Question

which factor does not affect species richness on islands? longitude of island latitude of island distance from mainland available niches

Explanation:

Species richness on islands is affected by latitude (influences climate and habitat), distance from mainland (affects colonization), and available niches (habitat diversity). Longitude has no direct impact on species richness on islands as it mainly relates to time - zones and not ecological factors that drive species richness.

Answer:

Longitude of island