What is Ecology?

1. What is Ecology?

2. Ecology is the scientific study of interactions among organisms and between organisms and their environment, or surroundings.

3. The largest component of the living world is the biosphere. The biosphere contains the combined portions of the planet in which all of life exists, including land, water, and air or atmosphere. It extends about 8 kilometers above Earth’s atmosphere to as far as 11 kilometers below the surface of the ocean.

4. Levels of Organization • The study of ecology ranges from the study of an individual organism to populations, communities, ecosystems, biomes and the biosphere.

6. Levels of Organization • Organism – individual living thing • Population – group of organisms of one type that live in the same area • Community – populations that live together in a defined area • Ecosystem – community and its nonliving surroundings • Biosphere – part of Earth that contains all ecosystems

7. The Flow of Energy

8. Organic compounds – compounds that have both carbon and hydrogen atoms together • eg. CH4, C6H12O6 • Inorganic compounds – do not contain carbon & hydrogen together • eg. CO2, H2O, O2, NaCl

9. Producers • The main source of energy for life on Earth is sunlight. • Some types of organisms rely on the energy stored in inorganic chemical compounds. • These organisms are called autotrophs because they use energy from the environment to assemble simple inorganic compounds into complex organic molecules. They can also be called producers.

11. Photosynthesis – light energy is used to power chemical reactions that convert CO2 and H2O into O2 and energy rich carbohydrates • Chemosynthesis – use energy stored in chemical bonds to produce energy-rich carbohydrates

12. Consumers • Organisms that rely on other organisms for their energy and food supply are called heterotrophs. • Heterotrophs are also called consumers.

13. Different Consumers • Herbivores – eat only plants (cows, caterpillars, deer) • Carnivores – eat animals (snakes, dogs, owls) • Omnivores – eat both plants and animals (humans, bears, monkeys) • Detritivores – feed on plant and animal remains and other dead matter, called detritus (mites, earthworms, snails, crabs) • Decomposers – break down organic matter to be recycled (bacteria, fungi)

14. Feeding Relationships • Energy flows through an ecosystem in one direction, from the sun or inorganic compounds to autotrophs (producers) and then to various heterotrophs (consumers)

15. Food Chain - series of steps in which organisms transfer energy by eating and being eaten

16. Feeding Relationships • Food Web - a network of complex interaction. Links all food chains in an ecosystem together • Trophic Level – each step in food chain or food web. Autotrophs are 1st trophic level, consumers are 2nd, 3rd, or higher trophic levels

18. Ecological Pyramids • A diagram that shows the relative amounts of energy or matter contained within each trophic level in a food chain or food web. • Three kinds of ecological pyramids: • Energy pyramid • Biomass pyramid • Pyramid of numbers

19. Energy Pyramid • Only 10 percent of energy available at each trophic level is transferred to organisms at next trophic level

20. Biomass Pyramid • Total amount of living tissue within a given trophic level

21. Pyramid of Numbers • Numbers of individual organisms at each trophic level. (Forest ecosystems may have one tree for many insects)

22. Ecological pyramids show the decreasing amounts of energy, living tissue, or number of organisms at successive feeding levels. The pyramid is divided into sections that represent each trophic level. The area of each level symbolizes the amount of energy or matter remaining at that level.

23. Cycles of Matter

24. Cycles of Matter • Energy flows in only one direction in an ecosystem. Matter is recycled within and between ecosystems. • This is done through biogeochemical cycles. • Cycles of Matter

25. The Water Cycle

26. The Water Cycle • Evaporation – process by which liquid water changes to water vapor • Transpiration – process by which water evaporates from leaves of plants • Condensation – process by which water vapor changes to liquid water • Runoff – process by which water flows over the surface of the ground • Precipitation – process by which water, in any form, falls from the atmosphere to the Earth’s surface • Seepage – process by which water soaks into the ground

27. Nutrient Cycles • Every living organism needs nutrients to grow and carry out essential life functions. Like water, nutrients are also recycled

28. The Carbon Cycle

29. The Nitrogen Cycle • Nitrogen Fixation – only certain types of bacteria can use nitrogen from the air. They live in the soil and on the roots of plants called legumes. They convert nitrogen gas into ammonia in the process of nitrogen fixation. Other bacteria convert the ammonia into nitrates and nitrites that can be used by producers to make proteins.

30. Decomposers return nitrogen to soil as ammonia – producers then take it in • Other bacteria convert nitrates into nitrogen gas in denitrification. Nitrogen gas then returns to atmosphere

31. The Nitrogen Cycle

32. What Shapes an Ecosystem?

33. Biotic and Abiotic Factors • Ecosystems are influenced by a combination of biological and physical factors • Biotic factors – include all living things with which an organism might interact (birds, trees, bacteria, mushrooms) • Abiotic factors – physical or nonliving factors that shape an ecosystem (wind, nutrient availability, temperature, precipitation)

34. Together, biotic and abiotic factors determine the survival and growth of an organism and the productivity of the ecosystem in which the organism lives. • The area where an organism lives is its habitat.

35. Carrying Capacity • Carrying Capacity is the greatest number of individuals of a particular species that an environment can support. Varies depending in the species, the time of year and food availability

36. Limiting factor – unfavorable factor such as temperature, disease, predation that prevents organisms from achieving their biotic potential

37. Limiting Factors

38. Niche • Full range of physical and biological conditions in which an organism lives and the way in which the organism uses those conditions. • No two species can occupy the same niche.

40. Community Interactions • Competition – when organisms of the same or different species attempt to use an ecological resource in the same place at the same time. • eg. Two trees competing for sunlight, two lizard species competing for the same food, two members of same species competing for a mate

41. Community Interactions • Predation – one organism captures and feeds on another • eg. Cheetah (predator) chases and kills an antelope (prey)

42. Community Interactions • Symbiosis – two species living closely together. Three classes: mutualism, commensalism, parasitism • Mutualism – both species benefit (bees pollinating flowers, birds on rhino, termites & protozoans) • Commensalism – one species benefits while other is unharmed (orchid in tree, remora on shark, barnacles on whale) • Parasitism – one species benefits while the other is harmed (tick on deer, leech on human, tapeworm in mammals)

43. Symbiotic Relationships Mutualism—both species benefit (top left ): The ant cares for the aphids and protects them from predators. The aphids produce a sweet liquid that the ant drinks. Commensalism—one species benefits; the other is neither helped nor harmed (top right): The orchid benefits from its perch in the tree as it absorbs water and minerals from rainwater and runoff, but the tree is not affected. Parasitism—one species benefits while the other is harmed (bottom): A flea feeds on the blood of its host, which can be harmed by diseases the flea carries.

44. Ecological Succession • Ecosystems are constantly changing in response to natural and human disturbances. As an ecosystem changes, older inhabitants gradually die out and new organisms move in, causing further changes in the community – this is known as ecological succession.

45. Primary succession – succession that occurs on surfaces where no soil exists eg. new islands built from volcanic eruptions, land covered by lava, bare rock exposed by glacier. • First species to populate are pioneer species. Often lichens

47. Secondary succession – changes that occur in an existing community without removing the soil. eg. land cleared and plowed but left abandoned, wild fires burning woodlands Climax community – final community which is stable, complex and tends to stay the same unless disturbed

48. Ecological Succession