title: Is invasion success of Australian trees mediated by their native biogeography, phylogenetic history, or both?
abstract: For a plant species to become invasive it has to progress along the introduction-naturalization-invasion (INI) continuum which reflects the joint direction of niche breadth. Identification of traits that correlate with and drive species invasiveness along the continuum is a major focus of invasion biology. If invasiveness is underlain by heritable traits, and if such traits are phylogenetically conserved, then we would expect non-native species with different introduction status (i.e. position along the INI continuum) to show phylogenetic signal. This study uses two clades that contain a large number of invasive tree species from the genera Acacia and Eucalyptus to test whether geographic distribution and a novel phylogenetic conservation method can predict which species have been introduced, became naturalized, and invasive. Our results suggest that no underlying phylogenetic signal underlie the introduction status for both groups of trees, except for introduced acacias. The more invasive acacia clade contains invasive species that have smoother geographic distributions and are more marginal in the phylogenetic network. The less invasive eucalyptus group contains invasive species that are more clustered geographically, more centrally located in the phylogenetic network and have phylogenetic distances between invasive and non-invasive species that are trending toward the mean pairwise distance. This suggests that highly invasive groups may be identified because they have invasive species with smoother and faster expanding native distributions and are located more to the edges of phylogenetic networks than less invasive groups.
authors.affiliation: National Research Collections Australia, CSIRO National Facilities and Collections, GPO Box 1600, Canberra, ACT 2601, Australia. joe@acaciamulga.net.|Office of International Science and Engineering, National Science Foundation, Arlington, Virginia 22230, USA.
authors.forename: Joseph T
authors.initials: JT
authors.lastname: Miller
authors.affiliation: Department of Mathematical Sciences, Centre for Invasion Biology, Stellenbosch University, Matieland 7620, South Africa.|BioMath Group, African Institute for Mathematical A10 Sciences, Cape Town 7652, South Africa.
authors.forename: Cang
authors.initials: C
authors.lastname: Hui
authors.affiliation: University and Jepson Herbaria, and Department of Integrative Biology, University of California, Berkeley, CA 94720-2465, USA.
authors.forename: Andrew
authors.initials: A
authors.lastname: Thornhill
authors.affiliation: Centre for Invasion Biology, Department of Botany & Zoology, Stellenbosch University, Matieland 7620, South Africa.
authors.forename: Laure
authors.initials: L
authors.lastname: Gallien
authors.affiliation: Centre for Invasion Biology, Department of Botany & Zoology, Stellenbosch University, Matieland 7620, South Africa.
authors.forename: Johannes J
authors.initials: JJ
authors.lastname: Le Roux
authors.affiliation: Centre for Invasion Biology, Department of Botany & Zoology, Stellenbosch University, Matieland 7620, South Africa.
authors.forename: David M
authors.initials: DM
authors.lastname: Richardson
keywords: Acacia; eucalypts invasiveness; introduced; naturalized; phylogenetic signal; spatial clustering; tree invasions.