Invasive species - Definition, examples and consequences

Author: Laura McKinney
Date Of Creation: 2 August 2021
Update Date: 20 September 2024
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The threat of invasive species - Jennifer Klos
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The introduction of species into ecosystems where they are not naturally found can have very serious consequences for biodiversity. These species can settle down, reproduce and colonize new places, replacing the native flora or fauna and altering the functioning of the ecosystem.

Invasive species are currently the second largest cause of biodiversity loss in the world, second only to habitat loss. Although these species introductions have taken place since the first human migrations, they have greatly increased in recent decades due to global trade. If you want to know more, don't miss this PeritoAnimal article about invasive species: definition, examples and consequences.


Definition of invasive species

According to the International Union for Conservation of Nature (IUCN), an “invasive alien species” is an alien species that establishes itself in a natural or semi-natural ecosystem or habitat, becoming an change agent and a threat to native biological diversity.

Therefore, invasive species are those able to successfully reproduce and form self-sufficient populations in an ecosystem that is not yours. When this happens, we say that they have "naturalized", which can have disastrous consequences for native (native) species.

Some invasive alien species they are unable to survive and reproduce on their own, and thus end up disappearing from the ecosystem and not endangering native biodiversity. In this case, they are not considered invasive species, just introduced.


Origin of invasive species

Throughout their existence, human beings made great migrations and took with them species that helped them survive. Transoceanic navigations and explorations have greatly increased the number of invasive species. However, the globalization of trade that has taken place over the last century has exponentially increased the introduction of species. Currently, the introduction of invasive species has various origins:

  • Accidental: animals "hidden" in boats, ballast water or car.
  • Pets: It is very common for people who buy pets to get tired of them or cannot take care of them, and then decide to release them. Sometimes they do this thinking they are doing a good deed, but they don't take into account that they endanger the lives of many other animals.
  • aquariums: the discharge of water from aquariums where there are exotic plants or small animal larvae has led to the invasion of rivers and seas by many species.
  • Hunting and fishing: both the rivers and the mountains are full of invading animals due to the release by hunters, fishermen and, sometimes, by the administration itself. The objective is to capture flashy animals as trophies or food resources.
  • gardens: ornamental plants, which are very dangerous invasive species, are cultivated in public and private gardens. Some of these species even replaced native forests.
  • Agriculture: Plants that are grown for food, with few exceptions, are generally not invasive plants. However, during their transport, arthropods and seeds of plants that colonized the world, such as many adventitious grasses (“weeds”), can be carried.

Consequences of the introduction of invasive species

The consequences of the introduction of invasive species are not immediate, but they are observed. when a long time has passed since its introduction. Some of these consequences are:


  • Species extinction: Invasive species can end the existence of the animals and plants they consume, since these are not adapted to predation or the voracity of the new predator. Furthermore, they compete for resources (food, space) with native species, replacing them and causing their disappearance.
  • Changing the ecosystem: as a consequence of their activity, they can alter the food chain, natural processes and the functioning of habitats and ecosystems.
  • Disease transmission: exotic species carry pathogens and parasites from their places of origin. Native species have never lived with these diseases, and for this reason they often suffer a high mortality rate.
  • Hybridization: some introduced species can reproduce with other native varieties or breeds. As a result, the indigenous variety may disappear, reducing biodiversity.
  • economic consequences: many invasive species become crop pests, decimating crops. Others adapt to living in human infrastructure such as plumbing, causing huge economic losses.

Examples of Invasive Species

There are already thousands of invasive species around the world. In this article by PeritoAnimal, we also bring some examples of the most harmful invasive species.

Nile Perch (Nilotic lates)

These huge freshwater fish were introduced into Lake Victoria (Africa). Soon, caused the extinction of more than 200 endemic fish species due to their predation and competition. It is also believed that the activities derived from its fishing and consumption are related to the eutrophication of the lake and the invasion by the water hyacinth plant (Eichhornia crassipes).

Wolf Snail (Euglandin rose)

It was introduced in some Pacific and Indian islands as predator from another invasive species: the giant african snail (Achatina sooty). It was introduced as a food and pet resource in many countries until it became an agricultural pest. As might be expected, the wolf snail not only consumed the giant snail but also exterminated many native species of gastropods.

Caulerpa (Taxifolia caulerpa)

The caulerp is probably the most harmful invasive plant in the world. It is a tropical alga that was introduced to the Mediterranean in the 1980s, probably as a result of water being dumped from an aquarium. Today, it is already found throughout the Western Mediterranean, where it is a threat to native patterns in which many animals breed.

Invasive species in Brazil

There are several invasive alien species that were introduced in Brazil and that can cause social and environmental damage. some of invasive species in Brazil are:

mesquite

Mesquite is a tree native to Peru that was introduced in Brazil as a forage for goats. It causes the animals to wear out and invade pastures, causing them to die earlier than supposed.

Aedes Aegypti

An invasive species well known for being a transmitter of dengue. The mosquito originates from Ethiopia and Egypt, tropical and subtropical regions. Although it is a vector of disease, not all mosquitoes are contaminated and pose a danger.

Nile Tilapia

Also native to Egypt, the Nile tilapia arrived in Brazil in the 20th century. This invasive species is omnivorous and reproduces very easily, which ends up contributing to the extermination of native species.

If you want to read more articles similar to Invasive species - Definition, examples and consequences, we recommend that you enter our Curiosities section of the animal world.