Patterns, Causes, and Consequences of Anthropocene Defaunation

Abstract

The modern process of defaunation can be alarmingly obvious or surprisingly cryptic, depending on the scale examined. It is thus important to distinguish three interrelated spatial scales of defaunation. 3.1.1. Global extinction. At a global scale, human-associated extinction of animal life on the planet is profound. Modern rates of vertebrate extinctions have been estimated to be up to 100 times greater than the most conservative background rates of ∼2 vertebrate extinctions per million species per year (Ceballos et al. 2015). Although most of the extinctions to date have been documented in terrestrial ecosystems (e.g., 338 vertebrates since the year 1500) (IUCN 2015), the highest proportion of extinctions has been recorded in freshwater ecosystems (Collen et al. 2014). Marine ecosystems, by comparison, lag much further behind, with only ∼15 marine animal extinctions recorded during this same time period (McCauley et al. 2015b). Regarding invertebrates, information on global extinctions (or defaunation in general) is very limited (Supplemental Figure 1; follow the Supplemental Material link from the Annual Reviews home page at http://www.annualreviews.org), but recent efforts on the levels of threat to species in the International Union for Conservation of Nature (IUCN) Red List (Collen et al. 2012) provide some insights. Of the 3,623 terrestrial invertebrate species assessed on the Red List, 42% are classified as threatened with extinction. Of the 1,306 species of marine invertebrates on the Red List, close to 25% are threatened with extinction. Finally, of the 7,784 species of freshwater invertebrates on the Red List, 34% are listed as threatened, but the Red List includes 131 species classified as extinct. Invertebrates, however, are the least well evaluated faunal groups within the IUCN database, making it challenging to determine precisely the risks faced by data-deficient and unreviewed species (Dirzo et al. 2014, McCauley et al. 2015b).

Biological annihilation via the ongoing sixth mass extinction signaled by vertebrate population losses and declines

“…Hundreds of species and myriad populations are being driven to extinction every year (1)(2)(3)(4)(5)(6)(7)(8). From the perspective of geological time, Earth's richest biota ever is already well into a sixth mass extinction episode (9)(10)(11)(12)(13)(14).…”

Amazônia no Antropoceno: o manejo como relação entre humanos e fauna silvestre

“…Estudos mostram que esse processo já tenha ocorrido outras cinco vezes, e a atual seria a sexta grande ex nção no planeta (KOLBERT, 2015;YOUNG et al, 2016;CEBALLOS;EHRLICH;DIRZO, 2017). A defaunação é resultado das Amazônia no Antropoceno: o manejo como relação entre humanos e fauna silvestre ações dos humanos em escalas globais e locais, como mudanças climá cas, poluição oceânica, a caça direta, doenças endêmicas, espécies invasoras a supressão e modifi cação de habitats pelo desmatamento (DIRZO et al, 2014;YOUNG et al, 2016).…”

“…As consequências da defaunação impactam as estruturas ecológicas e as funções/serviços ecossistêmicos, tais como os padrões evolu vos das espécies, a abundância, a ecologia dos biomas, a polinização, no controle biológico, alteração no ciclo dos nutrientes bem como na qualidade da água (DIRZO et al, 2014;YOUNG et al, 2016). Para Ceballos, Ehrlich e Dirzo (2017), a humanidade está atrasada para planejar uma ação efe va, pois o período é curto, provavelmente duas ou três décadas no máximo.…”

“…Mas, de acordo com análises de Dirzo et al (2014) e Young et al (2016), por estarem em ecossistemas tropicais de água-doce, o risco aumenta, pois o número de animais em ex nção é nove vezes maior nesses locais, quando comparado ao dos animais em ecossistemas marinhos.…”

Loss of Seed-Dispersing Animals and Its Impacts on Humanity

“…The global loss of species of the fauna or the reduction of individuals within the populations, caused directly or indirectly by human influence, is known as defaunation, and is currently the subject of several researches due to the disastrous consequences driven by a possible and accelerated sixth mass extinction of animals on the planet (Young et al 2016). It is estimated that since the beginning of the first navigations, 322 species of terrestrial vertebrates have been extinct, especially those of medium and large size, and that of the remaining populations, one in four has can have systemwide consequences in a variety of ways.…”