Explain how competition can affect an organism's niche.

In interspecies competition, two species use the same limited resource. Competition has a negative effect on both of the species (-/- interaction). Two species whose niches overlap may evolve by natural selection to have more distinct niches, resulting in resource partitioning.

maritime tropical may be your answer.

on island x the species needed to adapt because they were being subject to predators which didn't inhabit island y.