Does plasticity enhance or dampen phenotypic parallelism? A test with three lake-stream stickleback pairs

Area of Science:

• Evolutionary biology
• Ecology
• Genetics

Background:

• Disentangling genetic and environmental influences on phenotypic variation in wild populations is challenging.
• Phenotypic plasticity's role in promoting or hindering parallel evolution is often overlooked.
• Adaptive divergence studies benefit from comparing wild and controlled environmental conditions.

Purpose of the Study:

• To assess the genetic and plastic contributions to adaptive divergence in lake-stream stickleback populations.
• To investigate how phenotypic plasticity influences phenotypic parallelism.
• To compare plasticity prevalence across different watersheds.

Main Methods:

• Common-garden experiment with three independent lake-stream stickleback population pairs.
• Evaluation of genetic basis versus plastic basis for adaptive divergence.
• Analysis of plasticity's enhancing or dampening effects on phenotypic parallelism.

Main Results:

• Lake-stream differences in most traits were primarily genetic, with significant plastic contributions in several traits.
• Phenotypic plasticity was more pronounced in one watershed compared to others.
• Plasticity generally enhanced phenotypic parallelism, but had a dampening effect in some instances.

Conclusions:

• Genetic and plastic factors play complementary, adaptive roles in stickleback phenotypic parallelism.
• Common-garden studies are crucial for formally evaluating plasticity's impact on parallel evolution.
• Understanding both genetic and plastic influences provides a more complete picture of adaptive divergence.