EVOLUTION AND DEVELOPMENT OF BODY SIZE AND CELL SIZE IN DROSOPHILA MELANOGASTER IN RESPONSE TO TEMPERATURE.

Area of Science:

• Evolutionary biology
• Developmental biology
• Drosophila melanogaster research

Background:

• Body size is a key trait influenced by both genetics and environment.
• Temperature is a significant environmental factor affecting insect development and evolution.
• Understanding adaptive phenotypic plasticity is crucial for predicting species responses to climate change.

Purpose of the Study:

• To investigate the evolutionary and developmental effects of temperature on body size in Drosophila melanogaster.
• To determine the cellular basis of body size changes in response to temperature.
• To assess whether the pattern of plasticity itself evolved.

Main Methods:

• Utilized replicated lines of Drosophila melanogaster evolved for 5 years at two different temperatures (25°C and 16.5°C).
• Measured thorax length and wing area as indicators of body size.
• Analyzed cellular contributions (cell size and number) to overall body size changes.

Main Results:

• Both developmental and evolutionary responses to lower temperatures resulted in increased thorax length and wing area.
• The increase in wing area was primarily driven by an increase in cell size, both developmentally and evolutionarily.
• Developmental responses showed a minor effect of cell number in males, while plasticity patterns did not evolve.

Conclusions:

• Development at lower temperatures leads to larger body and cell size in Drosophila, potentially representing adaptive phenotypic plasticity.
• The evolutionary and developmental mechanisms driving these size changes are linked, with cell size being a key factor.
• The ultimate selective advantage of these temperature-induced responses in Drosophila remains an open question for future research.