Optimization is just a tool for design
What’s the relationship between these two disciplines, and teams? One clearly supports the other.
Design comes first. Without a complete, working design, there’s nothing to optimize.
Furthermore, while optimization and experimentation are a way to measure the impact of a design and ultimately improve it, they’re just one of many ways to do that.
In fact, you need to reach a fairly high level of traffic (technically conversions) before you can even begin to do A/B testing. Until you reach that point, optimization isn’t even in the picture.
So the optimization team provides feedback and metrics that inform decisions about the user experience, but it’s the design team that creates it in the first place, and uses a variety of research techniques - not just experimentation - to refine it.
(This post written by #teamdesign)