How Do Invasive Species Destroy Native Species?
If you introduce an exotic species into a non native environment, then it can destroy the native species. But does this always happen through the predator/prey model or can a native species be destroyed by loss of habitat to the invasive or inability to compete for food?
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Competition, predation, disease- the causes are endless. Usually the reason non-native species are such a threat to native species is because native species have not evolved to cope with the non-native ones. A well documented example in Britain is the introduction of the grey squirrel, which is said to have caused our native red squirrel to decrease in numbers and distribution at an alarming rate. Whilst the grey's contribution towards the red squirrel decline remains controversial, there are a number of points to consider.
Red squirrels are one of three squirrel species native to Europe (the others are Persian and Flying squirrels) so they generally occupy a stable ecological niche- as arboreal vegetarians. When the grey squirrel arrived, they took over this niche (not completely, but at least partially), forcing the red squirrels out of their homes and depriving them of food. Because the grey squirrel is a broadleaf specialist, it took over from the red squirrels in these areas, as it was better adapted to survive there.
Britain has one native species of squirrel for a reason- the habitats in Britain are only enough to sustain one species.
In plants, invasive species compete for light and growing space. In animals, they compete for food and living space. When invasive and native species come into contact with one another, the invasive species may also be carrying exotic pathogens and disease that the native species are unused to, so this will kill off large numbers of them.
I would say it could be caused by any of the examples you gave depending on where the animals are compared to each other on the food chain. For example lets say a new species of snake invaded an area, and mouses, snakes, and eagles are the native species of this environment. The predator/prey model would only take effect on the mouses and some snakes that are not as dangerous. The loss of habitat would take effect on some of the snakes that this species cant eat. And the inability to compete for food could effect the eagle because they both eat the mice and there might not be enough for both species.
-Hope this helps:)
Invasive species destroy Native species like this:
1. The species is introduced to the environment.
2. The species start looking for food and land.
3. They find food and land, but then deprive the native species of what they need: Their habitat and food source.
Then the native species either moves or is destroyed in that area.
both...lets say the invasive species is a rat the produces offsrping at 50 babies every birth and they mate 10 times a yr thats 500 rats that came from 1...imagine what her offspring produces...and that can overwhelm the native rat
the prey/predator is simpler...if the predator is invading they dont have something that preys on them since the natives are not adated to this..and same with the prey there is most likely not a predator that will prey on them since they are not "equipped" with the right tools to gobern the species...its all about check and balences