The Stark Divide. Liminal Sky: Ariadne Cycle, #1

Some stories are epic. The Earth is in a state of collapse, with wars breaking out over resources and an environment pushed to the edge by human greed. Three living generation ships have been built with a combination of genetic mastery, artificial intelligence, technology, and raw materials harvested from the asteroid belt. This is the story of one of them-43 Ariadne, or Forever, as her inhabitants call her-a living world that carries the remaining hopes of humanity, and the three generations of scientists, engineers, and explorers working to colonize her.
From her humble beginnings as a seedling saved from disaster to the start of her journey across the void of space toward a new home for the human race, The Stark Divide tells the tales of the world, the people who made her, and the few who will become something altogether beyond human. Humankind has just taken its first step toward the stars.