Trait-specific consequences of inbreeding on adaptive phenotypic plasticity

Area of Science:

• Evolutionary Biology
• Genetics
• Environmental Science

Background:

• Environmental changes can induce adaptive phenotypic responses in organisms.
• Inbreeding can interact with environmental stress, potentially reducing fitness in inbred individuals.
• A reduced capacity for phenotypic plasticity in inbred individuals is a proposed explanation for these fitness effects, but it remains largely untested.

Purpose of the Study:

• To investigate whether inbreeding reduces phenotypic plasticity in response to environmental stress.
• To test the hypothesis that reduced plasticity explains inbreeding-environment interactions impacting fitness.

Main Methods:

• Replicate Drosophila melanogaster populations were reared for 25 generations under conditions mimicking natural inbreeding (small population size).
• Inbred and control (large population size) populations were exposed to three developmental temperatures: benign, low-margin, and high-margin.
• Phenotypic traits including abdominal pigmentation, wing size, and wing shape were measured across the different temperatures.

Main Results:

• No significant differences in phenotypic plasticity for pigmentation or wing size were observed between inbred and control populations.
• Inbred populations exhibited significantly higher phenotypic plasticity in wing shape compared to control populations across the tested temperatures.
• Norms of reaction for the control populations indicated adaptive phenotypic responses to temperature changes.

Conclusions:

• A reduced ability to mount an adaptive phenotypic response to environmental changes is not a universal consequence of inbreeding.
• The results suggest that reduced phenotypic plasticity is not a general explanation for the negative effects of inbreeding on fitness components in interaction with the environment.