A High throughput method for egg size measurement inDrosophila

Abstract

Many life-history traits are used as proxies of fitness in Drosophila. Egg size is an adaptive trait that can be used for fitness measurement. However, the low throughput of manual measurement of egg size has hampered the widespread use of this trait in evolutionary biology. We established a method for accurate and high throughout measurement of Drosophila egg size using large particle flow cytometry which allows the automated analysis of large particles based on size and optical density. The measurement of egg size is high throughput (average 238 eggs analyzed per minute) and sorting eggs of specific size is efficient (37-75 % efficiency). Using this approach, we showed the natural variation in egg size among strains of Drosophila species. The egg size distribution determined by this approach can be used as a measure of fitness and the reproductive investment in Drosophila. Measurement and sorting by flow cytometer do not decrease the egg viability making it a suitable approach for sorting viable eggs to be used for downstream analyses such as selection experiments.