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Testing Darwin's naturalization hypothesis in the Azores.
Hanno Schaefer1, Olivier J Hardy, Luís Silva
1Organismic and Evolutionary Biology, Harvard University, 22 Divinity Avenue, Cambridge, MA 02138, USA. hschaef@fas.harvard.edu
Ecology Letters
|February 16, 2011
Summary
Predicting invasive species is challenging. Invasive plants in the Azores are more likely to succeed when closely related native species are absent, a finding supported by phylogenetic nearest neighbour distance (PNND) and ecological traits.
Area of Science:
- Ecology
- Evolutionary Biology
- Conservation Biology
Background:
- Invasive species pose significant threats to global ecosystems, particularly on oceanic islands.
- Predicting the invasive potential of non-native species remains a complex challenge in ecological research.
- Few studies have identified reliable traits correlated with invasive success.
Purpose of the Study:
- To investigate the factors influencing the invasive potential of introduced plant species in the Azorean archipelago.
- To test Darwin's naturalization hypothesis using molecular phylogenetic and ecological trait data.
- To develop a predictive model for invasive success by combining phylogenetic and trait-based approaches.
Main Methods:
- Construction of a molecular phylogenetic dataset for the entire Azorean flora.
- Development of an ecological trait database for native and introduced plant species.
- Calculation of phylogenetic nearest neighbour distance (PNND) as a measure of evolutionary relatedness.
- Statistical analysis to correlate PNND and ecological traits with invasive status.
Main Results:
- Phylogenetic nearest neighbour distance (PNND) was significantly correlated with invasiveness.
- Introduced species were more likely to become invasive when closely related native species were absent, supporting Darwin's naturalization hypothesis.
- Specific ecological traits, including life form and seed size, also demonstrated predictive power for invasive success.
Conclusions:
- The absence of closely related native species is a key factor for successful plant invasion in the Azores.
- A combination of PNND and ecological traits offers a robust, universal predictor of invasiveness.
- This approach accounts for both the characteristics of introduced species and the receiving ecosystem, aiding conservation efforts.
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