![]() ![]() In this case, the diversity of species on the planet remains more or less stable.īut when entire ‘branches’ (genera) fall off, it leaves a huge hole in the canopy - a loss of biodiversity that can take tens of millions of years to regrow through the evolutionary process of speciation. Pictured in terms of the tree of life, if a single ‘twig’ (a species) falls off, nearby twigs can branch out relatively quickly, filling the gap much as the original twig would have. “We would be unethical not to explain the magnitude of the problem, since we and other scientists are alarmed.” “As scientists, we have to be careful not to be alarmists, but the gravity of the findings in this case called for more powerful language than usual,” Dr. ![]() Seventy-three genera of land-dwelling vertebrates, the authors found, have gone extinct since 1500 CE.īirds suffered the heaviest losses with 44 genus extinctions, followed in order by mammals, amphibians, and reptiles. Gerardo Ceballos from the Universidad Nacional Autonoma de Mexico and Stanford University’s Professor Paul Ehrlich to assess extinction at the genus level.ĭrawing from those sources, the researchers examined 5,400 genera of land-dwelling vertebrate animals, encompassing 34,600 species. Information on species’ conservation statuses from the IUCN, Birdlife International, and other databases has improved in recent years, which allowed Dr. The precise number of recent extinctions is impossible to know, but current animal species extinction rates are estimated to be hundreds or thousands of times higher than the background rates that prevailed for millions of years prior to the agricultural revolution. In well-studied major taxonomic groups, thousands of species and myriad populations have vanished. Most natural ecosystems have been highly modified or have disappeared altogether, and the abundance of wildlife has been greatly reduced. Over the last century the pace of many human activities has so accelerated, and human overpopulation grown so severe, to have created a dramatic global environmental transformation. Upper row right – ‘i’iwi or scarlet honeycreeper ( Drepanis, left) from Hawaii and kakapo ( Strigops, right) a flightless parrot from New Zealand. (IV) Upper row left: volcano rabbit ( Romerolagus, left) known from few mountains close to Mexico City, and elephant ( Loxodonta, right) from Africa. ![]() Third bottom-up row right – Alpine newt ( Ichthyosaura, left) from Europe and Mahogany frog ( Abavorana, right) from the Malay Peninsula. Endangered genera: (III) Third bottom-up row left – King cobra ( Ophiophagus, left) from Asia and gavial ( Gavialis, right) from India and Nepal. Second bottom-up row right – elephant birds ( Aepyornis, left), the largest birds surviving to modern times, represent also both an extinct genus and family (Aepyornithidae) endemic to Madagascar and Moho birds (genus Moho, right) represent also both an extinct genus and family (Mohidae) from Hawaii. (II) Second bottom-up row left – thylacine ( Thylacinus, left), the largest carnivorous marsupial, last known from Tasmania and Yangtze River dolphin or baijii ( Lipotes, right) from China, one of very few freshwater dolphins. ![]() Lower row right – Yunnan Lake newt ( Cynops, left) from China and the gastric brooding frogs ( Rheobatrachus, right) from rainforests in Queensland, Australia. Extinct genera: (I) lower row left – Delcourt’s giant gecko ( Hoplodactylus, left), of which the only specimens known were found in a museum without a label, but probably they were found in New Zealand and saddle-backed Rodrigues giant tortoise ( Cylindraspis, right) from Rodrigues Island in the Indian Ocean. The bottom half of the tree depicted as dead branches shows examples of the extinct genera, and the upper half shows examples of genera at risk of extinction. Simple schematic representation of the mutilation of the Tree of life because of generic extinctions and extinction risks. ![]()
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