Increasing evidence suggests that adaptive evolution can be rapid enough to affect contemporary ecological dynamics. As ecological processes can drive adaptive evolution by modifying fitness landscapes, ecological and evolutionary processes can interact in the same timescale (i.e., eco-evolutionary dynamics). To understand the potentially complex dynamics, we constructed mathematical models and analyzed eco-evolutionary feedbacks. We showed that (1) detailed mechanisms of trait adaptation can be important for understanding eco-evolutionary dynamics, and (2) rapid evolution can promote species coexistence via various mechanisms including intraspecific adaptation load, relative nonlinearity, and the temporal storage effect. These theoretical predictions will be useful for future empirical studies.