A free boundary problem of prey-predator model with variable intrinsic growth rate for predator

Abstract: This paper deals with a free boundary problem of the Lotka-Volterra type prey-predator model with variable intrinsic growth rate for predator over a one dimensional habitat, in which the free boundary represents the spreading front and is caused only by the prey. In this problem it is assumed that the species can only invade further into the new environment from the right end of the initial region, and the spreading front expands at a speed that is proportional to the prey's population gradient at the front. Moreover, the variable intrinsic growth rate $r(t,x)$ is positive in pointwise but may be very small as $t\to\infty$ or $x\to\infty$. The main objective is to realize the dynamics/variations of prey, predator and free boundary. We first study the long time behavior of $(u,v)$ for the vanishing case ($h_\infty<\infty$). Then we find the criteria for spreading and vanishing. At last, the long time behavior of $(u,v)$ for the spreading case ($h_\infty=\infty$) is discussed. Theorems 2.2, 2.3 and 4.1 together establish a spreading-vanishing dichotomy. Moreover, our model exhibits very different properties from the free boundary problems of prey-predator model in which the free boundary is caused only by the predator or by both prey and predator.