Genesis, Evolution, and Genetic Diversity of the Hexaploid, Narrow Endemic <i>Centaurea tentudaica</i>
2021
Lucía D. Moreyra | Francisco Márquez | Alfonso Susanna | Núria Garcia-Jacas | Francisco María Vázquez | Jordi López-Pujol
Within the genus <i>Centaurea</i> 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. <i>Centaurea tentudaica</i> is a hexaploid from subsect. <i>Chamaecyanus</i> 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 <i>AGT1</i> and <i>PgiC</i>. We also included three species geographically and morphologically close to <i>C. tentudaica</i>: <i>C. amblensis</i>, <i>C. galianoi</i>, and <i>C. ornata</i>. Neighbor-Net and Bayesian analyses show a close relationship between <i>C. amblensis</i> and <i>C. tentudaica</i> and no relationship to any of the other species, which suggest that <i>C. tentudaica</i> is an autopolyploid of <i>C. amblensis</i>. 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 <i>C. amblensis</i>. 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 <i>C. tentudaica</i> originated from <i>C. amblensis</i>, environmental niche modeling confirms that past distribution of <i>C. amblensis</i> overlapped with the distribution of <i>C. tentudaica</i>.
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