A downhole wellbore isolation tool includes an elastomeric sealing element for engaging a casing member or another tubular member in a wellbore. The isolation tool includes one or more expandable slips for gripping the tubular member and holding the isolation tool in place. The sealing element has an axial end in direct contact with an abutment surface of the expandable slip such that the slip limits, if not eliminates, unwanted extrusion of the sealing element, e.g., upon setting of the isolation tool. The expandable slips may be constructed of a plurality of slip elements, and the elastomeric sealing element may flow into gaps defined between the slip elements when the isolation tool is set. The slip segments and other components of the isolation tool may be constructed of a dissolvable material to facilitate removal of the isolation tool from the wellbore.