Robustness is a fundamental property of evolvable biological systems. We can appreciate robustness by simply noticing morphological similarities between individuals of the same species. To understand how a robust pattern is generated during development, we must understand how molecules work together. In this lecture, we will discuss a brilliant example of quantitative biologists’ approach to tackle this challenging question. The authors formulated a mathematical model of the dorsal patterning network of drosophila embryos. They then applied robustness as a selection criterion on simulations of their model, which in turn generated key hypotheses for subsequent experimental validation. Please focus on the investigative process of this study.

*  Before the lecture, please refamiliarize yourselves to Fick’s first and second law of diffusion.

**  Please bring a few pieces of scrap paper and a thick pen to the classroom or to your zoom screens.