Introduced Species Can Threaten Biodiversity Because They Can
Threats to Biodiversity: Invasive Species
Invasive species are the second largest threat to biodiversity after habitat loss. An invasive species is a species that is not native to a particular area, but arrives (usually with human help), establishes a population, and spreads on its own. Invasive species have much larger impacts on an ecosystem than other species. They have a disproportionate effect, which is what makes them and then harmful. Curlicue down to meet what these suckers do.
Not all species that arrive in a new location go invasive—in fact, most do not. Lots of garden plants are imported from other places, and fifty-fifty if they sometimes grow wild, they do not achieve large populations and exercise not brand a huge splash on native species survival. These are merely called not-native or introduced species. The introduced species that do become invasive are the ones that cause large problems.
Some places are particularly vulnerable to invasive species. Islands ordinarily have lots of endemic species and few large grazers or predators; this makes island species more at hazard when non-native species are introduced.
Other places have very depression rates of species invasion, commonly because the climate is specially harsh, like in the Chill, or organisms need special adaptations to live in that item habitat, similar mangrove trees that tin can tolerate living in saltwater. As humans move effectually the globe, more not-native species are turning up in these harsh habitats, some from like habitats in other parts of the world. These species are more likely to become invasive.
Here are some ways invasive species touch on native ecosystems:
- Habitat modification
- Compete with native species for resources
- Predation of native species
- Herbivory on native plants
- Bring in pathogens
- Hybridize with natives, leading to loss of genetic diversity
European beachgrass (Ammophila arenaria) was introduced to sand dunes on the coast of California, Oregon and Washington in the 1800s. Beachgrass was planted to stabilize the e’er-shifting dunes, and it worked well. Also well. European beachgrass forms huge stands of tall, itchy grass and is usually the only species living on dunes that once had a large diverseness of native grasses and wildflowers. The beachgrass provides more embrace for predators that eat seabirds and native plants.
In another example of habitat modification, N American beavers (Castor canadensis) became invasive in Tierra del Fuego, Argentina. In the 1940s, 50 beavers were introduced to beginning a fur industry. Now, there are betwixt fifty,000 and 100,000 beavers wreaking havoc on the native trees. Unlike many North American trees that abound back from their roots when beavers chew them down, South American copse such equally the southern beech die when a beaver gnaws downwardly their trunk. Beavers have turned twoscore million acres of forest into meadows and converted streams into bogs.
Competition for resources:
Invasive species can compete with natives for food and space. Zebra mussels (Dreissena polymorpha) have spread throughout the Bully Lakes region very quickly since the 1980s. Mussels need difficult surfaces to live on, and zebra mussels take up space that native mussels could use, or sometimes just settle on top of the native mussels, killing them in the procedure.
Zebra mussels (black) took upward residence on this endangered species, the Higgins eye pearly mussel (yellowish). Image from here.
Guam, an island in the Pacific Sea, has lost almost of its birds to an invasive species. The brown tree snake was introduced to the island and wiped out three-quarters of the native bird species and 2 of the eleven native lizard species. Brown tree snakes accept been introduced to other Pacific islands and had like impacts in those places by eating eggs, young and adult birds, and reptiles.
The brown tree snake can climb trees and catch birds.
On the eastern side of the U.s., two insects have been wiping out ascendant copse. The Asian balsam woolly adelgid (Adelges piceae) has killed 90-99% of Fraser fir trees in some areas in the Appalachians by sucking the sap out of the trees. This adelgid as well affects fir trees in Washington state and Oregon. Its relative, the hemlock woolly adelgid (Adelges tsugae), has killed most hemlock trees in New England.
Invasive species can be pathogens. One famous instance is chestnut bane, a mucus that killed off pretty much all the chestnut trees in the eastern US by the 1940s. Chestnut trees, which were dominant throughout much of the eastern US, were replaced by oak copse. The effect of this change in ascendant species was not fully studied at the fourth dimension, only scientists believe that several species of moths went extinct when their chestnut tree hosts disappeared.
Sometimes species’ genetic compositions can change drastically by mating with closely related species, making the less common species extinct past hybridization. Endemic species—those that live just in i place and nowhere else—are particularly vulnerable to hybridization if closely related species are introduced. North American mallards (Anas platyrhynchos) have been introduced in many places around the world and mate with other ducks in those places. Endemic ducks in Florida, Hawaii, New Zealand and Africa are in danger of extinction because of hybridization with the introduced North American mallard.
The Hawaiian duck is threatened by hybridization with the N American mallard. Image from here.
Since invasive species have such a big touch on on biodiversity, many groups attempt to control or eradicate them. Efforts include manual removal, pesticides, and biological controls. Biological controls, or “biocontrols,” work past finding a predator or pathogen from the native range of the invasive species and introducing it where the species has become invasive. Sometimes this is successful just other times it has atrocious unforeseen consequences. Pikestaff toads were introduced to Australia to command the native cane beetle, which was harming sugar cane crops. The toads did non command the cane protrude, and reproduced so quickly that they spread all over Australia. Cane toads produce toxic secretions, which harm native predators and makes eradicating the toads hard.
One method of getting rid of invasive species is to eat them. Hear about ane attempt here.
Introduced Species Can Threaten Biodiversity Because They Can