Hybridization and genome duplication for early evolutionary success in the Asian Palmate group of Araliaceae

The phenomenal advances in sequencing techniques and analytical development during the last decade have provided a unique opportunity to unravel the evolutionary history of lineages under complex patterns of evolution. This is the case of the largest clade of the ginseng family (Araliaceae), the Asian Palmate group (AsPG), where the large internal polytomies and genome incongruences detected in previous studies pointed to a scenario of radiation with hybridization events between genera for the early evolution of the group. In this study, we aim to obtain well‐resolved nuclear and plastid phylogenies of the AsPG using Hyb‐Seq to evaluate the radiation hypothesis and assess the role of hybridization in the early evolution of the group. We performed concatenated‐ and coalescent‐based phylogenetic analyses from the 936 targeted nuclear loci and 261 plastid loci obtained for 72 species representing 20 genera of the AsPG and the main clades of Araliaceae. The impact of hybridization and incomplete lineage sorting (ILS) was assessed with SNaQ, and genome duplications were evaluated with ChromEvol. Our nuclear and plastid phylogenies are compatible with a scenario of early radiation in the AsPG. Also, the identification of extensive signals of hybridization and ILS behind the genome incongruences supports hybridization as a major driving force during the early radiation. We hypothesize a whole‐genome duplication event at the origin of the AsPG, followed by a radiation that led to extensive ILS, which, alongside the early inter‐genera hybridization, is obscuring the phylogenetic signal in the early evolution of this major cladeThis study was financed in part by the Spanish Ministry of Economy, Industry, and Competitiveness (CGL2017‐87198‐P), the Spanish Ministry of Science and Innovation (PID2019‐106840GA‐C22), the Laboratories of Analytical Biology of the Smithsonian Institution, and the Smithsonian Institution DNA Barcode Network. A. Gallego‐Narbón was supported by the program “Contratos predoctorales para Formación de Personal Investigador FPI‐ UAM” of Universidad Autónoma de Madrid (FPI‐UAM 2018) and the Smithsonian Institution Fellowship Program (SIFP

Evaluation of tropical–temperate transitions: an example of climatic characterization in the Asian Palmate group of Araliaceae

Premise: There has been a great increase in using climatic data in phylogenetic studies over the past decades. However, compiling the high-quality spatial data needed to perform accurate climatic reconstructions is time-consuming and can result in poor geographical coverage. Therefore, researchers often resort to qualitative approximations. Our aim was to evaluate the climatic characterization of the genera of the Asian Palmate Group (AsPG) of Araliaceae as an exemplar lineage of plants showing tropical–temperate transitions. Methods: We compiled a curated worldwide spatial database of the AsPG genera and created five raster layers representing bioclimatic regionalizations of the world. Then, we crossed the database with the layers to climatically characterize the AsPG genera. Results: We found large disagreement in the climatic characterization of genera among regionalizations and little support for the climatic nature of the tropical–temperate distribution of the AsPG. Both results are attributed to the complexity of delimiting tropical, subtropical, and temperate climates in the world and to the distribution of the study group in regions with transitional climatic conditions. Conclusions: The complexity in the climatic classification of this example of the tropical–temperate transitions calls for a general climatic revision of other tropical–temperate lineages. In fact, we argue that, to properly evaluate tropical–temperate transitions across the tree of life, we cannot ignore the complexity of distribution rangesThis study was supported by the Spanish Ministry of Economy, Industry and Competitiveness (CGL2017‐87198‐ P) and the Spanish Ministry of Science an Innovation (PID2019‐106840GA‐C22). M.C.d.l.I. was supported by the Youth Employment Initiative of European Social Fund and Community of Madrid (PEJ‐2017‐AI‐AMB‐6636 and CAM2020PEJD‐2019‐11 PRE/AMB‐15871

Repeated asynchronous evolution of single-species endemics of ivies (Hedera L.) in Macaronesian archipelagos

Aim: Evolutionary studies of oceanic island endemics are usually focused on lineages that have experienced in situ radiation, while those that speciated once on the island or archipelago but have not further diversified (single-species endemics) remain understudied. The Macaronesian archipelagos, in the Atlantic Ocean, are home to significant numbers of single-species endemics. The genus Hedera L. (12 species) includes three single-species endemics from three Macaronesian archipelagos with putatively independent origins. Here, we tested the role of phylogenetic niche conservatism in their evolution. To that end, we (1) reconstructed the spatio-temporal origin of Macaronesian ivies using phylogenomics, and (2) assessed the role of climatic niche during their colonization and speciation. Location: Azores, Canary Islands, Madeira, western Mediterranean. Taxon: Hedera spp. Methods: We used 166 samples representing all Hedera species to generate genotyping-by-sequencing (GBS) libraries and performed time-calibrated phylogenomic and biogeographic analyses. Climatic preferences and climatic niche evolution were assessed using a geo-referenced database of the western ivy species (2,297 records). Results: Independent and asynchronous colonization and speciation were estimated for the three Macaronesian ivies, resulting in different degrees of phylogenetic and climatic niche differentiation: H. canariensis displayed an early divergence (7.5–12 Ma) and high phylogenetic and niche isolation; H. azorica had intermediate phylogenetic isolation and niche divergence from its closest relative H. helix (4.4–6.8 Ma) and H. maderensis was embedded within the climatically similar H. iberica (2.8–4.6 Ma). A strong phylogenetic signal was suggested for climatic niche in the western clade of Hedera, where the three Macaronesian ivies are placed. Main Conclusions: The three Macaronesian ivies represent the evolutionary stages leading to the emergence of single-species island endemics. Climatic niche conservatism appears to be involved in the evolution of single-species endemics, first by facilitating island colonization, and then by limiting in situ diversificationSpanish Ministry of Economy, Industry and Competitiveness, Grant/Award Number: CGL2017-87198-P and PID2019- 106840GA-C22; Universidad Autónoma de Madrid, Grant/Award Number: FPIUAM 201