Adaptation in a spider mite population after long-term evolution on a single host plant

Area of Science:

• Evolutionary biology
• Ecology
• Genetics

Background:

• Long-term adaptation to a single environment may deplete genetic variation, potentially limiting future adaptation to new conditions.
• Understanding the relationship between genetic variation and adaptive potential is crucial for predicting species' responses to environmental change.

Purpose of the Study:

• To investigate whether prolonged evolution in a constant environment affects a population's ability to adapt to novel host plants.
• To determine if genetic variation in the ancestral population predicts evolutionary changes in adaptive traits.

Main Methods:

• Spider mite populations, maintained on cucumber for ~300 generations, were introduced to novel hosts (tomato or pepper).
• Adaptive traits were measured after 15 generations on new hosts.
• A half-sib design was used to assess genetic variation in the base population.

Main Results:

• Juvenile survival and fecundity showed genetic variation and increased on novel hosts, indicating successful adaptation.
• Host choice and developmental time lacked detectable genetic variation and did not evolve.
• Longevity showed genetic variation but did not change, suggesting weak selection.

Conclusions:

• Evolutionary changes in adaptive traits were generally consistent with the patterns of genetic variation present in the ancestral population.
• Long-term adaptation to a constant environment did not preclude adaptation to novel hosts.
• The presence of genetic variation was a key factor in enabling evolutionary responses to new environments.