Cultivar selection prior to introduction may increase invasiveness: evidence from Ardisia crenata

Abstract

Ardisia crenata (Myrsinaceae), an evergreen shrub with attractive red fruits introduced from Japan to the USA for ornamental purpose, invades the understory of mesic hardwood forests, forming dense patches (up to 300 stems per m 2 ), and competitively displaces native understory plants by creating dense local shade. Comparison of the wild genotype that grows in mature evergreen broadleaf forests in central Kyushu, Japan, with the ecotype invading north central Florida revealed how selection for desirable cultivars might have inadvertently selected for traits that enhance the invasive potential of the species. In Japanese wild populations in deeply shaded evergreen forests, natural selection apparently maintained efficient architecture with a low degree of self-shading and large seed mass to enhance seedling shade tolerance. Cultivar selection for showy appearance can explain the greater fecundity but smaller seed size observed in the Florida populations compared to the Japanese population. Artificial selection for densely foliated appearance can also explain the greater degree of self-shading and less-efficient light use in the Florida genotype compared to the Japanese wild type grown under a common environment. Furthermore, the Florida ecotype allocated more biomass to root carbohydrate storage. These trait modifications resulted in slower growth rates, but greater competitive ability to cast shade upon neighbors and higher resprouting potential in the Florida populations. How traits are modified through the processes of artificial selection and cultivation must be taken into consideration in the evolutionary ecology of many other invasive plants introduced as ornamental plants.

The effects of an exotic palm on a native palm during the first demographic stages: contributions to ecological management

“…nation for the differences in performance between the two palm species is that the native palm has not been domesticated and therefore has no history of artificial selection . In contrast, of A. cunninghamiana has been used as an ornamental, and it has probably undergone artificial selection for specific desirable traits such as vigorous individuals that could reproduce more efficiently (Kitajima et al 2006).…”

The role of intraspecific hybridization in the evolution of invasiveness: a case study of the ornamental pear tree Pyrus calleryana

“…In some cases, invasive genotypes may originate unintentionally after crossing occurs between different cultivars planted in the landscape, as in P. calleryana (described above) and Lythrum salicaria (Anderson and Ascher 1993). Cultivar selection prior to introduction itself can also increase invasiveness, as with selection for showy appearance and dense foliage of Japanese Ardisia crenata in the United States (Kitajima et al 2006). Consequently, some plant breeders have begun examining individual cultivars for invasive traits (Anderson et al 2006), such as abundant seed set and high seed germination (e.g.…”

Drivers of Vegetation Species Diversity and Composition in Urban Ecosystems

“…Traits that might predict invasiveness include polyploidy (having multiple copies of chromosomes; te Beest et al 2011), low seed mass and short juvenile periods ( Rejmanek and Richardson 1996), and self-compatibility (not needing pollen from another individual to reproduce sexually; Hao et al 2010). In addition, human selection for desirable ornamental characteristics, such as attractive berries, may inadvertently increase urban species' potential invasiveness (Kitajima et al 2006).…”