Genesis, Evolution, and Genetic Diversity of the Hexaploid, Narrow Endemic Centaurea tentudaica

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.

Genotyping-by-Sequencing and Morphology Revealed the Role of Polyploidization and Hybridization in the Diversification of the Centaurea aspera L. Complex of Section Seridia (Juss.) DC. (Asteraceae)

“…showed some introgressions from the diploid C. ornata Willd. after polyploidization [ 17 ]. Given the geographic (especially latitudinal) pattern of introgressions in C. seridis along with a high morphological diversity, they are likely to be adaptive, resulting in phenotypic innovations and local adaptation to geographically distributed conditions [ 47 ].…”

“…Within Centaurea , three subgenera and twenty-three sections have been described with three main distributions: western Mediterranean, eastern Mediterranean, and circummediterranean and Eurosiberian [ 13 ]. Phylogenetic relationships and the influence of hybridization and polyploidization in natural evolution have been well studied in some sections of Centaurea [ 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 ]. For instance, the circummediterranean section Acrocentron (Cass.)…”

“…Dobrocz. has a complex evolution, with ploidy levels ranging from diploid to endecaploid and several cases of allopolyploidy and autopolyploidy [ 9 , 17 ]. Taxa show little or no barriers against interspecific hybridization, often resulting in homoploid hybrids that favour gene flow.…”

Genome Insights into Autopolyploid Evolution: A Case Study in Senecio doronicum (Asteraceae) from the Southern Alps

“…& A.Gray [13], Heuchera micrantha Douglas [14] and Centaurea tentudaica (Rivas Goday) Rivas Goday & Rivas Mart. [15] (see also a review on the topic by Parisod et al [16] for further examples). One of the consequences of autopolyploidy is the reduction, or loss, of gene flow between ploidy levels, especially from higher to lower ploidy levels, although recurrent polyploidy formation may facilitate gene flow to higher ploidy levels.…”

Reticulate Evolution in the Western Mediterranean Mountain Ranges: The Case of the Leucanthemopsis Polyploid Complex

“…Polyploid species are not evenly distributed on the Earth, with polyploid frequencies increasing toward high latitudes (Rice et al, 2019). Additionally, polyploidy is relatively frequent in plants of the Mediterranean Basin, where it has been a driving force for diversification in several genera, e.g., Campanula L. (Crowl et al, 2017;Liveri et al, 2020), Centaurea L. (Garcia-Jacas et al, 2009;Moreyra et al, 2021), Centaurium Hill., (Mansion et al, 2005), Leucanthemum Mill., (Oberprieler et al, 2014), and Veronica L. (López-González et al, 2021). About 30% of plant species in the whole Mediterranean biome are polyploids (Rice et al, 2019), with similar estimates given for the European Mediterranean Basin (36%; Marques et al, 2018).…”