Predicting evolution in experimental range expansions of an aquatic model system

Area of Science:

• Ecology
• Evolutionary Biology
• Conservation Biology

Background:

• Predicting species range expansion is crucial for conservation and global change biology.
• Simultaneous ecological and evolutionary processes complicate these predictions.
• Understanding eco-evolutionary dynamics is key to forecasting species' responses to environmental change.

Purpose of the Study:

• To assess the predictability of evolutionary change during range expansions.
• To combine experimental evolution with mathematical modeling for range expansion dynamics.
• To investigate the role of dispersal evolution in driving species' range shifts.

Main Methods:

• Experimental evolution of *Paramecium caudatum* in microcosm populations simulating range core and front conditions.
• Mathematical modeling parameterized with empirical dispersal and growth data.
• Monitoring ecological dynamics and trait evolution, including genetic divergence (COI marker).

Main Results:

• Short-term evolution showed selection for increased dispersal at range fronts and higher growth rates overall.
• Mathematical model predictions quantitatively matched observed trait changes.
• Phenotypic and genetic divergence occurred between range core and front populations, with repeated fixation of specific COI genotypes.
• Long-term evolution at range fronts led to a dispersal syndrome and a competition-colonization trade-off.

Conclusions:

• Dispersal evolution is a significant driver of range expansions.
• Evolutionary trajectories at range fronts can be predictable, especially in simpler scenarios.
• Predicting range expansion dynamics may be feasible using key ecological and evolutionary parameters.