Niche expansions in introduced species: how common are they and can we predict them?

Mr Henry Hakkinen1

1University of Exeter, Penryn, United Kingdom

There have been a huge number of species introductions globally, but it is not clear how the novel biotic and abiotic factors species face in their introduced range determine their naturalised distributions. Species introductions represent a series of natural experiments that tests how strongly species are constrained by climatic limits, and how much they are limited by other non-climatic factors.

Increasingly, many introduced species have successfully established in climate dissimilar to their native habitat (‘niche expansion’). Using a newly compiled dataset of native and naturalised species ranges, we investigate the prevalence of niche expansions globally in terrestrial plants. We ask what factors increase the probability of a niche expansion, and whether the direction of niche expansion can be predicted in such events. By comparing species climatic niche overlap in multi-dimensional PCA space, we find that over 40% of introduced species have expanded their climate niche. Predominantly, expansions occur towards wetter or drier precipitation regimes, and to a much lesser extent expansion can also occur towards hotter or colder maxima and minima. Therefore precipitation often does not limit species’ range margins in the way we would expect based on species’ native ranges. We suggest that at ecologically productive native range margins species are often constrained by biotic interactions in their native range, and are often released from these biotic constraints following introductions. This means that climate effects on species’ native ranges may be strongly mediated by biotic interactions.


-BSc in Zoology at Durham University (2008-11)

-MbyRes at Durham University, looking at impacts of climate change on natural ecosystems and human society (2011-12)

-Worked as a professional IT admin, programmer and server admin in Prague (2012-2015)

-Currently studying for my PhD at the University of Exeter (based in Cornwall)

-Broad areas of interest include: species distribution models, especially focusing on the potential role of biotic interactions, range shifts caused by climate change, the process of naturalisation in introduced species, plant physiology and multi-taxonomic trends.

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