Licenciado

In biology and ecology, extinction is the disappearance of all members of a species or group of taxa. It is considered a species extinct from the moment that the lastindividual dies of this. Because its range potential can be very large, determining the time can be difficult, so it is usually done in retrospect. These difficulties can lead tophenomena such as Lazarus taxa, where a species presumed extinct abruptly reappears after a period of apparent absence. In the case of sexually reproducing species, extinctionis usually inevitable when only one individual of the species, or only individuals of the same sex.

Through evolution, new species arise through speciation, as well asother species become extinct when they are no longer able to survive in changing conditions or against other competitors. Normally, a species becomes extinct within the first10 million years after its first appearance, 2 although some species, called living fossils, survive virtually unchanged for hundreds of millions of years. Extinction isusually historical and natural phenomena. It is estimated that about 99.9% of all species that ever existed are now extintas.3 4

Before the spread of humans across the planet,extinction generally occurred in continuous low rate, and mass extinctions were relatively rare events. But about 100,000 years ago, and coincided with the increase inpopulation and the geographical distribution of humans, extinctions have increased to levels not seen since before the Cretaceous mass extinction-Terciario.5 This is known as theHolocene mass extinction, and it is estimated that by 2100 the number of extinct species could reach high levels, even half of all the species that exist actualmente.6 July 8