DNA ploidy‐level variation in native and invasive populations of Lythrum salicaria at a large geographical scale

Abstract

Aim This study aimed to document precisely the patterns of DNA ploidy variation in the native and secondary ranges of Lythrum salicaria distribution. The hypothesis that species invasiveness had been induced by a switch in ploidy level was addressed. Location Europe, Middle East, North America. Methods DNA ploidy levels of 1884 progenies of 578+ plants collected at 124 localities were determined by DAPI flow cytometry. Results Large cytotype variation (2x, 3x, 4x and 6x) was found across the native area of distribution (64 populations covering 12 European and two Middle Eastern countries). DNA hexaploids were detected for the first time, and rare DNA triploids were reliably confirmed. DNA tetraploids largely prevailed across the native range studied, while DNA diploids and DNA hexaploids were recorded only in Israel and Turkey, respectively. DNA triploid progenies occurred in one population from Hungary (together with DNA tetraploids). Sympatric growth of DNA tetraploids and DNA hexaploids was repeatedly encountered in Turkey. In contrast, cytotype uniformity was a typical feature of the invasive North American plants. Sixty populations, covering 13 states of the USA and provinces of Canada, were characterized by the presence of only DNA tetraploids. Main conclusions Several L. salicaria cytotypes (2x, 3x, 4x, 6x) occur in the native range of distribution, with much variation concentrated in the Middle Eastern countries, whereas only DNA tetraploids appeared to occur in North America. Our data show that the invasive spread of North American populations was not triggered by differences in ploidy level. Alternative explanations should be sought.

Can enemy release explain the invasion success of the diploid Leucanthemum vulgare in North America?

“…This is in accordance with surveys that had been conducted by Fernald (1903) and Mulligan (1958) in eastern North America where only a few populations of L. ircutianum were found. The higher invasion success of the diploid L. vulgare is in contrast to studies that found a positive association between polyploidy and invasiveness in plants (Lafuma et al 2003;Kubátová et al 2008;Schlaepfer et al 2008;Treier et al 2009;Pandit et al 2011Pandit et al , 2014te Beest et al 2012). The higher abundance of L. vulgare in the introduced range could potentially be explained by differences in introduction pressure between the two species.…”

“…Polyploidy has been found to be overrepresented in invasive plants (Pandit et al 2011(Pandit et al , 2014 and in various taxa with more than one ploidy level in the native range, only polyploids have become invasive (e.g. Lafuma et al 2003;Kubátová et al 2008;Schlaepfer et al 2008;Treier et al 2009). Furthermore, polyploids are expected to exhibit increased concentrations of secondary metabolites compared to their diploid progenitors and may therefore experience greater levels of herbivore resistance (Levin 1983;Dhawan and Lavania 1996).…”

The “Polyploid Hop”: Shifting Challenges and Opportunities Over the Evolutionary Lifespan of Genome Duplications

“…This is an open question, but the many cases where both cytotypes occur in their native range but only polyploids do in the invasive ranges (Lafuma et al, 2003;Mandák et al, 2005;Kubátová et al, 2007;Schlaepfer et al, 2008;Treier et al, 2009) suggest a potential pre-adaptation of polyploids for invasiveness (te Beest et al, 2012). However, environmental stresses also increase the rate of unreduced gamete formation and thus of polyploidization events (Bretagnolle and Thompson, 1995;Ramsey and Schemske, 1998).…”

The polyploid nature of Cenchrus ciliaris L. (Poaceae) has been overlooked: new insights for the conservation and invasion biology of this species – a review

“…We suggest, therefore, that knowledge of polyploidy of the germplasm of C. ciliaris introduced in these areas is essential in comparative studies of invasive and native populations. Critical analysis of the relationship between invasiveness and polyploidy will require study of the polyploid complex, in which one may directly compare polyploids and their diploid relatives under field conditions (Kubátová et al 2008;Treier et al 2009;Schlaepfer et al 2010).…”