Quadratic perturbations of a quadratic reversible Lotka-Volterra system with two centers

This paper is concerned with the bifurcation of limit cycles from a quadratic reversible Lotka-Volterra system with two centers of genus one under small quadratic perturbations. It shows that the cyclicities of each period annulus and two period annuli of the considered system under small quadratic perturbations are two, respectively. This not only gives at least partially a positive answer to an open conjecture, but also improves the correspondingresults in the literature. In addition, we present the configurations of limit cycles of the perturbed system as (2, 0), (1, 1), (1, 0), (0, 2), (0, 1) and (0, 0), where (i; j) indicates that the perturbed system has i limit cycles surrounding the positive singularity while it has j limit cycles surrounding the negative one.