Loss of electrophoretic variation in serially bottlenecked populations

Area of Science:

• Evolutionary genetics
• Population genetics
• Molecular evolution

Background:

• Founder-flush cycles are crucial for understanding genetic drift and adaptation.
• Bottleneck events can drastically alter genetic diversity within populations.
• Previous theoretical models predicted specific requirements for detecting historical bottlenecks.

Purpose of the Study:

• To investigate the impact of varying bottleneck sizes and founder-flush cycles on genetic variation.
• To compare experimental results with theoretical predictions for detecting historical bottlenecks.
• To assess genetic variation loss and differentiation in housefly populations.

Main Methods:

• Generating experimental bottleneck lines from a single outbred housefly population.
• Subjecting lines to one, three, or five successive founder-flush cycles.
• Assaying electrophoretic variation at four polymorphic loci in 30 individuals per line after each flush.

Main Results:

• Significant losses in genetic variation, particularly allele numbers, were observed across all bottleneck sizes compared to controls.
• Electrophoretic variation generally aligned with neutral theory expectations.
• Differentiation among lines created with 16 pairs of flies was greater than theoretically predicted.

Conclusions:

• Experimental bottlenecks cause substantial reductions in genetic variation.
• The study's findings suggest fewer lines and loci are necessary to detect historical bottlenecks than previously theorized.
• Housefly populations exhibit predictable responses to bottleneck events, with some deviations from neutral expectations.