Invasive species: what are they, examples and consequences

We start by clarifying what exactly is an invasive species. When we speak of invasive species, we refer to species of remote origin that, upon reaching a new place, establish themselves and spread at great speed, modifying the structure and functioning of the ecosystem.

As a common factor, all invasive species have characteristics that explain the success of invasions: high growth and reproduction rates. Furthermore, biological invasions can be favored by the similarity of the climatic conditions with those of the region of origin of the species and, also, by the degree of vulnerability or susceptibility of the native biota.

The biological invasion process consists of three stages:

1. Transport stage , where a species is transported from its place of origin to a new territory. From that moment the species is classified as exotic. However, how invasive species get to new territories is a complex issue, although most species are deliberately transferred, some specimens are accidentally transported, as in the case of weeds whose seeds can be harvested with commercial seeds or even rats. and insects that live aboard ships and airplanes.
2. Settlement stage , occurs when the exotic species finds favorable conditions to survive and reproduce in the new ecosystem, so that it can form populations. In this instance the species has become naturalized.
3. Propagation stage , happens when the naturalized species has a higher propagation capacity than that of the ecosystem’s own species, a fact that leads to the alteration of the environment. Now the species is considered invasive.

In this section, we present some examples of invasive species in Spain, Argentina and Mexico and we develop two cases of invasive species and their impacts .

Examples of invasive species in Spain

• American mink ( Neovison vison )
• Argentine parrot ( Mylopsitta monachus )
• American crab ( Procambarus clarkii )
• Camalote (Eichhornia crassipes)
• Alianto ( Ailanthus altissima )

If you want to know more examples of invasive species in this country, we recommend that you read our article on invasive species in Spain and their consequences .

Examples of invasive species in Argentina

• Red-bellied squirrel ( Callosciurus erythraeus )
• Red deer ( Cervus elaphus )
• Beaver ( Beaver )
• Black Acacia ( Gleditsia triacanthos )
• Paper mulberry ( Broussonetia papyrifera )

Examples of invasive species in Mexico

• Feral pig or wild boar ( Sus scrofa )
• Rata negra (Rattus rattus)
• Zebra mussel ( Dreissena polymorpha ). It has also invaded the Spanish coasts.
• Red lionfish ( Pterois volitans ). Originally from the Indian Ocean, it has invaded the waters of Mexico and also the Spanish marine waters in the Mediterranean Sea.
• Mother of thousands ( Kalanchoe delagoensis )
• Water lily ( Eichhornia crassipes )

The case of the Argentine parrots in Spain

Possibly you have ever heard the problem of Argentine parrots in Madrid, one of the best known cases of invasive animals. This species was introduced by man in the 1980s, for its attractiveness as a pet. However, as a result of escapes or intentional releases, the Argentine parrot managed to establish not only in Madrid but also in other parts of the country (for example, they are very abundant in Barcelona), reaching a population of approximately 20,000 specimens throughout Spain. The establishment of this invasive species causes problems of various kinds, including: ecological problems, such as the displacement of native species; social problems, such as noise pollution in urban areas, transmission of diseases to humans and the possible fall of their nests that, due to their weight, can be lethal; and also economic problems as they cause significant damage to crops.

The case of the black acacia in Argentina

An exemplary case of invasive plantsIt is the black acacia native to the United States, which was introduced in the pampas grasslands of Argentina from 1800 during the European colonization. Today, black acacia specimens have spread throughout the country. In particular, they have been installed on the coasts of rivers and streams, considerably modifying the ecosystem. On the one hand, its presence reduces the availability of light, which primarily harms photosynthesizing organisms and, consequently, the entire food chain. Likewise, the presence of the black acacia represents a difficulty for the fauna, since it has many branches with large thorns. In this way, the native species are displaced because due to the alteration of their habitat they do not present a safe place of refuge, feeding and nesting.

Here you can learn more about what are invasive plants and examples of species .

As we have indicated at the beginning, the great consequence of biological invasions is the loss of biological diversity . In this other article you can learn more about the causes and consequences of biodiversity loss .

You are probably wondering what damage invasive species do to biodiversity. The establishment of invasive species causes, in the first place, the displacement of native species , mainly when the invasive species uses the resources of the native species but with greater efficiency. They also cause alterations in the interaction networks between species, since it is frequent, for example, that invasive plant species compete with native ones for pollinators and dispersers in the ecosystem. Furthermore, we cannot ignore the possibility that invaders bring with them diseases or pests to which they are resistant, but not local biodiversity.

You can learn more about what is a native or autochthonous species with this other AgroCorrn article.

The possible solutions to the problem of invasive species are not easy to find, because once the species has established itself , it is difficult to eradicate. Despite this, there are some management strategies :

• In principle, the ecosystems are constantly monitored to achieve early detection.
• Then the control of invasive populations, that is, reduce the abundance of the species and limit its distribution.
• Lastly, mitigation is done. That is, using strategies that do not target the management of the invasive species, but rather the resource that is to be conserved.

However, the best strategy is prevention, since avoiding the introduction of exotic species , which can later become invasive, is less expensive than other management strategies. In this other post we talk more about the introduction of exotic species: causes and consequences .

If you want to read more articles similar to Invasive species: what they are, examples and consequences , we recommend that you enter our Biology category .