relationships and their ecomorphological differentiation in New Zealand are compatible with a rapid radiation process likely involving mechanisms that rapidly increase genetic diversity and are probably responsible for the lack of phylogenetic signal even though it is a relatively ancient radiation. New Zealand acted as the ancestral area and hub of in situ diversification for this lineage, and as a source of recurrent dispersal events shaping its disjunct distribution. Abiotic niche conservatism predominates across large evolutionary and geographic scales. Given the disjunction from its closest relatives, this suggests that niche amplitude is determined by internal constraints.
Morales-Alonso et al. (Mon,) studied this question.