Habitat Heterogeneity, Host Population Structure, and Parasite Local Adaptation

Area of Science:

• Evolutionary biology
• Ecology
• Genetics

Background:

• Reciprocal-transplant experiments detect local adaptation (LA).
• Reciprocal cross-inoculation experiments assess parasite adaptation to local hosts, considering co-evolution.
• Host populations may evolve in response to parasite population changes.

Purpose of the Study:

• To determine conditions favoring parasite infectivity to local versus allopatric host populations.
• To model parasite adaptation using genetic matching and host clone selection.
• To investigate the impact of parasite virulence on host diversity and parasite LA.

Main Methods:

• Analytical tools and computer simulations were employed.
• Models assumed parasites require genetic matching with hosts for infection.
• Different host clones were assumed to be favored in different populations.

Main Results:

• Low parasite virulence led to low host diversity and strong parasite LA.
• Intermediate virulence maintained host diversity, reducing or eliminating parasite LA.
• High virulence resulted in oscillatory host dynamics and weak parasite LA.
• Parasite LA strength correlated with host population structure (GST).

Conclusions:

• Parasite local adaptation is influenced by virulence, host diversity, and population structure.
• Reduced infectivity on sympatric hosts, not increased infectivity on allopatric hosts, explains loss of parasite LA.
• Host-parasite co-evolution dynamics are complex and depend on virulence levels.