How do I translate an expression tree of one type to a different expression type?

If I have two nearly identical classes Animal and AnimalViewModel and an expression tree related to the viewmodel, how can I translate it to Animal?

public class Animal
{
   public string Species { get; set; }
   public string Name { get; set; }
   public string Sound { get; set; }
}
public class AnimalViewModel : ViewModelBase
{
   public string Species { get; set; }
   public string Name { get; set; }
   public string Sound { get; set; }
}

How can I translate an Expression<Func<AnimalViewModel,bool>> to Expression<Func<Animal,bool>>?

public static Expression<Func<Animal,bool>> Translate (Expression<Func<AnimalViewModel,bool>> expression)
{
  // What goes here?  I assume I have to traverse the tree somehow.
}