Genetic diversity in three invasive clonal aquatic species in New Zealand

Abstract

BackgroundElodea canadensis, Egeria densa and Lagarosiphon major are dioecious clonal species which are invasive in New Zealand and other regions. Unlike many other invasive species, the genetic variation in New Zealand is very limited. Clonal reproduction is often considered an evolutionary dead end, even though a certain amount of genetic divergence may arise due to somatic mutations. The successful growth and establishment of invasive clonal species may be explained not by adaptability but by pre-existing ecological traits that prove advantageous in the new environment. We studied the genetic diversity and population structure in the North Island of New Zealand using AFLPs and related the findings to the number of introductions and the evolution that has occurred in the introduced area.ResultsLow levels of genetic diversity were found in all three species and appeared to be due to highly homogeneous founding gene pools. Elodea canadensis was introduced in 1868, and its populations showed more genetic structure than those of the more recently introduced of E. densa (1946) and L. major (1950). Elodea canadensis and L. major, however, had similar phylogeographic patterns, in spite of the difference in time since introduction.ConclusionsThe presence of a certain level of geographically correlated genetic structure in the absence of sexual reproduction, and in spite of random human dispersal of vegetative propagules, can be reasonably attributed to post-dispersal somatic mutations. Direct evidence of such evolutionary events is, however, still insufficient.

Genetic and epigenetic changes during the invasion of a cosmopolitan species (Phragmites australis)

“…Unlike many invasive clonal species spreading mostly by vegetative reproduction (Gao, Geng, Li, Chen, & Yang, 2010; Lambertini et al., 2010; Richards et al., 2012), the invasion of P. australis in North America contributes to a reproduction strategy combining sexual and vegetative propagation (Albert, Brisson, Belzile, Turgeon, & Lavoie, 2015; McCormick, Kettenring, Baron, & Whigham, 2010). The high genetic diversity in P. australis makes it more difficult to detect the epigenetic changes during the invasion.…”

“…Some species could obtain more genetic diversity through multiple introductions and hybridization during the invasion process (Genton, Shykoff, & Giraud, 2005; Kelager, Pedersen, & Bruun, 2013; Rosenthal, Ramakrishnan, & Cruzan, 2008; Suehs, Affre, & Médail, 2004), but other invasive species, especially clonal plants, may maintain low levels of genetic diversity after gene drift accompanied by invasion (Hollingsworth & Bailey, 2000; Lambertini et al., 2010; Lindholm et al., 2005; Loomis & Fishman, 2009). While adaptation is accomplished by genetic changes through mutation, drift and selection are very slow for some introduced species, so epigenetic mechanisms can provide an alternative source of ecologically phenotypic diversity for rapid adjustment (Medrano, Herrera, & Bazaga, 2014).…”

A study of the genetic variation of the aquatic fern Marsilea quadrifolia L. preserved in botanical collections in Poland and originated from natural populations in Europe

“…To distinguish the source of genetic variation, whether it is produced by somatic mutations or due to outcrossing in clonal outcrossing plant species, an analysis of the spectrum of pairwise genetic differences was proposed by several authors (ArnaudHaond et al, 2007;Lambertini et al, 2010;Mock et al, 2008;Rozenfeld et al, 2007). When both mechanisms are involved in the creation of variation, this spectrum shows a bimodal distribution.…”

The fitness of the environments of air and water for photosynthesis, growth, reproduction and dispersal of photoautotrophs: An evolutionary and biogeochemical perspective

“…Many aquatic macrophytes are rhizomatous (Sosnova et al, 2010) and this along with asexual reproduction tends to result in clonal populations (Grace, 1993) and in general lower population genetic diversity in many populations (Barrett et al, 1993) although not in all (Harris et al, 1992). The most obvious example of low genetic diversity in freshwater macrophytes occurs with invasive species, especially in dioecious species such as Elodea (Lambertini et al, 2010).…”