Great mockup! I really like the part at the top, but would probably adjust it to also display the name of each species above (or below) the portrait for new players. The credits are a nice touch, but may want to switch it to +5000 [8700] to keep it consistent with the race changes. I would consider dropping the solar date as I don't think that's particularly needed on the screen (but it does look nice).
There's also the tricky aspect of displaying when the relationship between two species changes as a result (e.g. gifting technology via another race), but that's pretty rare and can probably be relegated to text. Nice work!