PREDICTING BIOLOGICAL INVASIONS WITH CLIMATE CHANGE
Minnesota Terrestrial Plants and Pests Center/LCCMR (2019-2022)
Minnesota Terrestrial Plants and Pests Center/LCCMR (2016-2018)
A fundamental problem in ecology and evolutionary biology is to explain the geographical distribution of species. For some species, range limits are remarkably stable through time and the primary factor limiting range expansion is adaptive evolution to novel environments. For other species, range limits are shifting either because of changing environments (e.g. climate change) or because species are in the process of colonizing new continents or regions (e.g. invasive species). Given unprecedented human influences on global environments, we are increasingly in need of predictive models that describe distribution shifts in order to conserve and manage natural ecosystems.
Invasive species are an important exception in terms of the study of geographic range limits. While most species have stable range limits, or margins that have exhibited gradual shifts in response to recent climate change, invasive species tend to exhibit explosive population growth and rates of expansion. This presents a particularly complex problem for researchers: the location of range limits may be affected by the suitability of environments (e.g. climate) or might be simply determined by the opportunity to disperse to areas that are already suitable but have not yet been colonized. Therefore, predictive models of invasive species spread must consider both equilibrium and non-equilibrium processes.
Plant communities have changed dramatically due to the introduction of non-native species. It has been estimated that the United States now contains ca. 5000 non-native plant species (Morse et al. 1995) and 17,000 native plant species (Morin 1995). Although most non-native species do not become invasive, the subset that do can have major effects on natural communities and be costly to eradicate or manage.
Predicting species invasions can be critical to their control. Without the ability to anticipate the direction and rate of spread, land managers must often respond after the problem is difficult to contain or manage (Rejmánek et al. 2005). Species distribution models (SDMs) have been increasingly employed in this arena. These models have been generated across quite different spatial scales (regional, continental, global) to predict spatial spread and inform management actions. At a minimum, they provide a first step toward understanding the environmental drivers of population dynamics and geographic distributions. They also provide testable hypotheses that can be evaluated with field experiments and long-term observation.
Our project focuses on eight plant species that are invasive in natural or agricultural ecosystems of the Upper Midwest. These eight species have only recently been observed in the northern tier of the Midwest, including Minnesota and neighboring regions.
One potential explanation is that changing climates have facilitated northward range expansion; however, the potential distributions of these species remain unknown. We are using SDMs to predict invasive species’ distributions under current and future climates to examine the controls on range expansion (e.g. limited dispersal or limited adaptation) and to guide management efforts in Minnesota.
This project is funded by the Minnesota Invasive Plants and Pests Center (MITPPC) and The Legislative-Citizen Commission on Minnesota Resources (LCCMR).
Briscoe Runquist, R.D., T. Lake, P. Tiffin, and D.A. Moeller. 2019. Species distribution models throughout the invasion history of Palmer amaranth predict regions at risk of future invasion and reveal challenges with modeling rapidly shifting geographic ranges. Scientific Reports, in press.