User research is a critical to the design process. But, In an early stage software startup, designers and product managers often share the role. Here’s how I’ve seen the role been split up.

• A UX designer will split their time in conducting research. Product plays a supporting role, often booking interviews and capturing insights. This can only happen when design has the capacity, AND there’s enough interest from one UX designer to play this role.
• Product does most of the research, because design is focused on the critical path of prototyping and building the product. Product steps in because there’s no capacity. This happens quite often, perhaps more so than the first case.
• Design does attitudinal research (understanding why people would use your product), and product focuses on behavioural research (how people use it - through A/B testing etc). This split can carry through for a long time, even when there are dedicated researchers on the team.

At the end of the day, what matters most is that you understand who your users are, the problems they’re having, and how well your solution is helping. The role abstractions are helpful, but every company answers these questions in a different way.