We study the genealogy of a solvable population model with N particles on the real line which evolves according to a discrete-time branching process with selection. At each time step, every particle gives birth to children around a times its current position, where a > 0 is a parameter of the model. Then, the N rightmost newborn children are selected to form the next generation. We show that the genealogical trees of the process converge to those of a Beta coalescent as N → ∞. The process we consider can be seen as a toy-model version of a continuous-time branching process with selection, in which particles move according to independent Ornstein-Uhlenbeck processes. The parameter a is akin to the pulling strength of the Ornstein-Uhlenbeck motion.