When I pruned this tree, an Acer Negundo that has grown by itself in a wallnut plantation, I realized that the leaves, contrary to what I am used to see, (and I have pruned many trees), where quite different betwen them. I have more pictures, and expect to put them in a place that can be reached by Internet.
Aceraceae species, in general, have lobed leaves. There are some exceptions, like Acer Negundo, that has composed leaves. The more I look to the pictures I have of these leaves, the more I think Acer Negundo is in the way of evolving versus lobed leaves.
My opinion is that this evolving process is possible, but would like to check it with more informed forum members.
I am not completely in accordance with your statement, that evolution only happens during reproduction, but I do not want to go deep into that debate for the time being.