So I have a character idea for a Druid.....

[NecroDancer]

I was thinking about making a druid character for a one shot that's coming up, I wanted to make my Druid slightly more unique fluff wise by making him into a biologist that studies the living world and sometimes makes "improvements" to himself in order to "evolve" to a higher understanding. The Wild Shape ability and Polymorph spell works pretty well for this character's fluff but I was wondering if there was a prestige class/base class/template that improves Wild Shape or the Polymorph spell (or just gives me more "evolution" themed powers).

Thanks for the help.

[Fouredged Sword]

You could take it in a crazy direction with Fleshwarper, using grafts and such to "evolve" life. You need to take the feat that grants a few 0th level spells and obtain familiar, but you can qualify.

[Goaty14]

Nature's Warrior and Warshaper come to mind.

[Zombulian]

You could take it in a crazy direction with Fleshwarper, using grafts and such to "evolve" life. You need to take the feat that grants a few 0th level spells and obtain familiar, but you can qualify.

This is what I came here to say, but I have a few more things now that I think about it.
Adding "alterations" like you said sounds less like Wildshape to me and more like the Shapeshifter Druid ACF.
There's also Master of Many Forms (CAdv), and the Flux Adept, Shaper of Form, and Osteomancer (Dragon Compendium).

[Gruftzwerg]

fluff wise by making him into a biologist that studies the living world

While it has nothing to do with wild shape, "Knowledge Devotion" would fit the fluff. The feat lets you roll a knowledge check depending on enemy type and gives you a bonus to hit & dmg for that encounter.