E10. Human practices can lead to major changes in communities.

E10.1 Give examples of species’ extinctions that have been brought about by human activities.

EXTINCTAnimals presumed to be

in the past decade...

EXTINCT (EX)“A taxon is Extinct when there is no reasonable doubt that the last individual has died. A taxon is presumed Extinct when exhaustive surveys in known and/or expected habitat, at appropriate times (diurnal, seasonal, annual), throughout its historic range have failed to record an individual. Surveys should be over a time frame appropriate to the taxon’s life cycle and life form.” (IUCN 2012, p.14)

Golden toadIncilius periglenes

A species that lived only in the Monteverde Cloud Forest Biological Reserve in Costa Rica.

The amphibian disease chytridiomycosis, airborne pollution and global warming probably contributed to the species' demise.

Baiji dolphinLipotes vexillifer

The last documented sighting of China's baiji dolphin, or Yantze River dolphin, was in 2002, and while the species is listed as critically endangered, scientists say it may already be extinct.

The decline in the baiji dolphin population is attributed to a variety of factors including:•overfishing•boat traffic•habitat loss•pollution •poaching.Called "the goddess of the river“, the dolphin's skin was highly valuable and used to make gloves and handbags.

Pyrenean ibexCapra pyrenaica

The Pyrenean ibex is one of two extinct subspecies of the Spanish ibex. The species was once numerous and roamed across France and Spain.

Last Pyrenian ibex called Celia as killed by a falling tree on January 6 2000.

Skin cells from ear preserved.Scientists made the Pyrenean ibex unextinct in 2009.

Some hypotheses as to why the Pyrenean ibex became extinct include poaching, diseases and the inability to compete with other species for food.

Western black rhinocerosDiceros bicornis ssp. longipes

Extensive survey of Cameroon in 2006 showed no sign of rhinoceros.

No sightings since 2006.

The extinction of this subspecies of black rhinoceros has been caused by:•wildlife poaching•lack of political will and conservation effort•illegal demand of rhinoceros horn

The dodoRaphus cucullatus

EndemicDefined to a specific geographic location.

Characteristics

• Forest-dwelling• Flightless: only had winglets• Large, plump bird covered in soft, grey

feathers• 13-23kg in size• No defenses except its beak

Extinction

• Portuguese sailors led by Captain Mascaregnas in 1507

• Blown off course from travelling to Cape of Good Hope in South Africa.

• Other expeditions by Portuguese, Dutch, British and others.

• Sailors ate dodos if desperate.

Extinction - continued

• Dutch colonised the area in 1644.• Cats, dogs, swine and monkeys brought.– Invaded woods– Trampled nests– Frightened birds– Devoured eggs and young

• Extinct by 1681.

(Brown 2002)

The ThylacineThylacinus cynocephalus

Originally across mainland Australia, New Guinea and Tasmania

Characteristics

• AKA Tasmanian Wolf or Tasmanian Tiger• Sandy-yellow/brown to grey• 15-20 dark stripes across the back• Dog-like head• Stiff tail• Short legs• Nocturnal

Extinction

• Wiped from the Australian mainland approximately 2000 years ago.– competition with dingo– hunting pressure from humans (food)

• Alleged pest– sheep and poultry

(McKnight 2008)

E10.2 Explain why the best way to preserve species is to

preserve habitat.

Key terms

• Endemic species• Habitat fragmentation• Species diversity

ReferencesBrown, B 2002, Raphus cucullatus, accessed 24

September 2013, <http://animaldiversity.ummz.umich.edu/accounts/Raphus_cucullatus/>

IUCN, 2012, IUCN Red list categories and criteria, IUCN, Gland, Switzerland.

McKnight M 2008, Thylacinus cunocephalus, accessed 24 September 2013, < http://www.iucnredlist.org/details/21866/0>