Biology: The Study of Life

1. Biology: The Study of Life • “Bio”- living, life • “Logos”- knowledge/study

3. 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

4. Organization of the Biosphere • Many types of ecosystem • Tundra • Tropical rainforests • Deserts • Kelp forests • Coral reefs

5. 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

6. 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

7. Ecosystems are dynamic environments • Organisms exchange materials and energy with their environment • Energy and nutrients are cycled through

8. Ecosystems are characterized by: • Cycling of materials How do humans impact this?

9. Ecosystems are characterized by: How do humans impact this? • Flow of energy • Food chains • Food webs

10. 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

11. 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

12. 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

13. 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

14. 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?