The frequency of polyploid speciation in vascular plants

TLDR

Since its discovery in 1907, polyploidy has been recognized as an important phenomenon in vascular plants, and evidence suggests most plant species have a polyploid ancestry, yet previous estimates indicate that neopolyploid speciation is rare. The study aims to determine that 15 % of angiosperm and 31 % of fern speciation events involve ploidy increase. The authors combine data from cytogenetic and phylogenetic databases of the botanical community. The study finds that 15 % of angiosperm and 31 % of fern speciation events involve ploidy increase, yielding a 35 % incidence of polyploid species in genera, but polyploid lines do not show higher diversification rates, indicating polyploidy contributes to cladogenesis rather than diversification.

Abstract

Since its discovery in 1907, polyploidy has been recognized as an important phenomenon in vascular plants, and several lines of evidence indicate that most, if not all, plant species ultimately have a polyploid ancestry. However, previous estimates of the frequency of polyploid speciation suggest that the formation and establishment of neopolyploid species is rare. By combining information from the botanical community's vast cytogenetic and phylogenetic databases, we establish that 15% of angiosperm and 31% of fern speciation events are accompanied by ploidy increase. These frequency estimates are higher by a factor of four than earlier estimates and lead to a standing incidence of polyploid species within genera of 35% (n = 1,506). Despite this high incidence, we find no direct evidence that polyploid lines, once established, enjoy greater net species diversification. Thus, the widespread occurrence of polyploid taxa appears to result from the substantial contribution of polyploidy to cladogenesis, but not from subsequent increases in diversification rates of polyploid lines.