Spreading with two speeds and mass segregation in a diffusive competition system with free boundaries

We investigate the spreading behavior of two invasive species modeled by a Lotka–Volterra diffusive competition system with two free boundaries in a spherically symmetric setting. We show that, for the weak–strong competition case, under suitable assumptions, both species in the system can successfully spread into the available environment, but their spreading speeds are different, and their population masses tend to segregate, with the slower spreading competitor having its population concentrating on an expanding ball, say Bₜ, and the faster spreading competitor concentrating on a spherical shell outside Bₜ that disappears to infinity as time goes to infinity.