Skip to main content

Individual Specialisation in Established Biological Invasions: importance and Ecological Impact

Periodic Reporting for period 1 - ISEBI (Individual Specialisation in Established Biological Invasions: importance and Ecological Impact)

Reporting period: 2017-12-01 to 2019-11-30

Differences among individuals are the substance on which natural selection acts. However, little is known about how individual traits influence invasion dynamics, to the extent that it has been argued that either bold, aggressive, highly competitive individuals, or individuals that are shy or cautious, and less competitive, may make successful invaders. Thus empirically identifying the constituent individual traits of successful invaders is key; but what is also missing is an understanding of the consequences of any such individual variation among invasive individuals for the native biota and communities. Yet this information is vital for informing management actions. This project utilises a natural experiment across invaded islands to determine the extent, covariance and persistence of individual variation across multiple traits (dietary, behavioural and cognitive) simultaneously in two invasive rat species in the wild. This approach explicitly tests how the fundamental ecological processes of competition and predation affect successful trait combinations, and will identify specific trait combinations, i.e. individual phenotypes, that cause particular individuals to have disproportionate impacts on native biota within an invasive species. The project examines hypotheses untested in either invasive species, or individuals of any species in natural contexts. The results will have important implications both for our theoretical understanding of biological invasions, and for conservation management actions addressing a global problem.
Work carried out during the reporting period involved successful field data collection from invasive rodents across five island locations that vary in their species compostiion. Behavioural and cognitive trials were conducted on all captured individuals, alongside the collection of associated metadata and physiological samples. Laboratory analyses on physiological samples have begun, but have not been completed across all locations. Individual variation has been identified in components of all examined traits, and ongoing analyses are examining the covariance in individuals within this multidimensional niche space. Further data collection has been planned in order to resolve these patterns more precisely through increasing sample sizes provided by the collection of further data at all field sites in the final year of the project. The research has already led to a number of additional avenues of inquiry (connections between behaviour and the microbiome, the economic impacts of invasions, see progress section below), the publication of papers on the presence and impacts of invasive species, as well as more broader public engagement with the early results of the research at governmental and research organisation, NGO and community group levels.
Progress so far has revealed substantial inter- and intra-specific variation in traits that can be exploited to achieve management objectives. The field research component of this project and its results are feeding into the design of experimental work that forms a component of a multi-million dollar grant to the crown research institute Landcare Research/Manaaki Whenua that is investigating the last survivors of eradication programs. Leveraging personality differences in these 'last survivors' to successfully remove them will ensure significant progress is made towards Predator Free 2050, New Zealand's 'moonshot' of eradicating numerous invasive mammalian predators. Success here will both inspire and enable advances in techniques around the world addressing this global problem.

Additional lines of invesigation and enquiry have also been established with state-of-the-art adn wider societal implications. Firstly, the experienced researcher has joined Invacost - part of the AlienScenario program. This international collaboration seeks to develop a more comprehensive understanding of the economic costs of biological invasions using a global, comprehensive database. A number of descriptive and synthetic papers are in preparation following an intensive workshop. The outcomes from this workshop are expecteed to have a influence on a broad range of fields outwith ecology as they comprehensively highlight for the first time the widescale impacts of biological invasions on human economic interests. Secondly, a successful pilot project has been established investigating links between the individual microbiome and key invasive traits. The results of this latter work are promising, and have been expanded to multiple fieldsites for the final year of the current project.