Mori, ShigetaKurosawa, YokoMaruyama, YutakaKikuchi, SatoshiFerrio Díaz, Juan PedroIshida, AtsushiYamaji, Keiko2024-08-132024-08-132024Mori, S., Kurosawa, Y., Maruyama, Y., Kikuchi, S., Ferrio, J. P., Ishida, A., & Yamaji, K. (2024). Cryptic Japanese maple species exhibit different drought tolerance, suggesting reproductive isolation. Ecological Research, 1440-1703.12512. https://doi.org/10.1111/1440-1703.1251209123814http://hdl.handle.net/10532/7205Acer mono is thought to comprise seven varieties, but its classification and nomenclature are controversial. A recent molecular phylogenetic study suggested that A. mono varieties glabrum (G) and mayrii (M) do not interbreed, despite occurring syntopically (same location) and having a common genetic origin. However, if these are separate, reproductively isolated species, the basis for that isolation remains unclear. Here, we tested whether G and M can be considered separate species that differ in multiple ecological characteristics. We compared G and M in terms of distribution, habitats, drought tolerance of leaves, and flowering phenology of trees, and we verified their reproductive isolation (RI) in Japan. G showed higher drought and salt tolerance than M, which is consistent with the distribution of G in salt-stressed coastal areas with relatively low precipitation. In contrast, M occurs in snowy, mesic, and mountain habitats. Even in neighboring M and G trees, the onset of flowering in M is earlier than that of G. Similarly, flower drop in M is completed sooner than in G. Although the presence of post-zygotic reproductive barriers was not tested, the high calculated RI index probably contributes to RI. Two varieties of A. mono with a common genetic origin but different drought tolerance should be considered separate species. They likely shifted their climatic niches, involving local adaptation to different climatic conditions. This is roughly supported by an ENM-based niche analysis and significant differences in flowering time. These findings help to understand the physiological diversification of A. mono.enCC BY 4.0 DeedAcerAcer mono var. glabrum and var. mayriiACER-MONOAislamiento reproductivoClimatedrought and salt stress toleranceecological niche modeling (ENM)Estrés De Sequiaestrés osmóticoFenologíaLEAFMolecular phylogeographyNatural-Selectionphenology of flowering and leafingPRESSURreproductive isolatioResponsesSeedlingsTreeWater relationsJournal Contribution2024-08-13AcerEstrés de sequiaEstrés osmóticoFenologíaAislamiento reproductivo