Developing and testing an eco-evolutionary theory for range limits

The project will test how ecological and evolutionary processes determine species' range boundaries. A species' geographic distribution refers to the places where populations of that species can be found. The edge of a species' distribution is its geographic range boundary - the species can be found within this boundary, but not outside of it.

Although all species have boundaries, the underlying mechanisms determining where and how they form remain poorly understood for two key reasons. First, some of the hypothesized mechanisms are difficult to manipulate in natural settings. Second, researchers have historically approached this problem from either an ecological or evolutionary perspective which can be difficult to merge.

Here, the researchers will use a combination of computation models and laboratory experiments on flour beetles growing in artificial landscapes to test multiple hypotheses behind the factors that determine species' geographic distributions. A better understanding of the factors that determine range limits will be crucial for improved management of invasive and endangered species and for predicting how species will change their ranges in response to climate change.

In addition to potential insights into pressing conservation concerns, the researchers will actively engage the public through interactive activities at local farmers’ markets to teach the public, particularly children, about the importance of ecology and evolution in natural populations and agriculture.

The researchers will use microcosms of the red flour beetle, Tribolium castaneum, a common agricultural pest species, to manipulate the rate of change in environmental conditions, the level of dispersal, and the presence of an ecological competitor. These factors will be systematically varied to test each of their direct and interacting effects on the formation and location of range limits.

Further, the researchers will use single patch controls to test for adaptation to different environmental conditions in the absence of dispersal from populations in other environmental conditions. DNA of beetles from the microcosm landscapes and the single patch controls will be sequenced to identify the genomic basis of adaptation and quantify the amount of genetic drift at the range edges.

These experimental results will be combined with genetically explicit simulation models to test additional parameter values not tested in the mesocosm experiments. Overall, the project will provide critical data testing how environmental gradients and interspecific interactions interact with dispersal, adaptation, and genetic drift to affect range limits.

This information may also be useful in controlling this agricultural pest species. The project will provide training opportunities for graduate and undergraduate students.

This project is jointly funded by Population and Community Ecology, the Established Program to Stimulate Competitive Research (EPSCoR), and Evolutionary Processes.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.