Selected Habitats: Oceanic Islands Flashcards
What is an oceanic island?
Islands that are sufficiently isolated from major land masses so it is difficult for species to colonise
How were most oceanic islands formed?
Volcanic eruptions or the build-up of sand from nearby corals
What species are most likely colonise oceanic islands easily?
Marine species
Sea birds
Plants with floating seeds
What species colonise oceanic islands by chance?
Tortoises
Terrestrial birds
How can tortoises end up on oceanic islands?
By being carried on drifting logs
How can terrestrial birds end up on oceanic islands?
If they are carried by strong winds
What will happen to species that colonise the oceanic islands?
They will gradually evolve to occupy the available ecological niches
How does evolution create unique species?
As the conditions that affect selection pressure, and the characteristics that provide a survival advantage are different in different places
Why might biodiversity by low on oceanic islands?
Because they are difficult to colonise
One or more groups of organisms may not be present
Why aren’t many mammals found on oceanic islands?
Its hard for them to colonise isolated islands
What sort of mamamals will colonise oceanic islands?
Seals and bats but not terrestrial mammals
What sort of islands will have mammal species?
Those that were previously attached to continents
What is an example of where mammals are present on oceanic islands after disconnecting from continents?
Lemurs in Madagascar
Why are oceanic islands important?
The high proportion of endemic species increases the possibility of the discovery of unique medicines or features for biomemetics
How were species exploited on oceanic islands?
Species were heavily exploited for food
What species found on oceanic islands have been exploited for food?
Dodo
Giant tortoises
Marine turtles
How can introduced predator species affect oceanic islands?
Due to the lack of mammal predators the indigenous species are not adapted to survive predatory species
What are some examples of predatory species on oceanic islands?
Rats form shipwrecks
Cats that were introduced as pets
What is the problem with introduced herbivores?
They destroy the indigenous plant communities
What are some examples of introduced herbivores on oceanic islands?
Goats
Rabbits
What are the problems with introduced plants on oceanic islands?
They may outcompete the indigenous vegetation
what is an example of how an oceanic island was affected by an introduced pathogen?
Avian malaria was introduced Hawaii which killed many bird species
How will climate change affect the spread on Avian malaria?
Usually not present above 1500m due to the cold but with rising temperatures it may be able to spread to higher altitudes
What causes habitat destruction on oceanic islands?
Urban, agricultural and tourist developments
How do the oceans threaten oceanic islands?
Sea level rise
How can oceanic islands be conserved?
Usually by attempts to stop or reverse the damaging effects of human action
What has been the biggest single action to conserve endemic species on oceanic islands?
The eradication of introduced species
Rats, goats, cats and rabbits
How many islands have introduced species successfully been eradicated from?
Nearly 1000
