environmental biology presentation wildlife extinction robert i. walls spring 2012 professor donald...
TRANSCRIPT
Environmental Biology Presentation
Wildlife Extinction
Robert I. Walls
Spring 2012
Professor
Donald Keith
History
The Irish Elk
• First documented extinction– Discovered by Thomas
Molyneux, 1697
– Extinction described by Georges Cuvier, 1812
Museum of Natural History, Washington D.C.
The Five Extinction Events
• Ordovician–Silurian• Late Devonian
• Permian–Triassic• Triassic–Jurassic• Cretaceous–Tertiary
Palais de la Découverte, Paris, photo by David Monniaux.
The Sixth Extinction Event
The Two Phases
• Human dispersal ~100,000 B.P.
• Agriculture discovered ~10,000 B.P.
The Most Susceptible
• K-selected
• Specific survival requirements
• Small population size
• Close to humans
• No conservation programs
Major Causes
• Overexploitation
• Pollution
• Invasive exotics
• Habitat Degradation
Overexploitation
Dodo Birds
• Island of Mauritius• Used as food by
Portuguese sailors• Exotic species
introduced• Extinct by 1681• Tree found to depend
on Dodo digestion of seeds for germination
Saddle-backed RodriguesGiant Tortoise
• Island of Rodrigues, Republic of Mauritius
• Hunting pressure• Last reported: 1795
In 1761, Abbé Pingré wrote: "The tortoise is not a pretty animal, but it was the most useful of those we found at Rodrigues. In the three and a half months that I spent on the island, we ate almost nothing else: tortoise soup, fried tortoise, stewed tortoise, tortoise forcemeat, tortoise eggs, tortoise liver - these were pretty much our only savouries. This meat seemed to me as good on the last day as on the first; I did not eat many of the eggs; the liver seemed to me the most delicious part of the animal. After five weeks stay I was attacked by dysentery which I kept secret, because I counted more on myself to heal it than the island's surgeon. Diet and rest put me right in a few days, but it left me with an extraordinary involuntary repugnance for this liver that I had so liked until then. Should I thus regard it as the cause of my indisposition?...Tortoise fat is very abundant and does not congeal; it is what is known as tortoise oil. This oil had no bad taste, it is very healthy, and we seasoned our salads with it, used it in frying and all our sauces. Rodrigues tortoises are a foot and a half long and bout a foot across; they were formerly large, but they are no longer given time to grow. When a bigger one is found, it is called a carrosse. These carrosses cannot harm a waken man, though they have sometimes bitten sleepers hard. The shells of these tortoises served us like baskets to carry oysters and similar provisions. The flesh of these tortoises is the colour of mutton, and approaches it for taste" (Pingré, 1763; Cheke and Hume, 2008).
Quagga
• South Africa• Aggressively Hunted• Used for meat• Skin used for grain
bags and leather
The only living quagga ever photographed - at the London Zoo in 1870, 13 years before the subspecies went extinct
Sperm Whale Harvest Records for the United States
Year # Ships Est. Whales Est. Oil Barrels1835 500 7,598 172,6831840 559 6,943 157,7911845 696 6,494 157,9171850 543 4,088 92,8921855 638 3,197 72,6491860 569 3,243 73,7081865 276 1,463 33,2421870 321 2,428 55,18318751880 173 1,656 37,6141885 133 1,065 24,203
Data from Gosho et al. 1984
Pollution
Bird Sanctuary
• DDT effects on birds first studied by Rachel Carson (late 50’s to early 60’s)
• Deaths of robins, catbirds, doves, jays, wrens, and other birds linked to pesticide exposure
Invasive Exotics
The Tasmanian “Wolf”
• Canine-like marsupial• Competed with
introduced dingo• Bounty placed by
Europeans
Habitat Degradation
Three Tiger Subspecies
• Bali• Javan• Caspian
Guam Flying Fox
• Guam, Marianas Islands, Micronesia
• Last record: 1974• Habitat degradation
and hunting believed to be causes of extinction
Gastric Brooding Frog
• Eastern Australia• Offspring incubated in
stomach• Last seen in 1985
IUCN Red List of threatened species
• 10,002 vulnerable
• 5,689 endangered
• 3,879 critically endangered
• 64 extinct in wild
• 801 extinct
Literature CitedCarson, R. 1962. Silent Spring. Houghton Mifflin. Boston, MA.
Gould, S. J. 1974. The Origin and Function of 'Bizarre' Structures: Antler Size and Skull
Size in the 'Irish Elk,' Megaloceros giganteus. Evolution 28(2):191-220.
Lowenstein, J. M. and O. A. Ryder. 1985. Immunological systematics of the extinct Quagga
(Equidae). Experimentia 41:1192-1193.
Vernon, J. E. N. 2008. Mass extinctions and ocean acidification: biological constraints on
geological dilemmas. Coral Reefs 27(3):459-472.
Gosho, M. E., D. W. Rice, and J. M. Breiwick. 1984. The sperm whale, Physeter macrocephalus. Marine Fisheries Review 46(4):54-56.
Bringing Back the Quagga. 2006. http://www.southafrica.info/about/animals/quagga.htm.
Accessed 02/23/2012.
Cylindraspis vosmaeri. 2009. http://www.petermaas.nl/extinct/speciesinfo/rodriguestortoise.
htm. Accessed 03/16/2012.
Gastric Brooding Frog. 2012 http://www.conservation.org/learn/biodiversity/species/
profiles/amphibians/Pages/Rheobatrachus_vitellinus-silus.aspx. Accessed 03/17/2012.
Guam Flying Fox - Pteropus tokudae. 2011. http://www.petermaas.nl/extinct/speciesinfo/
guamflyingfox.htm. Accessed 03/16/2012.
The Dodo Bird Extinct. http://www.bagheera.com/inthewild/ext_dodobird.htm. Accessed
03/20/2012.