How does spatial dispersal network affect the evolution of parasite local adaptation?

Area of Science:

• Evolutionary Biology
• Ecology
• Microbial Genetics

Background:

• Host-parasite coevolutionary dynamics are influenced by parasite local adaptation.
• Dispersal and population structure are key factors affecting parasite local adaptation.
• Understanding these factors is crucial for predicting coevolutionary trajectories.

Purpose of the Study:

• To investigate the impact of spatial dispersal network topology on bacteriophage parasite local adaptation to bacterial hosts.
• To determine how landscape structure influences the evolution of parasite infectivity and local adaptation.
• To compare different definitions of local adaptation under varying dispersal scenarios.

Main Methods:

• Experimental evolution using bacteriophage-bacteria systems in controlled landscapes.
• Manipulation of spatial dispersal network shapes within experimental environments.
• Quantification of phage infectivity breadth and assessment of local adaptation using multiple definitions (local vs. foreign, home vs. away, local vs. global).

Main Results:

• Dispersal consistently led to the evolution of phages with broader infectivity ranges, irrespective of landscape topology.
• Spatial variation in phage infectivity, driven by dispersal network shape, resulted in significant local adaptation and maladaptation when using the local vs. foreign definition.
• Local adaptation was not detected with home vs. away or local vs. global definitions under these conditions.

Conclusions:

• Spatial dispersal networks significantly influence parasite local adaptation.
• The shape of dispersal networks can generate spatial heterogeneity in host resistance and parasite infectivity, driving local adaptation.
• The definition of local adaptation is critical for detecting evolutionary patterns, particularly in spatially structured populations.