Multiple origins of polyploidy and the geographic structure ofHeuchera grossulariifolia

Abstract

Multiple origins of polyploidy from an ancestral diploid plant species were investigated using restriction site polymorphism and sequence variation in the chloroplast DNA (cpDNA) of Heuchera grossulariifolia (Saxifragaceae). Phylogenetic analysis indicated that autopolyploidy has arisen at least twice in the evolutionary history of this species and potentially up to as many as seven times. These results suggest a greater range of independent polyploid origins as compared to a previous study of H. grossulariifolia using cpDNA restriction sites that indicated a minimum of three independent origins. Moreover, most polyploid populations did not contain cpDNA haplotypes from a single origin, but rather combined haplotypes from at least two polyploid origins. Past migration among polyploid populations of independent origin or localized polyploid formation may explain the distribution of polyploid haplotypes within and among populations. The analysis also revealed a discrepancy between relatedness and geographical location. In nearly all sympatric populations of diploids and polyploids, polyploids had the same cpDNA haplotypes as diploids from a geographically remote population. This geographical discordance has several possible explanations, including small sample sizes, extinction of parental diploid haplotypes, chloroplast introgression, and homoplasy in the cpDNA sequence data. We conclude that the recurrent formation of polyploids is an important evolutionary mechanism in the diversification of H. grossulariifolia.

Systematics and phylogeography of the Dactylorhiza maculata complex (Orchidaceae) in Scandinavia: insights from cytological, morphological and molecular data

“…Van Dijk and BakxSchotman (1997) on Plantago media; Segraves et al (1999) on Heuchera grossulariifolia] have shown that autopolyploid taxa can arise recurrently. In general, recurrent autopolyploidization is thought to be a common phenomenon (Ramsey and Schemske 1998).…”

Origins, colonization, and lineage recombination in a widespread perennial soybean polyploid complex

“…Most of these studies, however, involve only a single marker, often chloroplast DNA (cpDNA), and thus leave open the question of whether gene exchange and subsequent lineage recombination occurs among polyploids having different origins. Relatively few studies of wild plants (5,6) have documented both multiple origins of a polyploid species and gene flow among its genetically distinct populations. Thus, it is not known whether most wild allopolyploid species exist in nature as single gene pools or, instead, as a set of isolated populations unlinked by gene exchange.…”

Partial interfertility between independently originated populations of the neo-allopolyploid Mimulus peregrinus

“…Although there is ample genetic evidence of multiple origins across a variety of allopolyploid taxa (e.g. Wyatt et al 1988;Ashton and Abbott 1992;Franzke and Mummenhoff 1999;Segraves et al 1999;Soltis et al 2004;Beck et al 2012;Mavrodiev et al 2015;Servick et al 2015;Vallejo-Marín et al 2015), fewer studies have experimentally compared the interfertility of independently originated populations. For instance, Modliszewski and Willis (2012) investigated the interfertility of populations of independent origin of the allotetraploid Mimulus sookensis (2n = 4x = 56), which is the polyploid derivative of hybrids between M. guttatus and M. nasutus (2n = 28) (Benedict et al 2012).…”

“…Wyatt et al 1988;Soltis and Soltis 1991;Ashton and Abbott 1992;Doyle et al 1999;Segraves et al 1999;Beck et al 2012;Modliszewski and Willis 2012;Sampson and Byrne 2012;Mavrodiev et al 2015;Servick et al 2015;Vallejo-Marín et al 2015). Although each instance of polyploid formation may result in limited genetic diversity, mating between independently generated polyploids may introduce genetic variation into the nascent lineage and create new genetic combinations .…”