Transcript ppt lecture
Biology: The Study of Life “Bio”- living, life “Logos”knowledge/study 1 2 Human Impact: Humans are members of the Biosphere Biosphere Entire portion of planet where life occurs from the upper atmosphere to ocean floor and below Ecosystem Consists of all the organisms living in a particular area (plants, animals, bacteria) as well as all the nonliving, physical components of the environment with which the organisms interact (air, soil, water, sunlight) Ex: marsh, forest, mountain lake, desert 3 Organization of the Biosphere Many types of ecosystem Tundra Tropical rainforests Deserts Kelp forests Coral reefs 4 Organization of the Biosphere Major determinant of which ecosystem is found where is climate Deserts = low rainfall Tropical rainforests = wet & warm Coral reefs = shallow, clear warm oceans Reefs and tropical rainforests are both homes to wide diversity of organisms 5 Within an Ecosystem: Community: All living organisms in an ecosystem Organisms in communities interact with one another and are often strongly dependent upon one another (form food webs, etc) Population: All members of same species which may mate with one another within an area Many populations in one community 6 Ecosystems are dynamic environments Organisms exchange materials and energy with their environment Energy and nutrients are cycled through 7 Ecosystems are characterized by: Cycling of materials How do humans impact this? 8 Ecosystems are characterized by: Flow of energy Food chains Food webs How do humans impact this? 9 Human Population Human activities shape ecosystems cut down forests plow grasslands drain marshes build houses and roads Redirect water Activities often result in pollution that changes ecosystems Effects are particularly bad in rainforest and coral reefs 10 Human Population Human activities have Destroyed > 10% of coral reefs and damaged another 30% Cut down rainforests Polluted water Harming ability of world’s ecosystems to support us, our children and other species Just starting to realize how strongly we depend on our ecosystems We may be changing our planet in unforeseen, negative ways 11 Biodiversity Biodiversity = number of species, and their genetic variability Between 2 and 20 million species alive today Human activities threaten many of them Hundreds of species go extinct every day Many more have been reduced to a very small number of individuals 12 Biodiversity Each individual has only two sets of chromosomes Each can carry only 2 copies of the gene for any trait Fewer individuals = less genetic diversity Natural selection acts on diversity If individuals don’t have needed traits to survive in environment, all will die Fewer genetic options = more likely extinction is as environment changes 13 Biodiversity Loss of species and loss of genetic diversity in today’s ecosystems is worrying Are human activities leading to a “mass extinction” like the one 65 million years ago when the dinosaurs all died? 14