You could just create another legend item in your print layout and adjust them manually.
When you create your legend in the print layout with Add Item > Add Legend, on the right side of the print layout window, find item properties. Then scroll down to legend items and uncheck the auto update box. Turn off all but "genetic sampling locations"
After I uncheck auto update, I can remove stuff from the legend with the red minus button below. Here is the legend items box after removing all but one layer:
Now if you draw a legend on the print canvas, you'll only have the one item in it.
Repeat the process, this time only include your "former range" layer. Now draw another legend on the print layout and you'll have something like this:
I highlighted both of them to prove the point that they are separate legend items on the print canvas. Now you can move them around until they are in alignment and look good on the final layout.