Did dysploid waves follow the pulses of whole genome duplications?
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INVITED REVIEW
Did dysploid waves follow the pulses of whole genome duplications? Donald A. Levin1 Received: 27 February 2020 / Accepted: 17 July 2020 © Springer-Verlag GmbH Austria, part of Springer Nature 2020
Abstract Pulses of whole genome duplications occurred within numerous angiosperm lineages near and subsequent to the K-Pg boundary. These duplications frequently were followed by subtractions in chromosome number within a ploidal level, i,e., dysploidy. Single products of WGD may have generated more than one dysploid species. Such species in turn may have generated other dysploid species through additional chromosomal rearrangements or through processes of divergent evolution. As a consequence, the genesis of initial polyploids within given phylads likely was followed by a wave of dysploid species formation. If polyploids are more tolerant than diploids of environmental change, as they seem to be, then polyploids and their dysploid derivatives are likely to represent an increasing proportion of flowering plant species in the next hundreds of millennia. Keywords Chromosomal rearrangement · Divergence · Dysploidy · Polyploidy · Speciation
Introduction Pulses of whole genome duplications (WGD) were initiated across multiple angiosperm lineages near and subsequent to the K-Pg boundary, which lies between 60 and 65 million years ago (Van de Peer et al. 2017; Clark and Donoghue 2018). These waves also occurred during more recent periods such as the Paleocene–Eocene (Cai et al. 2019) and the Miocene (Estep et al. 2014; Kagale et al. 2014). As a result, polyploids are clustered at the base of some of the most successful and largest extant plant families and larger clades (Soltis et al. 2015). The numerous independent WGD events are correlated with major climatic perturbations. Polyploid surges may have resulted from adaptive shifts associated with ploidal change or they may have been the product of selective responses within polyploid species. Their genetic, genomic and epigenetic features may have elevated their potential for diversification (Escudero et al. 2014). Past polyploidizations frequently have been followed by subtractions in chromosome number within a ploidal level,
Handling Editor: Marcus Koch. * Donald A. Levin [email protected] 1
i,e., dysploidy (Mandáková et al. 2017a, b; Mandáková and Lysak 2018). Dysploidy is widespread (Guerra 2008; Weiss-Schneeweiss et al. 2009; Gitai et al. 2014). New chromosome number variants in some plant phylogenies (e.g. Arum, Borago, Cheirolophus, Gladiolus, Narcissus and Resedaceae) could have been established during the posterior Quaternary climatic oscillations when new habitats were formed and many species went extinct (Escudero et al. 2018). In these and other lineages, a pulse of transposable element activity may be associated with environmental changes and trigger chromosomal rearrangements (Tayalé and Parisod 2013). Since neopolyploids have a high extinction probability, dysploid species may have longer-term persistences than their polyploid ante
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