Human usage in the native range may determine future genetic structure of an invasion : insights from Acacia pycnantha
Date
2013-10
Authors
Le Roux, Johannes J.
Richardson, David M.
Wilson, John R. U.
Ndlovu, Joice
Journal Title
Journal ISSN
Volume Title
Publisher
BioMed Central
Abstract
Background: The influence of introduction history and post-introduction dynamics on genetic diversity and
structure has been a major research focus in invasion biology. However, genetic diversity and structure in the
invasive range can also be affected by human-mediated processes in the native range prior to species
introductions, an aspect often neglected in invasion biology. Here we aim to trace the native provenance of the
invasive tree Acacia pycnantha by comparing the genetic diversity and structure between populations in the native Australian range and the invasive range in South Africa. This approach also allowed us to explore how human actions altered genetic structure before and after the introduction of A. pycnantha into South Africa. We
hypothesized that extensive movement and replanting in A. pycnantha’s Australian range prior to its
introduction to South Africa might result in highly admixed genotypes in the introduced range, comparable
genetic diversity in both ranges, and therefore preclude an accurate determination of native provenance(s)
of invasive populations.
Results: In the native range Bayesian assignment tests identified three genetic clusters with substantial
admixture and could not clearly differentiate previously identified genetic entities, corroborating admixture as
a result of replantings within Australia. Assignment tests that included invasive populations from South Africa
indicated similar levels of admixture compared to Australian populations and a lack of genetic structure.
Invasive populations of A. pycnantha in South Africa are as genetically diverse as native populations, and
could not be assigned to particular native range regions.
Conclusions: Our results indicate that the genetic structure of A. pycnantha in Australia has been greatly
altered through various planting initiatives. Specifically, there is little geographic structure and high levels
of admixture. While numerous introduction history scenarios may explain the levels of admixture observed
in South Africa, planting records of A. pycnantha in Australia suggest that populations were probably already
admixed before propagules were introduced to South Africa. These findings have important implications for
the management of invasive A. pycnantha populations in South Africa, especially for classical biological
control, and more broadly, for studies that aim to understand the evolutionary dynamics of the invasion
process.
Description
Publication of this article was funded by the Stellenbosch University Open Access Fund.
The original publication is available at http://www.biomedcentral.com/bmcecol/
The original publication is available at http://www.biomedcentral.com/bmcecol/
Keywords
Acacia pycnantha, Biological invasions, Genetic structure, Native range
Citation
Le Roux, J. J., Richardson, D. M., Wilson, J. R. U. & Ndlovu, J. 2013. Human usage in the native range may determine future genetic structure of an invasion: insights from Acacia pycnantha. BMC Ecology, 13:37, doi:10.1186/1472-6785-13-37.