363 lecture 10-2008 - Population growth 1

363 lecture 10-2008 - Population growth 1 - Megabite one...

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Megabite — one element of Australia's ancient megafauna, the giant goanna ( Megalania prisca ), dines off another, the marsupial Diprotodon opatum .
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“The first rule of intelligent tinkering is to save all the parts” Aldo Leopold – A Sand County Almanac
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Global warming puts frogs at risk of deadly fungal epidemic A FUNGAL epidemic that is wiping out amphibian populations could be driven by global warming. Alan Pounds at the Monteverde Cloud Forest Reserve in Costa Rica and his colleagues have found a strong correlation between the timing of frog extinctions and changes in sea surface and air temperatures in the tropical mountains of Central and South America. Increased cloud cover in the mountains is making for cooler days and warmer nights. These conditions favour the growth of the pathogenic fungus Batrachochytrium dendrobatidis , which thrives between 17 and 25 °C ( Nature , vol 439, p 161). The fungus dehydrates its victims and is believed to have driven 74 out of 110 species of Atelopus harlequin frogs to extinction in recent years. Pounds had suspected that the sudden proliferation of B. dendrobatidis might be linked to climate change, but the exact relationship was unknown ( New Scientist , 8 May 1999, p 32). "Global warming is loading the dice in favour of this disease- causing fungus," he says. Shifts in host-parasite interactions caused by climate change could pose a greater threat to biodiversity than had previously been imagined. Estimates that a quarter of land animals and plants may suffer climate-related extinction by 2050 are now looking conservative, Pound says. From issue 2534 of New Scientist magazine, 14 January 2006, page 18
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aposematic
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Lyme Disease
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Activities of modern humans that threaten biodiversity by causing extinctions 1. Overexploitation (Chapter 10) 2. Introduced species (Chapter 10) Predators (commensalism) Competitors (cattle, carp, plants) Diseases (bird pox, malaria) 3. Domino extinctions ( Calvaria major - Dodo) 4. Habitat destruction (Chapter 9) 5. Global climate change (Chapter 9) 6. Warfare (conventional and nuclear) 20A
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Deforestation 13 million hectares per year (FAO 2005) 1975 estimate was 25 acres (10 hectares) per minute (annually, an area the size of WV (P. and A. Ehrlich) 150,000 km 2 per year, 25 hectares per minute, one football field every second (N. Myers 1989). “If the current rate of deforestation continues, the world's rain forests will vanish within 100 years-causing unknown effects on global climate and eliminating the majority of plant and animal species on the planet.” – NASA 2.4 football fields/hectare 2
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Figure 2. Satellite image of deforestation in the Amazon region, taken from the Brazilian state of Para on July 15, 1986. The dark areas are forest, the white is deforested areas, and the gray is re-growth. The pattern of deforestation spreading along roads is obvious in the lower half of the image. Scattered larger clearings can be seen near the center of the image.
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363 lecture 10-2008 - Population growth 1 - Megabite one...

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