1. Ecology An Introduction to Ecology and the Biosphere

2. The Scope of Ecology  High in the sky, a series of satellites circle Earth.  These satellites aren’t relaying the chatter of cell phones.  They are transmitting data on the annual migration of gray whales.

3. The Journey of Gray Whales  Leaving their calving grounds near Baja California, adult and newborn gray whales (Eschrichtius robustus) swim side by side on a remarkable 8,000 km journey.

4. Headed to the Arctic  The whales are headed to the Arctic Ocean to feed on the crustaceans, tube worms and other creatures that thrive there in the summer.  Satellites track their progress.

5. Recovery from Brink of Extinction  Satellites also help scientists track the recovery of the blue whale from extinction.  A century ago, whaling had reduced the population to only a few hundred.  Today, after 70 years of protection, more than 20,000 travel to the Arctic each year.

6. Questions for Ecologists:  What environmental factors determine the geographic distribution of gray whales?  How do variations in their food supply affect the size of the gray whale population?

7. What is Ecology?  “oikos” = home, “logos” = to study  The scientific study of the interactions between organisms and the environment.

8. Studying Ecology at the Organism Level:  Studies how an organism’s structure, physiology, and (for animals) behavior meet the challenges posed by its environment.  Ex: How do hammerhead sharks select a mate? Organism: an individual form of life that has the ability to act or function independently.

9. Population Ecology  A population is a group of individuals of the same species living in an area.  Population ecology analyzes factors that affect population size and why it changes through time.  Ex:What is the carrying capacity of the Kaibab Forest whitetail deer population?

10. Community Ecology  A community is a group of populations of different species in an area.  Community Ecology examines how interactions between species, such as predation and competition, affect community structure and organization. Ex: What factors influence the diversity of species that make up a forest?

11. Ecosystem Ecology  An ecosystem is the community of organisms in an area and the physical factors with which those organisms interact.  Ecosystem Ecology emphasizes energy flow and chemical cycling between organisms and the environment. Ex: What factors control photosynthetic productivity in the savannah grassland of Africa?

12. Biome Ecology  A biome is a large region characterized by a specific kind of climate and certain kinds of plant and animal communities.  Biome Ecology focuses on the weather and climate patterns of an area (biogeography) that determines what kinds of organisms live there. Ex: How would a drought affect the population of Black-footed Ferrets in the prairie?

13. Global Ecology  The biosphere is the global ecosystem-the sum of all the planet’s ecosystems.  Global Ecology examines how the regional exchange of energy and materials influences the functioning and distribution of organisms across the biosphere. Ex: How does ocean circulation affect the global distribution of crustaceans?

14. Now You Try!  What level would a biologist be studying if he/she were: -Counting the number of offspring born to a pride of lions? -Observing how a drought affects the number of blossoms on a Saguaro cactus? -Determining the effects of warming ocean temperatures on krill populations in the Antarctic? -Observing the behavior of Arctic wolves as they hunt migrating caribou in the Arctic?

15. What would an example be of the following?  Individual organism  Population of that organism  Community of that organism  Ecosystem of that organism  What biotic (living) factors and abiotic (nonliving) factors would influence where and how that organism lives?  What are the limiting factors in that ecosystem?

16. Biotic Factors in an Ecosystem  Biotic Factors in an ecosystem include those related to the activities of living things. Ex:  Food availability  Diseases & parasites  Density of the population  Human influence

17. Abiotic Factors in an Ecosystem  Nonliving factors that affect population size are abiotic factors.  Weather & Climate  Availability of Sunlight  Availability of Water  pH of water/soil  Wind  Rocks/soil/mountains

18. Habitat (an organisms’ address)  Habitat=the area where an organism lives.  This includes the biotic and abiotic factors that affect it. What is the habitat for this bullfrog?

19. Niche (an organisms’ occupation)  Niche=full range of physical and biological conditions in which an organism lives.  It also includes the way in which the organism uses those conditions.  What makes up the niche of this bullfrog?

20. Does feeding by sea urchins limit seaweed distribution?  W.J. Fletcher, of the University of Sydney, Australia, reasoned that if sea urchins are a limiting biotic factor, then more seaweeds should invade an area from which sea urchins have been removed.  To isolate the effect of sea urchins from that of another seaweed-eating animal, the limpet, he removed only urchins, only limpets, or both from study areas adjacent to a control site.

21. Both limpets and urchins removed Only urchins removed Only limpets removed Control-neither species removed Seaweed Cover 100% 80% 60% 40% 20% 0% Time-August 1983-February 1984

22. Conclusion  Removing both limpets and urchins resulted in the greatest increase in seaweed cover, indicating that both species have some influence on seaweed distribution.  But, since removing only urchins greatly increased seaweed growth while removing only limpets had little effect, Fletcher concluded that sea urchins have a much greater effect than limpets on limiting seaweed distribution.