Protections the ozone layer
Maintaining animal and human food chain
Preserving potable water and making efficient use of non renewable resources
Reproduce and soon take over the island with the ancient power if iguanas, jk jk
though they will reproduce it will depend on the food source and if there is a food source since they are introduced to a new environment they most likely won't have any predators and can eat and move freely as much as they want to.
I hope this helps
Hope this helps!
https://www.nature.com/scitable/topicpage/genetic-mutation-1127
50% because they each get half from their mom and half from their dad