I read a novel some time back in the 1980s about a planet whose sun begins emitting more radiation than it had been (ionizing stuff, not merely light.) Pre-nova or something.
The higher radiation levels cause mutations in the plants and creatures living on the planet. Evolution proceeds at a much higher rate there than it should have.
Intelligent beings eventually arise, and take advantage of the high radiation and mutation rates to breed animals for specific tasks. I remember one chapter involved the "captain" of a barge like cargo ship. The ship was one of a long line of critters bred over generations to make better and better ships. The ships were not made of the animal, rather the animal was the ship - living. Like you can ride a horse, the captain could guide his living ship through the swampy rivers.
The story was told in sections, from the first change in the sun causing the first mutations, through the development of intelligence, science, and technology, to the realization that the sun was going to go nova and that the "people" were going to have to leave the planet before the sun exploded. Not that the sun was going to go "spung" tomorrow, but at some indefinite time in the future - tens of thousands or millions of years rather than the billions we currently expect our sun to last.
The final chapter ends with the launch of a space ship "made" of an animal bred for the purpose. There's mention of the organs needed for high pressure pumps. I think it pumped reaction mass directly rather than using rockets. No flames, just one more heck of a lot of liquid pumped at high pressure and velocity.
The planet itself is short on metals. At one point I remember mention of the development of electricity being delayed because they had to develop room temperature, biologically made superconductors to be able to make practical use of electricity.
I can't remember the name of the novel or the author. I know I don't have a copy of it here. I most likely read a copy that my father had. It was probably written in the late 1970s or early 1980s.
Has anyone ever read this book? What's its name, and who wrote it?
This question on "Worldbuilding reminded me of the story. I was going to suggest the asker read the novel I've got in mind, but I can't recall the name.