Does a living trust affect the right of survivorship in a joint tenants ownership?

While you used the term "joint tenancy", sometime this term is used loosely to describe when property is owned by more than one person, when in actuality there are several forms of tenancy in which people can jointly own property.  If property is owned by a joint tenanct, it means that they each own an undivided interest in the property.  It is like the property is owned by a separate entity, like a corporation, which in turn is owned by two people equally.  When one joint tenant dies, the asset held in joint tenancy becomes the sole property of the other joint tenant, regardless of a living trust.  However, if the property is held as tenants in common, each party owns a 1/2 interest, and that 1/2 interest passes according to a will, or in this case, the trust instrument.