Islands Flashcards
Define rafting
the technical name for the process by which non-flying animals end up marooned on remote islands. Mammals do not raft well (humans excepted), but reptiles do.
What are the main problems of survival for colonisers?
Mostly survival as there are few or no competitors and it’s a predator-free system
Why do we get endemics on islands?
1) Small genetic input (the founder effect) - entire populations have the genetic make-up of the founding couple
2) Isolation - no connection with mainland gene pool to dilute changes
3) Unusal selection pressures
Name two UK native species that are island endemics.
Skomer vole and St Kilda vole
Name two endemic UK insects.
The Lundy cabbage beetle and the Lundy weevil, both feed on the endemic Lundy cabbage
Hawaii makes up ____% of US land area but has ___% of endangered species in USA and ____% of its extinctions
Hawaii is 0.3% US land area but has has 40% of endangered spp in USA and 75% of its extinctions).
Explain the island rule
Birds or insects may become giant or flightless, often mammals become dwarf
Name a hominin that dwarfism applied to
Homo floresiensis
It was less than 1m tall
What happened to the St Helena Giant Earwig?
Introduced species probably hunted it to extinction (mice and centipedes)
Isolated island endemics experience lifestyle changes. Give two examples.
The Laysan finch is a honeycreeper but has been seen sucking blood of albatrosses.
Hawaii has caterpillars that catch flying insects
Describe a moth endemic to Marion island.
The Marion island flightless moth caterpillars need albatross nests for warmth and are endangered by introduced mice and albatross decline
Sine mice have appeared, not just are caterpillars rarer, they are also much smaller. Selective removal of the large edible ones?
Give an example of a mouse becoming giant.
Gough Island sea birds are now predated – by ‘giant’ mice
House mice got ashore 150 years ago with whalers, as normal mice. They evolved to be 2* larger than normal body weight, and co-operative predators that eat an albatross chick (300* body weight) alive.
Describe an odd island endemic plant, native to the Indian ocean islands
Indian ocean islands hold Pisonia grandis, a tree whose large sticky flowers sometimes catch nestling terns. The tree benefits from their nutrients as they decay - carnivorous flowers!
Why are almost all island endemics automatically a conservation worry?
Almost all island endemics are automatically a conservation worry due to small geographical range.
Also, they have no fear of predation, they tend to be K selection (few large offspring) and have no tolerance for disease,
A consistent pattern is that remote islands used to hold giant flightless birds, until humans arrived. List four examples.
Geese in Hawaii
Moas in New Zealand
Kakapos in New Zealand
Giant owls in the bahamas.
When and why did the dodo of the forests of Mauritius go extinct?
Went extinct in 1681 partially due to being eaten by us but also monkeys and pigs eating the eggs and young
What is the kakapo?
the largest parrot in the world. Also the only nocturnal parrot, only flightless parrot, only parrot to operate a lekking system. It is endemic to New Zealand, and is utterly unable to cope with cats or ferrets. The NZ government keeps a stud book of all known kakapos – its population returned to 100 in March 2009
Which species of flightless bird is the only organism to be entirely wiped out by a single organism (Tibbles)?
The Stephen’s Island Wren
Why are rats bad for island endemics?
Long known to swim ashore and ruin island systems. Nesting seabirds get eaten, live or dead. Researchers have been forced to abandon tents due to rat attacks.
What is the biggest single killer of native Hawaiian birds?
The biggest single killer of native Hawaiian birds came from one barrel of spoiled water thrown overboard in the 1880s. This introduced mosquitoes, which vectored avian malaria. Now the surviving endemic birds are in high, cold mosquito-free forests.
What has been the result of the introduction to Guam of a Solomon-island bird eating snake that stowed away with the US military?
The woods are now full of spiders’ webs as there are no birds to eat spiders of snap their webs (because almost all endemic bird life on Guam has been wiped out by the snake)
Why are snails of the genus Partula almost unique?
They give birth to live young
Why was introducing giant African land snails as food to the pacific islands bad for /Partula/ snails?
The giant African land snails devastated crops so predatory snails were introduced to control the pest but these didn’t touch the giant African snails, but did prey on Partulas!
_____% of all island endemic plants in the IUCN red data book are mentioned as threatened by ______
26% of all island endemic plants in the IUCN red data book are mentioned as threatened by goats.
Why shouldn’t you stop hunting goats if you’re trying to get rid of them?
Don’t stop! Pinta island (Galapagos) had 10,000 goats. These were hunted down to 3 animals, then left. 12 years later there were 20,000 goats, albeit very inbred.
What happened after cats were exterminated (to protect birds) on Macquarie island?
The rabbit population exploded and ruined much of the ground vegetation
When did Polynesians arrive in Easter island? What did they do with the land?
Around 1200 AD
They cut down all the trees to make boats or Moai (giant statues)
Once the trees were gone from Easter island, what happened?
Once the trees were gone, the islanders were isolated and stuck. They destroyed the onshore seabird colonies (seals too), then the bird colonies on swimmable offshore islands. Midden contents show a rapid drop in fish and bird bones around the 17th century. Half the native plant species went extinct.
This phase left the island with people, chickens, a few domestic plants - and nothing else. Wild biodiversity was all but destroyed.
