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Evolution of density-dependent movement during experimental range expansions.

E A Fronhofer^1,2, S Gut¹, F Altermatt^1,2

¹Department of Aquatic Ecology, Eawag: Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, Switzerland.

Journal of Evolutionary Biology

|October 5, 2017

Summary

Evolutionary changes during range expansions drive changes in movement behavior. Experiments show range expansions led to negatively density-dependent movement at margins and increased competitive ability in cores.

Keywords:

Tetrahymena thermophila biological invasion context-dependent dispersal dispersal evolution experimental evolution movement protist microcosm

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Area of Science:

Ecology
Evolutionary Biology
Genetics

Background:

Range expansions and biological invasions are dynamic processes influenced by evolutionary changes.
Dispersal and movement behaviors are key drivers of spatial processes like range expansions.
The evolution of density-dependent movement during range expansions remains under-explored experimentally.

Purpose of the Study:

To experimentally test theories predicting the evolution of increased movement at low densities during range expansions.
To investigate evolutionary changes in movement and competitive ability in a model system.
To understand the role of evolving reaction norms in range dynamics.

Main Methods:

Utilized highly replicated and controlled range expansion experiments.
Employed the protist model system Tetrahymena thermophila across multiple genotypes.
Observed evolutionary changes in movement and competitive ability in range margins and cores.

Main Results:

Evolutionary changes in movement were observed, even without initial standing genetic variation.
Range expansions resulted in the evolution of negatively density-dependent movement at range margins.
Increased intrastrain competitive ability and decreased population growth rates were observed in range cores.

Conclusions:

Movement and dispersal should be viewed as evolving reaction norms and plastic life-history traits.
Findings are relevant for understanding range expansions, biological invasions, and spatially structured systems.
Highlights the importance of evolutionary dynamics in ecological processes.