Ecology 1: Ecosystems

1. Ecology 1: Ecosystems

2. Levels of Organization • Organism • Ex. an elephant • Population • A group of individuals in the same species, living and interacting in one area • Ex. a herd of elephants in the Serengeti • Community • Multiple populations interacting in one area • Ex. grazing antelope, elephants and giraffes in the Serengeti • Ecosystem • All populations in one area interacting with each other and their non-living environment. • Ex. the Serengeti (all organisms plus climate, nutrients, etc.)

3. Levels of Organization • Biosphere • All areas of the earth from the ocean depths to the atmosphere that support life.

4. Ecological roles • Autotrophs - Producer • makes own food (through photosynthesis or chemosynthesis) • Heterotrophs - Consumer • must eat other organisms for food; • primary (mouse), secondary (fox), tertiary (bobcat) • Herbivore (eats plants) Carnivore (eats meat) Omnivore (eats both) • Detritivore • Organisms that feed on animals remains and dead material (crabs, earthworms) • Decomposer • An organism (ex. fungi or bacteria) that completes the final breakdown of materials in an ecosystem • End of 3.1

5. How does energy enter the ecosystem? • Energy hits the earth in the form of sunlight • Autotrophs convert sunlight (or chemical) energy into organic molecules • Less than 1% of the sun’s energy is converted into organic material • Eventually all energy is lost back to the atmosphere as heat.

6. How does energy move through an ecosystem? • Energy trapped in autotrophs (producers) then gets transferred to heterotrophs (consumers) as one organism eats another • The easiest way to show this is by using a food chain, food web, or food pyramid. • Food chain – series of steps in which organisms transfer energy by eating and being eaten.

7. Food Weblinks all ecosystems in a food chain together

8. Food Pyramids • A food pyramid is designed to show the organisms in an ecosystem, grouped by their feeding position or trophic level(1st=prod, 2nd=herbivores, etc) • Both food chains and food pyramids show that only 10% of the energy at one trophic level makes it to the next trophic level (from the 2nd law of thermodynamics).

9. Primary Productivity • The rate at which new organic material is created in an ecosystem by producers is called the Primary Productivity • The more energy entering the food chain (from producers), the more that can pass up through the levels (only 10% moves up at each level), and as result, the more levels there can be. • Therefore, the ecosystems with the most productive producers have the most levels (ex. rain forest) • In most cases, there are only 3-4 levels. • End of 3.2

10. How do nutrients cycle? • Energy follows a ONE-WAY path • Sun living organisms heat atmosphere • Matter CYCLES through living organisms endlessly • Biogeochemical cycles • Water • Carbon and Oxygen • Nitrogen

11. Water Cycle

12. Carbon and Oxygen Cycle

13. Nitrogen Cycle

14. Niches • Niches vs Habitats • A habitat is the location where a species lives. • Ex. tall grassland/prairie • A niche includes all of the species’ requirements plus its role in the ecosystem. It is determined by all the the abiotic and biotic factors relevant to the species. • Ex. Top predator in prairie areas where gophers live, and the temperature is never below freezing.

15. Niche differences • Organisms can be identified as either • Generalists • Organisms with a broad niche • Eat lots of types of food • Live in many types of environments • Ex. house mice • Specialists • Organisms with a narrow niche • Eat a narrow range of food items • Live in few, specific types of habitats • Ex. panda bear

16. Mutualism • Mutualism occurs when both species benefit • Rhinos and oxpeckers • trees and mycorrhizae, • ants and acacia • Termites and protist • Pollination (Yucca and yucca moth)

17. Parasitism • one organism feeds on/lives on another species • typically host is bigger than parasite • parasites usually do not kill host (weaken them) • parasites need host for food, shelter, etc. • ex. fleas on dog, tapeworm in human, mistletoe, lamprey

18. Commensalism • Commensalism occurs when one species benefits, and the other neither benefits, or is harmed • examples: • clownfish and anemones • epiphytes and trees • Cattle egrets and ungulates

19. Predation • Predation - one organism feeds upon the other • predator usually bigger than prey • ex. lion eating zebra

20. Prey Strategies

21. Competition • When two species use the same resources, they are said to compete and their interaction = competition. • ex. lions and hyenas compete for food in Africa • Competition does not necessarily involve contact; interaction may be only by means of effects on the resources. • No two organisms can occupy exactly the same niche at the same time

22. What determines where species can live? • All species have requirements for many factors/conditions. • Abiotic factors – non-living factors; ex. temperature, precipitation, pH • Biotic factors – other species; ex. prey species, competing species • For each of these factors, species exhibit a range of tolerance. • For example, a fish species may only be found within a pH range of 4.5 to 6 in lakes.

23. Biomes • A major terrestrial community that is found in different areas with similar climate is called a biome. A biome’s structure and appearance are similar throughout its distribution. • The world’s biomes are tropical rain forest, tropical dry forest, temperate woodland and shrubland (Chaparral), temperate deciduous forest, boreal/coniferous forest (taiga), desert, temperate grassland, tropical grassland (savanna), and tundra.

24. Biome distribution

25. Freshwater Habitats • These habitats are distinct from both marine and terrestrial habitats and are very limited in area. • make up about 2% of earth’s surface • can be divided into • Flowing water (rivers) standing water (ponds and lakes) and wetlands (seasonal coverage)

26. Freshwater Habitats • Estuaries • These are very important for • Breeding grounds for fish • Filtering water • Very productive ecosystems! • Disappearing fast (flat land near the ocean)

27. Ocean • 75% of earth’s surface • Continental shelf - shallow ocean waters - smallest area; large number of species (kelp forests) • Intertidal zones • Along our coast • Species can tolerate being in and out of water • Sea stars, algae, sea anemones • Coral Reefs • The “rain forests” of the ocean • High diversity • In tropical waters

28. Ocean • open sea surface - contains plankton (free-floating microscopic organisms), bacteria, algae, fish larvae; responsible for 40% of world’s photosynthesis • Benthic zone - deep sea waters - below 1000’ feet animals adapted to dark; some blind/bioluminescent

29. What happens when ecosystems are disturbed? • When a disturbance impacts an ecosystem, it recovers through a process known as succession. • Succession on newly formed habitat is called primary succession. • No remaining organisms or soil • Examples, lava flow, sand dune, glacier retreat • It can take 1000+ years from sand dune to forest.