These rats got stranded on an island, from the boat they were on that sunk. All they knew was how to walk/run and get their food that was grain, seeds, and vegetables. They had no clue how to survive in this environment.
A lot of rats have died but now slowly but surely the rats are getting adaptations like long nails to climb (to eat coconuts), and learning to swim to eat food like seaweed, coral, and fish. Birds have also been a factor because they have been eating the rats.
Population: 70 rats
3 generations later
Population: 535 rats
The original rats have died out and there is a new species; aguarata ( Spanish for water rat) they have retractable nails to climb trees or defend against birds, they have webed feet and "arms" to help them swim, and can breathe underwater to help them get their food like seaweed, coral , and are now eating fish