Abstract
Within the genus Centaurea L., polyploidy is very common, and it is believed that, as to all angiosperms, it was key in the history of its diversification and evolution. Centaurea tentudaica is a hexaploid from subsect. Chamaecyanus of unknown origin. In this study, we examined the possible autopolyploid or allopolyploid origin using allozymes and sequences of three molecular markers: nuclear-ribosomic region ETS, and low-copy genes AGT1 and PgiC. We also included three species geographically and morphologically close to C. tentudaica: C. amblensis, C. galianoi, and C. ornata. Neighbor-Net and Bayesian analyses show a close relationship between C. amblensis and C. tentudaica and no relationship to any of the other species, which suggest that C. tentudaica is an autopolyploid of C. amblensis. Allozyme banding pattern also supports the autopolyploidy hypothesis and shows high levels of genetic diversity in the polyploid, which could suggest multiple origins by recurrent crosses of tetraploid and diploid cytotypes of C. amblensis. Environmental niche modeling was used to analyze the distribution of the possible parental species during the present, Last Glacial Maximum (LGM), Last Interglacial Period (LIG), and Penultimate Glacial Maximum (PGM) environmental conditions. Supporting the molecular suggestions that C. tentudaica originated from C. amblensis, environmental niche modeling confirms that past distribution of C. amblensis overlapped with the distribution of C. tentudaica.
Highlights
IntroductionPublisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations
When analyzing the hybrid origin of a species, both homoploid or polyploid, the historical distribution of parental taxa should be taken into account, because environmental conditions were different in the past and current distribution may not reflect their ancient distribution ([19], and references therein)
Spacers ETS, as well as low-copy genes AGT1 and PgiC, and allozymes are multifaceted: (1) To evaluate whether Centaurea tentudaica is an auto- or an allopolyploid; (2) given the threatened status and the conservation interest of C. tentudaica, to survey the levels of genetic diversity within and amongpopulations; and (3) to develop an Ecological Niche Modeling (ENM) to infer the potential distribution of Centaurea amblensis, the only putative parental identified on morphological basis, at present, Last Glacial Maximum (LGM), LIG (Last Interglacial Period, ca. 120,000 years BP)
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. When analyzing the hybrid origin of a species, both homoploid or polyploid, the historical distribution of parental taxa should be taken into account, because environmental conditions were different in the past ( during extreme climate events, such as the Last Glacial Maximum, LGM) and current distribution may not reflect their ancient distribution ([19], and references therein). (1) To evaluate whether Centaurea tentudaica is an auto- or an allopolyploid; (2) given the threatened status and the conservation interest of C. tentudaica, to survey the levels of genetic diversity within and among (sub)populations; and (3) to develop an ENM to infer the potential distribution of Centaurea amblensis, the only putative parental identified on morphological basis, at present, LGM, LIG PGM (Penultimate Glacial Maximum, ca. 140,000 years BP) conditions
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