His antics in species creation aren't the main plot, but a very entertaining aspect of the story nonetheless.
Either way, this particular duology is one of my all-time favorites. I highly recommend it.
Kobold, have you read Dark Lord of Derkholm by Diana Wynne Jones? The main character's a wizard/biologist/genetics nerd who literally creates hybrid species (such as griffins, pegasi, man-eating tulips) while screwing around with magic and genes.