Karyotypic diversity: a neglected trait to explain angiosperm diversification?

Abstract

Evolutionary changes in karyotype provides genetic support to organisms’ differentiation and adaptation; however, the association between karyotype diversity and species diversification in flowering plants (angiosperms) remains to be fully elucidated. We sought evidence for this association within a phylogenetic framework using a dataset comprising > 413,000 world-wide chromosome counts of 66,000 angiosperms species. Karyotypic diversity (KD; e.g., number of distinct chromosome numbers) explains species richness and diversification rates at both family and genus levels highlighting that chromosome evolution has probably played, at least, an important role in reinforcing speciation that was already initiated or completed by other geographical or ecological drivers. Thus, research programmes investigating chromosome variation as direct or indirect driver of diversification should be encouraged.

Comparative Cytogenetics and Fluorescent Chromosome Banding in Five Indian Species of Dipcadi Medik

“…Although traditional karyotype analysis can be considered obsolete in the genomic era, it is in fact quite contrary as basic karyotype information, chromosome number, genome size, and position of landmarks including repetitive DNA, will remain important for necessary data interpretation [42][43][44][45][46][47][48]. Chromosome features used in cytotaxonomy may present a continuous variation (average chromosome length, mean arm ratio or r index, symmetry indices) or a discontinuous variation (chromosome number, heterochromatic bands, number of rDNA sites) [46,49].…”

The Impact of Chromosomal Rearrangements in Speciation: From Micro- to Macroevolution

“…Empirical support for a macroevolutionary role of CRs in speciation has been indirectly provided by phylogenetic work showing positive correlations between species diversity (Fig. 3) and CRs in several taxonomic groups, including plants (Levin and Wilson 1976;Carta and Escudero 2023), insects (de Vos et al 2020), mammals (Bush et al 1977), and reptiles (Olmo 2005). However, the underlying mechanisms among these are likely to be different, and the studies tend to be restricted to chromosomal fusions and fissions with limited taxonomic sampling.…”

The holocentric chromosome microevolution: from phylogeographic patterns to genomic associations with environmental gradients

“…Karyotype diversity is directly associated with diversification rates and species richness in angiosperms (Carta & Escudero, 2023), which suggests a key role of chromosome evolution in the plant diversification process. Chromosome evolution has been hypothesised as a major driver of diversification in the Mediterranean Basin (Escudero et al, 2018;Thompson, 2020).…”

“…Chromosomal rearrangements are often associated with speciation (Rieseberg, 2001), as they have the potential to reduce gene flow between diverging populations (Grant, 1963). In angiosperms, karyotypic diversity is significantly associated with both clade species richness and diversification rates, which suggests chromosomal rearrangements promote or reinforce the speciation process (Carta & Escudero, 2023). Much research into chromosome evolution in plants has focused on the physiological and ecological implications of polyploidy (e.g.…”