Drosophila Wing Vein Genetics Across Two Cities

ISEF Category: Cellular and Molecular Biology

Subcategory: Genetics  ·  Difficulty: Advanced  ·  Setup: University Lab  ·  Time: Full Year

The Hook

Fruit flies can pack a lot of genetics into a tiny body. One wing can reveal changes that affect development, anatomy, and inheritance. If you compare flies from two cities, you may find patterns that are invisible by eye but clear in images and DNA. That gives you a real chance to study natural variation instead of just repeating a textbook mutant lab.

What Is It?

Drosophila wing veins act like a built-in map of development. The pattern is shaped by genes, so small genetic differences can change where veins form, how thick they look, or whether a vein is partly missing. You can think of the wing like a printed circuit board. The veins are the lines, and genes help decide where those lines go.

This project asks whether wild flies from different cities show different wing-vein patterns, and whether those patterns line up with variation in a candidate gene. You would collect flies, photograph their wings, and score the shapes with image analysis. Then you would compare that phenotype data with PCR and Sanger sequencing results from the same flies. The ML part can help you sort wings faster or quantify shape traits more consistently than visual scoring alone.

Why This Is a Good Topic

This is a strong science fair topic because it connects a visible trait, a gene, and a real population difference. You can measure the wing phenotype, compare groups, and test whether DNA variation tracks with anatomy. That makes the project more than a fly collection exercise. You can also learn genetics, image analysis, statistics, and how to handle noisy data from real organisms.

Research Questions

• How does wing-vein shape vary between wild Drosophila collected from two cities?
• What is the effect of city of origin on the frequency of wing-vein abnormalities?
• Does candidate gene sequence variation differ between flies from the two cities?
• To what extent do image-based wing measurements predict manual phenotype scores?
• Which wing-vein traits show the strongest association with candidate gene variants?
• To what extent does sex or body size change the wing-vein phenotype in wild flies?

Basic Materials

• Fly collection vials and baited traps or other approved collection method.
• Fine paintbrush or aspirator for handling flies.
• Stereo microscope or dissecting microscope.
• Smartphone or digital camera with a stable stand.
• Transparent slide holders or mounting materials for wings.
• Image analysis software, such as ImageJ.
• Notebook or spreadsheet for phenotype scoring.
• Gloves, ethanol, and disinfectant for cleanup and sample labeling.

Advanced Materials

• PCR thermocycler.
• Micropipettes and filtered tips.
• Fly DNA extraction kit or validated low-input extraction reagents.
• Agarose gel electrophoresis setup.
• Mail-in Sanger sequencing service.
• High-resolution microscope camera.
• Computer with ML software for image classification or landmark analysis.
• Statistical software for genotype-phenotype association testing.

Software & Tools

• ImageJ: Measures wing-vein distances, angles, and shape features from wing images.
• Python: Organizes images, extracts features, and supports ML models for phenotype scoring.
• R: Runs statistical tests, plots city-to-city differences, and checks genotype-phenotype links.
• Google Colab: Lets you train simple ML models without installing software on your own computer.
• SnapGene Viewer: Helps you inspect PCR products and compare candidate gene sequences.

Experiment Steps

1. Define one wing-vein trait set, one candidate gene, and one comparison between the two city populations.
2. Plan how you will collect, label, and separate flies so each specimen keeps a clear origin record.
3. Design a photo workflow that keeps wing images consistent enough for measurement and ML training.
4. Choose the phenotypes you will score by hand first, then decide which features the software should learn.
5. Build a genotype plan that matches each sequenced fly to its image and phenotype record.
6. Set your analysis plan before collecting data, including controls, sample size goals, and the statistical test for group differences.

Common Pitfalls

• Mixing up collection sites or sample IDs, which breaks any city-to-city comparison.
• Photographing wings at different angles or lighting conditions, which makes vein measurements drift.
• Using a candidate gene with weak or no relation to wing development, which leaves the DNA data uninformative.
• Scoring malformed wings by eye without a clear rubric, which makes the phenotype data noisy.
• Training an ML model on too few images, which makes it memorize the training set instead of learning wing shape.

What Makes This Competitive

A competitive version of this project would do more than compare two piles of flies. You would need a clean phenotype pipeline, a clear candidate-gene rationale, and enough samples to support real statistics. Strong projects also test whether image-based ML scoring agrees with human scoring and whether genotype explains any of the wing differences. That kind of layered analysis can turn a neat observation into a serious genetics study.

Project Variations

• Compare wing-vein variation in indoor versus outdoor wild Drosophila instead of two cities.
• Test whether one ML model can classify subtle wing defects better than a human scorer.
• Sequence a different candidate gene linked to wing development and compare its variants across populations.

Learn More

• FlyBase: Search this Drosophila genetics database for gene functions, mutant phenotypes, and pathway links.
• NIH PubMed: Search review articles on Drosophila wing development, natural variation, and genotype-phenotype association.
• NCBI Gene: Look up candidate genes and read their annotated functions and sequence records.
• ImageJ Documentation: Find free guides for measuring distances, angles, and shape features in biological images.
• MIT OpenCourseWare: Search for genetics and molecular biology course materials that explain PCR, sequencing, and inheritance.
• USDA ARS Drosophila Resources: Use government and research references for fly biology, collection, and laboratory handling.