The Canadian Association of University Teachers is “surprised and disappointed” by the Canadian government’s decision to appoint President Shirley M. Tilghman of Princeton University as co-chair of the selection board for the Canada Excellence Research Chairs. According to a letter sent Thursday night to the minister of science, the union says there’s no shortage of distinguished academics in Canada who could have filled the position, which will help pick the winners of the well-financed, prestigious research chairs. Each of the chairs is worth up to $10-million. The appointment was quietly made last November but became publicly known Thursday when the minister issued a release congratulating Ms. Tilghman, who is a Canadian citizen.