Sea turtles are listed on the IUCN Red List as 'endangered', 'vulnerable' or 'critically endangered'. The extinction of a species corresponds to the total disappearance of the representatives of an animal or plant species or when the latter no longer has the possibility of reproducing. Due to pollution, the destruction of habitats, overexploitation or global warming, the number of species is disappearing every day.
When do we speak of extinction?
When the removals or the disappearance of individuals of the same species reach a critical size, the population drops and can take several decades before growing again.
This problem is even more serious when it affects endemic species, that is to say species which only exist in a given region of the globe. For example the Galapagos tortoises, or the green lizard, pug anole, Martinique anoli is endemic but remains common. On the other hand, tarantula Avicularia versicolor (locally called "matoutou cliff"), which reputed to be one of the most beautiful in the world, is threatened: its range is very restricted and it is the victim of poaching. A prefectural decree fully protects this tarantula as well as the Dynaste de Martinique, Dynastes hercules baudrii , also endemic to Martinique.
The risk for these species is to disappear completely, therefore to become extinct.
The causes of extinction
Through evolution, new species appear through the process of speciation. At the same time, others disappear when they are no longer able to survive in changing conditions or in the face of competition that they cannot face. Natural selection propagates beneficial genetic traits and eliminates weaknesses.
To the old causes of extinction (ecological crises, natural disasters) and natural (predation, competition, diseases) are added anthropogenic causes, in other words linked to man, such as pollution, overexploitation of natural resources, destruction of habitats …as well as the effects of climate change.
The extinction of a wild population of a species can lead to additional extinctions, known as "chain extinctions" or co-extinctions, for example when a plant species loses its main pollinator species, or when a predator has no more prey.
Similarly, a species can disappear because of the arrival of a new species which will eliminate it by predation or competition. This new species is said to be invasive. The green iguana Iguana iguana , introduced in Martinique, competes with or even dominates the endemic iguana, the Lesser Antillean iguana , Iguana delicatissima . It could drive it to extinction if we do not control its expansion. lionfish (Pterois volitans Where Pterois miles) , also called dragon fish or lionfish, which arrived in the waters of the French West Indies in 2011 is considered an invasive marine species, in addition to being venomous.
Martinique's Amazon (Amazona martinicana) was an endemic parrot of Martinique, now extinct. The cause of this extinction is the destruction of its habitat by man. It is therefore classified in the IUCN as "extinct (EX) in the IUCN Red List ”. The same is true for the emblem of the municipality of Lamentin, the manatee Trichechus manatus , whose reintroduction has been discussed.
the dodo (Raphus cucullatus) , flightless bird of Mauritius, vulnerable due to its inability to fly, has completely disappeared after the introduction of rats on the island, in addition to having been massacred by dogs, pigs, cats … and men.
Among the species famous for their extinction, we have the dinosaurs, just like the mammoth, or the extinct human and pre-human species such as the australopithecines, Homo habilis, Homo erectus, Homo neanderthalensis …
Species at high risk of extinction, according to the WWF (World Wildlife Fund) :
- The great white shark , Carcharodon carcharias: his only predator is man. The capture of this shark has become a real feat since the release of the Sea teeth by Steven Spielberg in 1975.
- bengal tiger , Panthera tigris tigris, as well as Sumatran and Siberian tigers: they are hunted for their fur and their organs, reputed to have miraculous medical properties, as well as the destruction of their habitat. The majestic white tiger would have already disappeared in the wild and would only survive in captivity, in zoos and parks.
- Asian elephant , Elephas Maximus : deforestation, poaching especially for ivory trafficking and its capture for zoos are decimating the wild populations of this already rare pachyderm.
- mountain gorilla , Gorilla gorilla beringei , the largest of the primates, has seen deforestation and poaching reduce its numbers considerably.
- giant panda , Ailuropoda melanoleuca , which has become the emblem of endangered animals: there are less than 2000 left in the forests of Tibet and China due to deforestation, the exploitation of bamboo, which constitutes its food, and poaching for its fur. Declared a national treasure by the Chinese government in 1949, it was chosen in 1961, as the rarest animal in the world, as an emblem by the WWF .