Understanding invasion history: genetic structure and diversity of two globally invasive plants and implications for their management

Abstract

Aim Resolving the origin of invasive plant species is important for understanding the introduction histories of successful invaders and aiding strategies aimed at their management. This study aimed to infer the number and origin(s) of introduction for the globally invasive species, Macfadyena unguis-cati and Jatropha gossypiifolia using molecular data. Location Native range: Neotropics; Invaded range: North America, Africa, Europe, Asia, Pacific Islands and Australia.Methods We used chloroplast microsatellites (cpSSRs) to elucidate the origin(s) of introduced populations and calculated the genetic diversity in native and introduced regions.Results Strong genetic structure was found within the native range of M. unguiscati, but no genetic structuring was evident in the native range of J. gossypiifolia. Overall, 27 haplotypes were found in the native range of M. unguis-cati. Only four haplotypes were found in the introduced range, with more than 96% of introduced specimens matching a haplotype from Paraguay. In contrast, 15 haplotypes were found in the introduced range of J. gossypiifolia, with all invasive populations, except New Caledonia, comprising multiple haplotypes.Main conclusions These data show that two invasive plant species from the same native range have had vastly different introduction histories in their non-native ranges. Invasive populations of M. unguis-cati probably came from a single or few independent introductions, whereas most invasive J. gossypiifolia populations arose from multiple introductions or alternatively from a representative sample of genetic diversity from a panmictic native range. As introduced M. unguis-cati populations are dominated by a single haplotype, locally adapted natural enemies should make the best control agents. However, invasive populations of J. gossypiifolia are genetically diverse and the selection of bio-control agents will be considerably more complex.

Comparison of growth traits between abundant and uncommon forms of a non-native vine, Dolichandra unguis-cati (Bignoniaceae) in Australia

“…Reconstructing the invasion history of this exotic species (or the two forms) is not possible because there are no records of their introduction, except that the species was first reported in a Melbourne Nursery catalogue in 1865 (Downey and Turnbull 2007). Introduction history of most ornamental plants is generally not or poorly recorded (Harris et al 2007;Prentis et al 2009). Studies on whether there has been any deliberate breeding selection of the species that resulted in the two forms are yet to be done.…”

Is Rapid Adaptive Evolution Important in Successful Invasions?

“…In fact, many of these characteristics are those generally associated with rare, endangered species. Empirical evidence supports one or more of these assumptions in a variety of invasive taxa (see, for example, Amsellem et al 2000Amsellem et al , 2001Schmid -Hempel et al 2007 ;Bailey et al 2009 ;Prentis et al 2009 ;Zang et al 2010 ; reviewed studies in Dlugosch & Parker 2008a ), supporting the notion that many species succeed in their new environment without need for adaptive evolution. However, there are a growing number of case studies that do not conform to this pattern (see, for example, Marrs et al 2008a ;Chun et al 2010 ; reviewed studies in Roman &Darling 2007 andParker 2008a ), or exhibit evidence for rapid adaptive evolution despite these constraints (see, for example, Dlugosch & Parker 2008b ).…”

DNA barcoding of invasive species

“…In red algae for example, absolute sequence divergence within species are typically below 1.8 -2.0% for the large subunit of the ribulose -1,5 -bisphosphate carboxylase oxygenase gene (RuBisCO) . As a tool for population genetics, when DNA barcode data are variable enough to highlight information below the species level, it may be possible to identify the source of introduction and population dynamics of the invasive species (see Kang et al 2007 ;Prentis et al 2009 ;Thomsen et al 2006 ). Phylogeographic and population genetic methods open up a wide range of opportunities for ecologists to infer and test recent and past evolutionary hypotheses such as estimates of effective population size (presence of population bottlenecks), size and/or frequency of original introduction(s), comparisons of genetic diversity between invasive and source populations, and synergistic interactions between hosts and pathogens (Wingfi eld et al, this volume).…”