Will future extinctions occur at the same places where the past ones did? A review involving mammals and the IUCN Red List

Abstract

Eighty-five mammal species are classified worldwide as Extinct on the IUCN Red List. In this study, we aimed to assess to which Orders these species belong, when they became extinct and the factors that led to their extinction. We also compared the factors that threatened the survival of these species with the ones that are currently threatening the species classified as Critically Endangered, as well as the areas where the extinct species could be originally found with the areas where Critically Endangered species are currently found. Our review was conducted using the advanced search tool of the IUCN Red List database (Taxonomy, Red List Category, Threats and Land Regions filters). Rodentia was the mammal Order with the highest number of Extinct species, whereas Primates was the Order with the greatest proportion of Critically Endangered ones. The last two (19th and 20th) centuries were the periods in which the greatest number of species was lost. We found remarkable differences between the factors threatening species survival and between countries with the highest number of Extinct species and the ones that contain a greater number of Critically Endangered species. The threat category responsible for most of the extinctions overall was «Invasive and other problematic species, genes and diseases». Nonetheless, factors associated with habitat loss and degradation seem to have become more important nowadays and, in addition, some «new» factors, such as «Energy production and mining», «Human intrusions and disturbance», «Pollution», and «Transportation and service corridors», which have not had much relevance for past extinctions, now appear as important threats to Critically Endangered species. Australia was the country that has lost the most mammal species (n = 26), followed by Haiti (n = 9), the Dominican Republic (n = 8), and Cuba (n = 6). On the other hand, when we evaluated the amount of species classified as Critically Endangered, Madagascar (n = 33), Mexico (n = 27), and Indonesia (n = 26) are the countries that concentrate the highest number of them. Thus, future extinctions are unlikely to occur in the same places as in the past because the human society's relationship with the environment has changed over time: human population has grown, habitat loss has become the predominant threat to many species and new threat factors have emerged.