Aliens have discovered a new planet in its Goldilocks zone that (other than gravity) is the same in every way to Earth. They wish to bring Earth animals into the planet to create their own ecosystem test, but there exists a problem, this new planet (named Terra) has a gravity 72% that of Earth. The life that currently exists on Terra is comparable to very basic plants and animals but it is very early life. They have enlisted their greatest minds to figure out what animals to choose. What Earthen animals would be to quickest able to adapt to this new low gravity world?
I would say almost any animal.
smaller animals are "less susceptible" to gravity changes since being smaller they have a lower volume/surface ratio, so with a 0.72 g they would barely notice.
water dwelling animals would also barely notice since they live inside water where buoyancy almost negate their weight.
bigger animals would indeed notice and with time they would be subject to some changes. However an adult elephant that weights 7000 Kg on Earth would be about 5000 Kg on Terra; not a very big difference. They are going to be ok.
Birds. There entire existence depends on them overcoming gravity. In this new existence you've actually made their job easier because now gravity is weaker so it takes less effort for them to overcome it. Depending on how low your gravity was birds that have wings but aren't able to fly such as chickens would it be able to gain the ability. Assuming there were no other changes just a slight decrease in gravity and I think birds with not only adapt and survived but I think they would thrive.