Apply precise ecology terms such as population, community, habitat, niche and ecosystem to biological scenarios and data in Cambridge A Level Biology questions, with mark-scheme support.
The natural ecosystem on Hawadax Island in Alaska was disrupted in the 1780s when brown rats, Rattus norvegicus, swam to the island from a sinking ship and then rapidly increased their population size.
The rats occupied a new niche on the island as predators. The rats ate the eggs and chicks of birds such as the black oystercatcher, Haematopus bachmani, and the glaucous-winged gull, Larus glaucescens. These birds make nests, lay eggs and rear their chicks on the beaches of the island.
Define the terms ecosystem and niche.
ecosystem
1 (self-contained unit containing) community of / all / different, organisms / populations / species, and their interactions ;
2 (with the) biotic and abiotic, environment / factors OR
with each other and with the physical environment ;
niche
Conservation ecologists carried out a project to try to restore the natural ecosystem of Hawadax Island. In 2008, they removed all rats from the island.
Before removing the rats, the ecologists measured the abundance of birds, invertebrates and seaweeds on eight of the island's beaches. Seaweeds are large algae that grow attached to rocks on the beach. The ecologists repeated these measurements in 2013 and in 2019, so that they could calculate the percentage change in abundance from 2008.
role / function, of a species within its, ecosystem / habitat ;