Genetically based phenotypic differentiation between native and introduced tetraploids of Oxalis pes-caprae
Rapid evolutionary change often plays an important role in determining the success of plant invasions. Oxalis pes-caprae, a geophyte native to South Africa, has become a persistent invasive weed in several areas of the world, being particularly widespread in regions with a Mediterranean climate. The objective of this study was to look for the existence of genetically based phenotypic differences regarding competitive ability between O. pes-caprae native tetraploids and introduced tetraploids recently discovered in the invaded range of the western Mediterranean basin. For this, shoot emergence time, beginning of flowering, chlorophyll fluorescence parameters, aboveground biomass, final offspring bulb production and survival were measured in a greenhouse experiment with plants from both ranges growing alone or in competition with Trifolium repens. Results demonstrated significant differences between introduced and native tetraploids, with plants from the invaded range emerging earlier, beginning flowering later and producing more aboveground biomass and offspring bulbs than South African plants. Furthermore, introduced plants showed an increase in aboveground biomass when grown with T. repens, and affected T. repens growth more severely than their native conspecifics, which may be indicative of a greater competitive ability. These findings provide strong evidence for genetic differentiation between introduced and native tetraploids. It is suggested that founder events and rapid post-introduction adaptive evolution may have contributed, independently or in concert, to this divergence.
KeywordsBiological invasions Oxalis pes-caprae Interspecific competition Genetic differentiation
Authors are thankful to Western Cape Nature Conservation Board and Department of Environment and Nature Conservation, Northern Cape, for providing authorizations to collect and undertake scientific research (No. AAA005-00218-0028). The authors are also thankful to Victoria Ferrero and Joana Costa for their help in bulb collection. Authors would also like to thank the two anonymous Reviewers and the Associate Editor Dr. Carla Lambertini for all the constructive comments made to previous versions of the manuscript. This research was supported by FEDER funds through the COMPETE Program, Project ReNATURE (Centro 2020, Centro-01-0145-FEDER-000007), and by Portuguese Foundation for Science and Technology (FCT) funds within the Project PTDC/BIA-BIC/110824/2009. FCT also supported the work of Sílvia Castro (FCT/BPD/41200/2007, Starting Grant IF/01267/2013), Mariana Castro (SFRH/BD/89617/2012) and Ana Martins (SFRH/BD/86959/2012).
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Conflict of interest
The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
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