Ecological feedbacks and the evolution of resistance.

Area of Science:

• Ecology
• Evolutionary Biology
• Parasitology

Background:

• Parasites are known to influence host diversity, with a particular interest in their potential to increase it.
• Host resistance diversity to parasites is a key factor in understanding host-parasite dynamics.
• Theoretical frameworks predict various selection types exerted by parasites on host populations.

Purpose of the Study:

• To review the diverse ways parasites can influence host resistance diversity.
• To explore theoretical predictions of parasite-mediated selection on host diversity.
• To examine empirical evidence for different selection types and their spatiotemporal variation.

Main Methods:

• Literature review of theoretical and empirical studies on parasite-mediated selection.
• Analysis of theoretical predictions including negative frequency-dependent selection (NFDS), disruptive selection, directional selection, and stabilizing selection.
• Synthesis of empirical evidence from natural populations demonstrating these selection types and their variation.

Main Results:

• Parasites can exert NFDS and disruptive selection, increasing host diversity, as well as directional and stabilizing selection, decreasing diversity.
• Empirical evidence supports the occurrence of all predicted selection types in natural populations.
• Spatiotemporal variation in parasite-mediated selection is observed, influenced by environmental factors and resistance trade-offs.

Conclusions:

• Spatiotemporal variation in parasite-driven evolution is likely common and influenced by ecological factors.
• Trade-offs associated with host resistance critically determine the type of parasite-mediated selection.
• Further research on the feedback between ecological dynamics and host-parasite evolution is warranted to understand variations in parasite effects on host diversity.