Goals: Be able to. Basic conflict: Economic opportunity vs. Environmental quality. Human population is growing exponentially

Transcription

1 Goals: Be able to Describe the general history of biodiversity and extinctions on Earth. Discuss why species go extinct. Explain why predators generally need larger land area than herbivores. Describe the perils of roads and habitat fragmentation. Explain how invasive exotic species harm native species. Explain why global warming is more dangerous to survival today than in the past. Basic conflict: Economic opportunity vs. Environmental quality Human population is growing exponentially World species estimates: million, 1.75 million described Risk of Extinction 11% of plants 12% of birds 24% of all mammals 2 2 = = = = = = = = = = = 4, = 8, = 16, = 32, = 65,536 Fig 13.2 Number of species going extinct Birds Mammals Fig

2 The earth s biodiversity has overall increased. Over 99% of the species that have ever lived are extinct Fish/ Dinos Mollusks Trilobites # of Families Due to GCC, extreme vulcanism 96% of species Fig 14.2 Biodiversity: The variety of life Genetic: Different alleles Species Ecosystems: Wetlands, Prairie Causes of extinction 1. Habitat loss and degradation Habitat destruction is #1 cause of extinction Species-area curves Habitat fragmentation More resources More diverse resources Adding species with large ranges Fig

3 Habitat Fragmentation Small areas Food chain: Who eats who Trophic level: One link in a food chain Secondary consumer: Predator Primary consumer: Herbivore Producer: Plant Fig % rule: Only 10% of energy is transferred between trophic levels Wolf needs more area to sustain itself than deer A patch of grass contains 1,000 calories. A deer eats all of the grass, and then a wolf eats the deer. How many calories will the wolf get? calories cal 3. 1,000 cal 4. 10,000 cal Fig 14.8 Habitat Fragmentation Small areas Predators from the edge (cats) Cannot disperse Roads also increase: Pollution Invasive species Habitat destruction Global warming Roads decrease habitat size 3

4 2. Invasive exotic species Why are large carnivores a canary in the coalmine for ecosystems? movie: Extinction tiger Sea lamprey and lake trout Invasive species also compete with native species Purple loosestrife Why do invasive species cause problems? Native populations did not coevolve with them. movie: invasives 3. Overexploitation 4

5 4. Pollution 5. Global warming Migration is hampered by fragmentation Goals: Be able to Provide examples of economic reasons why we should care about biodiversity. Describe ecological communities, and provide examples of the various types of interactions. Discuss the role of a keystone species. Biodiversity why care? Fig 14.9 a) Beneficial wild genetic diversity for crops Disease resistance Biodiversity why care? b) Undiscovered products Biodiversity why care? c) Ecosystem services Fig Madagascar periwinkle: Chemo drugs 1998 Flood prevention Pollination Fig

6 Biodiversity why care? d) Ecotourism Biodiversity why care? Beneficial wild genetic diversity for crops Medicinal purposes Ecosystem services (i.e., pollination) Tourism 2. Aesthetic arguments 3. Intrinsic value arguments 4. Ecological arguments Ecological arguments: Disrupting communities Types of community interactions: 1. Mutualism: Both species benefit from interaction Community: Interactions between different species living in same place at same time Pollination Extinction has consequences for other species The first rule of intelligent tinkering is to save all the parts Mycorrhizae: Fungus-root Fig Fig 14.11, 12 Types of community interactions: 1. Mutualism: Both species benefit from interaction Types of community interactions: 2. Predation: One species benefits Fig

7 Types of community interactions: 3. Competition: Negative for both species Types of community interactions: 3. Competition: Negative for both species Hyenas and lions Chick gut is empty Salmonella bacteria have no competition Chick fed good bacteria Salmonella bacteria have competition Limits pop. size Fig Mutualism Ecological arguments: Keystone species Predation Competition Species has disproportionately large effect on its environment Table 14.1 Fig 14.9 Black-tailed prairie dog 7

8 Historically: Federal poisoning programs Wolf: Another keystone species Fig Wolves indirectly help beaver by decreasing elk Wolves Elk Aspen Competition with beaver 8