A species of bird only breeds when it can defend a territory large enough to feed its chicks. A new species of bird arrives on the island and takes over many of the territories. The population of the original species falls, and keeps falling even after the new species has left the island. The remaining birds were tested and no new disease was found. Which explanation is best supported by this information?
The original species had evolved a new adaptation that reduced its breeding
The new species had brought a pathogen that kept killing the original species
The abiotic factors on the island changed while the new species was present
The number of the original species left was too small for them to breed
63 exam-style questions on AQA GCSE Biology 7.1 Adaptations, interdependence and competition, covering 7.1.1 Communities, 7.1.2 Abiotic factors, 7.1.3 Biotic factors, and 7.1.4 Adaptations. Each one has a worked solution and a mark scheme showing where the marks go.