Accumulation of transposable elements in the genome of Drosophila melanogaster is associated with a decrease in...

Area of Science:

• Genetics
• Evolutionary Biology
• Molecular Biology

Background:

• Isogenic laboratory strains of Drosophila melanogaster (2b and Harwich) exhibit varying transposable element (TE) copy numbers.
• Transposable elements are DNA sequences capable of changing their position within a genome, potentially affecting host gene function and genome stability.

Purpose of the Study:

• To investigate the correlation between transposable element (TE) copy number and fitness in Drosophila melanogaster.
• To determine the impact of TE accumulation on fitness components, specifically egg hatchability.

Main Methods:

• Utilized two isogenic Drosophila melanogaster strains (2b and Harwich) with divergent TE copy numbers.
• Analyzed the relationship between TE copy number and fitness metrics, including egg hatchability.
• Estimated the average deleterious effect of individual TE insertions on fitness.

Main Results:

• A significant negative correlation was observed between TE copy number and fitness/egg hatchability in the 2b strain, which had a larger divergence in TE copies.
• No significant correlation was found in the Harwich strain, which exhibited a smaller divergence in TE copies.
• The average deleterious effect of a single TE insertion on fitness was estimated at 0.004.
• Both homozygous and heterozygous TE insertions demonstrated detrimental effects on fitness.

Conclusions:

• Increased transposable element (TE) load negatively impacts Drosophila melanogaster fitness and reproductive success.
• The magnitude of TE copy number divergence influences the detectability of deleterious effects.
• TE insertions, regardless of zygosity, contribute to reduced fitness, highlighting their potential evolutionary cost.