Invasive species can have a negative effect on our native species, competing with them for food, eating them, and bringing diseases. Some well known examples in the UK are the grey squirrel, rhododendrons, the harlequin ladybird and Japanese knotweed. Global transport and a changing climate mean the risk of invasive species is increasing, with potential devastating effects. The forestry industry, for example, is particularly vulnerable to the threat of insect pests eating trees.
Knowing this, scientists are keen to predict which areas are under threat of invasion by specific species. These predictions are based on the assumption that a species will colonise areas with the same conditions as its native range. A 2012 paper in Science investigated whether this is true for 50 species of invasive plant – do they occupy the same ‘niche’ in their new range as their native range?
North America and Europe inhabit similar latitudes and hence have similar climatic conditions, so it isn’t surprising that they are vulnerable to the invasion of species from each other. This paper focuses on species invasions on these two continents. Although the invasive species we are familiar with have colonised the UK, Europe is actually a ‘net exporter of invasive species’. Historically there are many examples of Europeans settling on other continents. The spread of people out of Europe has often caused the spread of invasive species.
The paper reports there was little evidence that species invading new areas changed the niche they inhabited. The authors suggested that where, occasionally, plants do invade a new niche the reasons can include hybridisation with a native species or relative freedom from predators that were limiting their distribution in their native ranges.
Having found that species stay in the same conditions in their new range, the authors conclude that it is reasonable to base computer models on the current conditions on which a species are found. This is true both for models predicting the spread of invasive species introduced into new geographical areas and those predicting how species will respond to climate change.
Petitpierre, B., Kueffer, C., Broennimann, O., Randin, C., Daehler, C., & Guisan, A. (2012). Climatic Niche Shifts Are Rare Among Terrestrial Plant Invaders Science, 335 (6074), 1344-1348 DOI: 10.1126/science.1215933