Question | Answer |
MASS DISTINCTION | The extinction of many species in a relatively short period of time is called a ______ ________. |
SEVERAL | Earth has experienced ______ mass extinctions, each probably caused by a global change in climate. |
MILLIONS | It takes _______ of years for biodiversity to rebound after a mass extinction. |
WARNING | Scientists are _______ that we are in the midst of another mass extinction. |
25 % | The rate of extinctions is estimated to have increased by a multiple of 50 since 1800, with up to __ percent of all species on Earth becoming extinct between 1800 and 2100. |
HUMANS | The current mass extinction is different from those of the past because _________ are the primary cause of the extinctions. |
LARGE | ____ populations that adapt easily to many habitats are not likely to become extinct. |
SMALL | However, ____ populations in limited areas can easily become extinct. |
RISK | Species that are especially at ___ of extinction are those that migrate, those that need large or special habitats, and those that are exploited by humans. |
THREATENED SPECIES | A _______ ______ is a species that has been identified to be likely to become endangered in the foreseeable future. |
2 | In the past _ centuries, human population growth has accelerated and so has the rate of extinctions. |
SPECIES | The number of worldwide _____ know to be threatened, endangered, or recently extinct are listed on the next slide. |
LAND | As human population grow, we use more ____ to build homes and harvest resources. |
DESTROY | In the process, we ______ and fragment the habitats of other species. |
75% | It is estimated that habitat loss causes almost __ percent of the extinctions now occurring. |
FLORIDA PANTHER | For example, cougars, including the _____ ____ require expansive ranges of forests and large amount of prey. |
HABITAT | Today, much of the cougars' ________ has been destroyed or broken up by roads, canals , and fences. |
150 | In 2011, only about ___ Florida panthers made up the only remaining wild cougar population east of the Mississippi River. |
EXOTIC SPECIES | An _______ ______ is a species that is not native to a particular region. |
NO | Exotic species can threaten native species that have __ natural defenses against them. |
POACHING | _________ is the legal harvesting to fish, game, or other species. |
PESTICIDES | ___________, cleaning agents, drugs, and other chemicals used by humans are making their way into food webs around the globe. |
YEARS | The long term effects of chemicals may not be clear until after many ______. |
ENDEMIC SPECIES | An _______ ________ is a species that is native to a particular place and that is found only there. |
PLANTS | Ecologists often use the numbers of endemic species of ________ as an indicator of overall biodiversity because plants from the basis of ecosystems on land. |
UNKNOWN | Most of the species have never been described. ___________ numbers of these species are diss |
TROPICAL | _________ forests are also among the few places where some native people maintain traditional lifestyles. |
REEFS | _____ provide millions of people with food, tourism revenue, costal protection and sources of new chemicals, but are poorly studied and not as well protected by laws as terrestrial areas are. |
60% | Nearly __ _______ of Earth's coral reefs are threateatened by human activities, such as pollution, development along waaterways, and overfishing. |
COASTAL | Similar threats affect _______ ecosystems, such as swamps, marshes, shores, and kelp beds. |
DISTINCT | Thus, islands often hold a very ________ but limited set of species. |
70% | Most of these hotspots have lost at least __ % of their original natural vegetation. |
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