Can evolution of sexual dimorphism be triggered by developmental temperatures?

Area of Science:

• Evolutionary Biology
• Environmental Science
• Genetics

Background:

• Sexual dimorphism evolution requires specific genetic conditions rarely observed.
• Rapid evolution of sexual dimorphism suggests environmental sensitivity.
• Limited research exists on how environmental variation affects the genetic basis of sexual dimorphism.

Purpose of the Study:

• To investigate the environmental sensitivity of the genetic background of sexual dimorphism.
• To determine the impact of developmental temperature on heat shock tolerance and its genetic basis in Drosophila melanogaster.

Main Methods:

• Utilized a nested full-sib-half-sib breeding design in Drosophila melanogaster.
• Exposed developing flies to four distinct temperature treatments: constant 25°C, constant 30°C, cycling 25°C mean, and cycling 30°C mean.
• Assessed adult heat shock tolerance and estimated heritabilities and genetic correlations between sexes.

Main Results:

• Developmental temperature significantly influenced sexual dimorphism in heat shock tolerance.
• Female heritability for heat shock tolerance decreased under hotter and cycling temperatures.
• Genetic variation for heat shock tolerance was largely uncorrelated between sexes, enabling independent evolutionary trajectories.

Conclusions:

• Environmental conditions during development can profoundly influence the genetic architecture of sexual dimorphism.
• The findings support the hypothesis that environmental factors shape the evolution of sex-specific traits.
• Independent evolution of traits between sexes is facilitated by orthogonal genetic variation, particularly under varying environmental conditions.