title: Multiple dispersal vectors drive range expansion in an invasive marine species.
abstract: The establishment and subsequent spread of invasive species is widely recognized as one of the most threatening processes contributing to global biodiversity loss. This is especially true for marine and estuarine ecosystems, which have experienced significant increases in the number of invasive species with the increase in global maritime trade. Understanding the rate and mechanisms of range expansion is therefore of significant interest to ecologists and conservation managers alike. Using a combination of population genetic surveys, environmental DNA (eDNA) plankton sampling and hydrodynamic modelling, we examined the patterns of introduction of the predatory Northern Pacific seastar (Asterias amurensis) and pathways of secondary spread within southeast Australia. Genetic surveys across the invasive range reveal some genetic divergence between the two main invasive regions and no evidence of ongoing gene flow, a pattern that is consistent with the establishment of the second invasive region via a human-mediated translocation event. In contrast, hydrodynamic modelling combined with eDNA plankton sampling demonstrated that the establishment of range expansion populations within a region is consistent with natural larval dispersal and recruitment. Our results suggest that both anthropogenic and natural dispersal vectors have played an important role in the range expansion of this species in Australia. The multiple modes of spread combined with high levels of fecundity and a long larval duration in A. amurensis suggests it is likely to continue its range expansion and significantly impact Australian marine ecosystems.
authors.affiliation: Bioinformatics Core Research Group, Deakin University, 75 Pigdons Road, Locked Bag 20000, Geelong, Vic., 3220, Australia. m.richardson@deakin.edu.au.|School of Life and Environmental Sciences, Centre for Integrative Ecology, Deakin University, Waurn Ponds Campus, 75 Pigdons Road, Locked Bag 20000, Geelong, Vic., 3220, Australia. m.richardson@deakin.edu.au.
authors.forename: Mark F
authors.identifier: 0000-0002-1650-0064
authors.initials: MF
authors.lastname: Richardson
authors.affiliation: School of Life and Environmental Sciences, Centre for Integrative Ecology, Deakin University, Waurn Ponds Campus, 75 Pigdons Road, Locked Bag 20000, Geelong, Vic., 3220, Australia.
authors.forename: Craig D H
authors.initials: CD
authors.lastname: Sherman
authors.affiliation: Applied Sciences Group, Environmental Protection Authority, Vic., 3085, Australia.
authors.forename: Randall S
authors.initials: RS
authors.lastname: Lee
authors.affiliation: School of Science and Centre for Environmental Sustainability and Remediation, RMIT University, PO Box 71, Bundoora, Vic., 3083, Australia.
authors.forename: Nathan J
authors.initials: NJ
authors.lastname: Bott
authors.affiliation: School of Life and Environmental Sciences, Centre for Integrative Ecology, Deakin University, Waurn Ponds Campus, 75 Pigdons Road, Locked Bag 20000, Geelong, Vic., 3220, Australia.
authors.forename: Alastair J
authors.initials: AJ
authors.lastname: Hirst
mesh_terms: D063147:Animal Distribution; D000818:Animals; D047271:Asterias / Q000235:genetics*; D001315:Australia; D017753:Ecosystem; D014644:Genetic Variation; D005828:Genetics, Population; D060005:Genotyping Techniques; D057446:Hydrodynamics; D058865:Introduced Species; D007814:Larva; D018895:Microsatellite Repeats; D010933:Plankton
keywords: environmental DNA; hydrodynamic and dispersion modelling; invasive species; larval dispersal; population genetics; range expansion