Wait, you’re thinking; this is an integrated pest management blog, not an FBI blog, right? Yes. For those of you who have never heard the term “geographic profiling,” it refers to a method used by crime fighters to track down serial killers, especially when they have a large pool of suspects. According to a group of scientists in Britain, who published a paper in the journal Ecography, scientists trying to stop the spread of invaders–invasive species, that is–can use the same tool to locate source populations of those invasive species, with considerably less effort than they may be using with many of the current source locator methods.
Invasive species are second to habitat destruction as the leading cause for biodiversity loss. They cost millions of dollars to control and can cause millions of dollars in damage through crop loss or landscape destruction. Scientists use information about the source of the species to understand its habitat, find predators and predict its patterns of invasion. Several tools aid in locating a species’ source, all of which use spatial analysis to pinpoint an area that may be the species’ native habitat.
Geographic profiling is a spatial analysis tool typically used by police in serial crimes. Police use geoprofiling to narrow down suspects when the list of suspects is too large to be useful in identifying the criminal. Geoprofiling makes two assumptions: first, the probability of a crime decreases as the distance from the criminal’s home base increases (distance decay function), and second, criminals are less likely to commit crimes too near their homes, for fear of being caught (buffer zone). Criminalists use these two assumptions to narrow the search area for the criminal.
Although invasive species probably don’t rationalize their distance from their home base as a means to escape capture, some of the assumptions on movement used to locate criminals can also be used on invasive species, according to scientists at Queen Mary University of London. The team of scientists compared geoprofiling to common methods of locating the sources of invasive species and found that geoprofiling was usually more reliable than the other methods.
The team compared the model to other widely used ways to gather spatial statistics, including center of minimum distance, spatial mean and spatial median. Geographic profiling outperformed all of them in addition to a kernel density approach. Just as in detective work, geographic profiling proved most useful when the number of sources of invasion were numerous.
GP models were used on all types of invasive species, including insects, animals and plants. The team was able to apply the principles of distance decay function and buffer. That’s because offspring or seedlings have better chances to thrive further from the parent, where they would have to compete for water and other nourishment, but often don’t travel too far on their own, since the environment can change the further it is from the source. GP models don’t take human intervention into account, however, which is the way many invasive pests move, through the movement of firewood.
Although the authors recommend more practical research on using the method for finding invasive species sources, they say that it could lead to more efficient searches for sources of invasive species.
Source: Stevenson, M.D., Rossmo, D.K., Knell, R.J., and Le Comber, S.C. Geographic profiling as a novel spatial tool for targeting the control of invasive species. Ecography 35: 001-012, 2012.
Filed under: Invasive species Tagged: | article in Ecography, buffer zone, distance decay function, geographic profiling, Geoprofiling, invasive species, Le Comber, Queen Mary University, spatial analysis
