Cultivation shapes genetic novelty in a globally important invader

Abstract

Acacia saligna is a species complex that has become invasive in a number of countries worldwide where it has caused substantial environmental and economic impacts. Understanding genetic and other factors contributing to its success may allow managers to limit future invasions of closely related species. We used three molecular markers to compare the introduced range (South Africa) to the native range (Western Australia). Nuclear markers showed that invasive populations are divergent from native populations and most closely related to a cultivated population in Western Australia. We also found incongruence between nuclear and chloroplast data that, together with the long history of cultivation of the species, suggest that introgressive hybridization (coupled with chloroplast capture) may have occurred within A. saligna. While we could not definitively prove introgression, the genetic distance between cultivated and native A. saligna populations was comparable to known interspecific divergences among other Acacia species. Therefore, cultivation, multiple large-scale introductions and possibly introgressive hybridization have rapidly given rise to the divergent genetic entity present in South Africa. This may explain the known global variation in invasiveness and inaccuracy of native bioclimatic models in predicting potential distributions.

Genetic diversity and differentiation of invasive <i>Acacia longifolia</i> in Portugal

“…However, A. senegal had a higher and significant genetic differentiation among populations (F ST = 0.100), probably due to the fact that it is native. A. saligna and A. pycnantha native (Australian) populations revealed higher genetic differentiation (F ST = 0.330) compared to the invasive (South African) range (F ST = 0.132) (Thompson et al, 2012). Still, invasive A. saligna demonstrates greater differentiation than A. longifolia.…”

“…Many molecular markers have been used in population and phylogenetic studies in acacias, including inter-simple sequence repeats (ISSRs), simple sequence repeats (SSRs or microsatellites), chloroplastidial DNA and internal and external transcribed spacers (ITS and ETS respectively) (Thompson et al, 2012(Thompson et al, , 2015Omondi et al, 2010Omondi et al, , 2016Harris et al, 2012;Miller et al, 2011;Le Roux et al, 2011Fredua-Agyeman et al, 2008;Mulumba et al, 2012;Josiah et al, 2008;Ndlovu et al, 2013;Murphy et al, 2010;Brown et al, , 2012. Furthermore, several SSRs markers have been developed for Acacia species, such as A. atkinsiana (Levy et al, 2014), A. brevispica (Otero-Arnaiz, 2005.…”

Biological Invasions, Climate Change, and Genomics

“…First, propagule pressure mitigates the impact of demographic stochasticity; second, increased genetic and phenotypic variation improves the chances of successful colonization (Colautti et al 2006;Simberloff 2009;Rius and Darling 2014). A recent meta-analysis, which controlled for the effects of population size, found strong evidence that higher levels of genotypic and phenotypic diversity in founder groups increased establishment success (Forsman 2014 Thompson et al 2012;Rius and Darling 2014).…”

Lantana camara L. (sensu lato): an enigmatic complex

“…Studies have revealed significant information regarding genetic variation, population differentiation, and introduction history of a few invasive species using molecular markers (Chun et al 2010, Thompson et al 2012, Vardien et al 2013. Few studies have also attempted to explore range expansion of L. camara in different countries (Vardien et al 2012, Ray andQuader 2014).…”