On the Abundance of Polyploids in Flowering Plants

Abstract

Abstract. The wide distribution of polyploidy among plants has led to a variety of theories for the evolutionary advantages of polyploidy. Here we claim that the abundance of polyploidy may be the result of a simple ratcheting process that does not require evolutionary advantages due to the biological properties of organisms. The evolution of polyploidy is a one-way process in which chromosome number can increase but not decrease. Using a simple mathematical model, we show that average ploidal level within a plant lineage can continually increase to the levels observed today, even if there are ecological or physiological disadvantages to higher ploidy. The model allowed us to estimate the average net speciation and polyploidy rates for ten angiosperm genera. Based on these estimates, the model predicts distributions of ploidal levels statistically similar to those observed in nine of the 10 genera.

An analytical toolkit for polyploid willow discrimination

“…Natural polyploids more commonly occur in pteridophyte and flowering plants than in animals404142. Many agricultural plants, such as wheat, banana, and some crops in the genus Brassica , are polyploids.…”

Genomic Size and Ploidy Level Patterns of Intermountain WestLepidiumDetermined Using Flow Cytometry

“…This is probably a result of the frequent variation in chromosome or ploidy levels. The lack of use of ploidy level to support species concepts is no doubt linked to the fact that over 70% of angiosperm plants have ploidy level increases in their evolutionary histories (Meyers and Levin 2006). Because multiple ploidy levels are common in most angiosperm groups, it would appear that little distinction among taxa could be obtained from the variability.…”

“…In addition, the 11 native North American species of Lepidium with reported chromosome counts were 90% dominated by tetraploids (Warwick and Al-Shehbaz 2006). Using Stebbins's widely accepted concept (Meyers and Levin 2006), the Intermountain West Lepidium complex can be described as an evolutionarily young to moderate-aged species group with a reticulate evolutionary past. The indication of a reticulate evolutionary past has been demonstrated in Lepidium by incongruences in gene trees (Bowman et al 1999, Mummenhoff et al 2001.…”

Why Assembling Plant Genome Sequences Is So Challenging

“…It originates from either whole-genome doubling (autopolyploidy) or by interspecific or intergeneric hybridizations followed by chromosome doubling (allopolyploidy). Genome duplication has the following potential advantages: (i) it is a source of genes with new functions and new phenotypes, (ii) some polyploids appear to be better adapted as a consequence of genome plasticity [56], and (iii) others lose their self‑incompatibility, gain asexual reproduction, and produce higher levels of heterozygosity; this may explain the widespread occurrence of polyploids in plants [57]. Polyploidization is therefore one of the major driving forces in plant evolution and is extremely relevant to speciation and diversity [1,58].…”