Combining experimental evolution and field population assays to study the evolution of host range breadth.

Area of Science:

• Evolutionary Biology
• Ecology
• Animal Behavior

Background:

• Host-specific adaptation often leads to trade-offs, influencing the evolution of specialists (narrow host range) and generalists (wide host range).
• The two-spotted spider mite (Tetranychus urticae) is a model organism for studying host range evolution and specialization.

Purpose of the Study:

• To investigate how adaptation to a specific host impacts host range evolution and performance across different hosts.
• To determine if experimental evolution can reliably predict field observations of host range adaptation.

Main Methods:

• Laboratory experiments using field populations of Tetranychus urticae sampled from tomato, citrus, and Nerium oleander.
• Experimental evolution selecting mite lines on each of the three host plant species.

Main Results:

• Mite populations adapted to tomato could only exploit tomato, while citrus-adapted mites exploited citrus and tomato, and Nerium-adapted mites exploited all three hosts.
• Wider host ranges in citrus and Nerium-adapted mites came at the cost of reduced performance on non-native hosts.
• Experimental evolution mirrored field population patterns, indicating adaptation to new hosts can expand range but decrease performance on others.

Conclusions:

• Adaptation to a new host species can lead to a wider host range but with decreased performance on ancestral or other hosts.
• Experimental evolution is a reliable method for studying host range evolution and associated performance trade-offs in the field.