Long-term effects of invasive species in novel communities: comparative analyses of population dynamics, and phenotypic and genetic changes

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Invasion biology has addressed or even solved several key questions about biological invasions, but the central issue of long-term effects of invasive species has remained critically unexplored. Several case studies exist about long-term population dynamics of invasive species and their impacts, but a general synthesis or understanding is currently lacking. This knowledge gap is critical, as long-term shifts in invader population densities and traits are likely and may have large consequences of ecological and economic interest. The current project aims to narrow the knowledge gap. More specifically, I propose to investigate: (1) time lags of invaders, (2) boom-bust and other population dynamics of invaders, (3) phenotypic and genetic changes of invaders, (4) population dynamics of native species affected by invaders, and (5) phenotypic and genetic changes of native species affected by invaders. For the investigations, a database will be set up with long-term datasets (each one covering at least 10 years of data) contributed by a large group of collaborators from Europe and North America. The database will include datasets from 90 invasive species: 30 species for each of the three best investigated major taxonomic groups (vertebrate animals, invertebrate animals, plants/algae) and for each of the three major types of habitat (freshwater, marine, terrestrial). For 18 invasive species, datasets for at least 10 locations each will be available. And for 60 invasive species (10 for each taxonomic group in both freshwater and terrestrial habitats), data will be available on their specific effects on native species. The database will allow for investigations at different levels, from major habitats and taxonomic groups to individual species, populations, and locations. Several research questions will be addressed, for instance: (1) Do differences in time lags among invaders correlate with characteristics of the invaders (e.g. life-history traits), invaded habitats (e.g. species richness), or invader-habitat interactions (e.g. climatic difference between the invader's native and exotic range)? (2) Which invaders with which characteristics show boom-bust dynamics, and in which habitats? These and other research questions related to the five central topics of the project (see above) will be addressed. Some studies on these questions will be led by my research group, while others will be led by collaborators. I propose three workshops over the three-year project period and several individual meetings in order to allow for knowledge exchange with collaborators. A website will be designed to serve as a platform for the team and the database. This website may also be helpful for future projects on the topic. The proposed project is at a research frontier and may spark future initiatives, e.g. on other long-term changes in novel communities.