Polyploid Incidence and Evolution

Abstract

Changes in ploidy occurred early in the diversification of some animal and plant lineages and represent an ongoing phenomenon in others. While the prevalence of polyploid lineages indicates that this phenomenon is a common and successful evolutionary transition, whether polyploidization itself has a significant effect on patterns and rates of diversification remains an open question. Here we review evidence for the creative role of polyploidy in evolution. We present new estimates for the incidence of polyploidy in ferns and flowering plants based on a simple model describing transitions between odd and even base chromosome numbers. These new estimates indicate that ploidy changes may represent from 2 to 4% of speciation events in flowering plants and 7% in ferns. Speciation via polyploidy is likely to be one of the more predominant modes of sympatric speciation in plants, owing to its potentially broad-scale effects on gene regulation and developmental processes, effects that can produce immediate shifts in morphology, breeding system, and ecological tolerances. Theoretical models support the potential for increased adaptability in polyploid lineages. The evidence suggests that polyploidization can produce shifts in genetic systems and phenotypes that have the potential to result in increased evolutionary diversification, yet conclusive evidence that polyploidy has changed rates and patterns of diversification remains elusive.

Effects of polyploidy and reproductive mode on life history trait expression

“…2008; Neiman et al. 2009), and greater adaptive potential (Otto and Whitton 2000; Balao et al. 2011; Martin and Husband 2012; Selmecki et al.…”

“…2015) to costs associated with ploidy effects on organismal ecology ( e.g ., increased sensitivity to nutrient limitation, Neiman et al. 2013b,c) and genomic mutational load (Otto and Whitton 2000). While this growing body of research highlights the likelihood that ploidy changes are important with respect to organismal ecology and lineage evolution, the overall biological significance of polyploidy remains unclear (Otto and Whitton 2000; Mable et al.…”

“…2013b,c) and genomic mutational load (Otto and Whitton 2000). While this growing body of research highlights the likelihood that ploidy changes are important with respect to organismal ecology and lineage evolution, the overall biological significance of polyploidy remains unclear (Otto and Whitton 2000; Mable et al. 2011; Leslie 2014; Frawley and Orr‐Weaver 2015; Schoenfelder and Fox 2015).…”

“…2013). Like many other polyploid animals (reviewed in Otto and Whitton 2000; Neiman and Schwander 2011; Neiman et al. 2014), polyploid P. antipodarum are obligately asexual, producing nonrecombinant eggs via ameiotic parthenogenesis (Phillips and Lambert 1989).…”

“…2013) and as a potential contributor to the success of sexual P. antipodarum . We also used our data to evaluate a fundamental component of many hypotheses for sex as well as a potential evolutionary advantage of ploidy elevation: that sex, via recombination, and ploidy elevation, via the availability of extra allelic copies (Otto and Whitton 2000), will increase the phenotypic variance of heritable traits among sexually produced offspring relative to asexually produced offspring (Barton 1995) and in higher ploidy versus lower ploidy offspring.…”