EVOLUTIONARY STEPS AND TRANSPOSABLE ELEMENTS IN DROSOPHILA MELANOGASTER: THE MISSING RP TYPE OBTAINED BY GENETIC...

Area of Science:

• Genetics
• Molecular Biology
• Evolutionary Biology

Background:

• The I-R and P-M hybrid dysgenesis systems in Drosophila melanogaster are linked to mobile genetic elements.
• Previous studies suggested P element invasion requires active I elements, a hypothesis not supported by temporal or geographical surveys.

Purpose of the Study:

• To investigate the invasion of Drosophila melanogaster by autonomous P elements in the absence of active I elements.
• To analyze the behavior and cytotype dynamics of newly introduced P elements over 30 generations.

Main Methods:

• Genetic transformation of embryos lacking active I elements and P sequences.
• Gel blotting, in situ hybridization, and genetic experiments to monitor P element behavior.
• Analysis of cytotype switching and copy number changes over generations.

Main Results:

• Successful genetic transformation demonstrating P element invasion without active I elements.
• Slow cytotype switch from M to P, with P element copy number increasing to approximately 25.
• Generated RP lines induce P-M hybrid dysgenesis while retaining the R cellular state.

Conclusions:

• P elements can invade Drosophila melanogaster genomes independently of active I elements.
• The new mobile element combination (RP lines) creates strong reciprocal post-zygotic isolation with IM strains.
• This genomic incompatibility represents a potential initial step toward speciation in Drosophila.