Ecology & Ecosystems

1. Ecology & Ecosystems Objectives: Contrast exponential and logistical growth. Differentiate r and k strategies of reproduction. Summarize the Hardy-Weinberg principal. Distinguish and ecosystem from a community. Describe the process of succession. Distinguish between producers and consumers. Compare food webs and food chains.

2. Ecology • Ecology is the scientific study of interactions between life forms and their environment. Shenandoah Mountains, VA

3. The Dead and Alive • Biotic – living organisms in an ecosystem. • Abiotic – non-living matter in an ecosystem. Examples: air, and rocks.

4. The Niche The area in which an organism lives including all the living and nonliving matter it needs to survive. Shenandoah Mountains, VA

5. Population Density • Population density is the number of organisms per unit area.

6. Population Growth Rates Three factors affect population size: • Number of births • Number of deaths • Number that enter or leave a population

7. Entering a Population • Immigration – movement into a population that increases population size.

8. Leaving a Population • Emigration – The movement of individuals away from the population that causes a decrease in population size. (“E” for exiting, “I” for increases.)

9. Exponential Growth • Occurs under ideal conditions with unlimited resources the population will grow exponentially. The graph to the left shows a population growing by and unlimited number of births, and unlimited numbers of organisms entering the population.

10. Logistic Growth • Unlimited resources are simply not available, so growth is limited. The graph to the left shows a population that has reached a carrying capacity and the population growth rate has slowed due to limited food, space, or water resources.

11. Carrying Capacity • The number of individual species an environment can support given the available resources such as food or space.

12. Growth Strategies • There are two ways animals reproduce to ensure their young survive to adulthood: • R-Strategy – Reproduce large numbers and only a few survive to adulthood. Ex. Sea Turtles, and Roaches. • K-Strategy – Reproduce small numbers and young will usually survive to adulthood. Ex. Humans, and Whales.

13. Density-Dependant Factors • ANY factor that depends on population size. • Density-Dependant factors are caused by - As population increases, so does: • Competition • Predation • Parasitism and Disease

14. Density-Independent Factors • Effect all populations regardless of size. • Density-Independent factors may cause a large drop in population size. • They are caused by: • Unusual Weather • Natural Disasters • Seasonal Cycles • Human Activities like deforestation.

15. Examples of Factors that Limit Population Growth:

16. Organization • One organism is a species. • Groups of species are populations. • Groups of different populations of animals are communities. • Groups of different populations of animals and their nonliving environment is an ecosystem. • Groups of ecosystems make up a biome.

17. 3 Types of Community Interactions • Competition – Two organisms fighting for one resource. • Predation – Hunter and Hunted. • Symbiosis(has 3 different types) Mutualism – both benefit Commensalism – one benefits other is not affected. Parasitism– one benefits, the other is negatively affected.

18. Types of Succession • Primary Succession: Pioneer species are the first to colonize an area with available space. • Secondary Succession: Organisms growing in an area where growth has been naturally or unnaturally interrupted. • Example: A forest burns down and small trees and grasses are the first to grow out

19. Energy Flow in an Ecosystem • There are two types of organisms who make their own food: • Autotrophs –Use sunlight to produce chemical energy (sugars). • Chemotrophs -Some organisms rely on the energy stored in inorganic chemical compounds from Earth’s crust. Hydrothermal Vent Communities at the bottom of the Oceans contain Chemotrophs.

20. Energy From the Sun • Photosynthesis – The use of light energy to power chemical reactions that produce energy. • On land plants are the main autotrophs or producers. • In the sea the phytoplankton are the main autotrophs or producers.

21. Consumers • Consumers are Heterotrophs – They must eat to obtain energy. • There are five types of consumers: • Herbivores - eats plants only • Carnivores – eats other organisms • Omnivores – eats plants or animals. • Decomposers - feed off of organic matter • Detritivores – feed off of dead organic matter called detritus. (ex. Earth worms)

22. Feeding Relationships • Energy flows through an ecosystem in one direction: • Sun autotrophs heterotrophs. • Energy stored by producers is passed up the food chain.

23. Food Webs • Food webs connect all food chains. • What kind of food web is this?

24. Trophic Levels • Each step in a food chain is called a trophic level. • NOTE: Energy is lost as it travels up the food chain in the form of body heat and other bodily functions from living a normal life. • 1000 pounds of phytoplankton • 100 pounds of zooplankton • 1 pound of small fish • 0.01 pound of shark

25. The Water Cycle

26. The Carbon Cycle

27. Released in an ecosystem: Nitrogen Fixing (Nitrification) Bacteria in the soils leading to Uptake by primary producers. Also, atmospheric Nitrogen Fixation by lightning. Absorbed into an ecosystem: Deposition, Excretion of feces. Denitrification by soil bacteria. Erosion. How Nitrogen is:

29. Phosphorus is taken up by plants, which are eaten by organisms, and when they die the phosphorus returns to the sediments. Phosphorus does not enter the atmosphere. It remains mostly in soils, rocks, and ocean sediments. The Phosphorus Cycle

30. Primary Productivity - the rate in which organisms create organic matter. An ecosystem can be limited by a single nutrient if it is in short supply. When nutrient levels are present in excess blooms of growth occur. (Fertilizing a lawn is giving the grass extra phosphorous and nitrogen for faster growth.) Nutrient Limitation

31. Biomes… • Each biome has its own unique climate and unique organisms. • There are 10 biomes.

32. 10 Biomes • Tropical Rainforest • Dry Tropical Forest • Tropical Savanna • Desert • Temperate Grassland • Temperate Woodland and Shrubland • Temperate Forest • NW Coniferous Forest • Boreal Forest • Tundra

33. Aquatic Ecosystems • Freshwater habitats are limited in space. • Ponds and lakes have 3 habitats in which organism live: • Littoral zone – shallow zone near the shore. • Limnetic zone – the area that is farther away from shore but close to the surface. • Profundal zone – deep-water zone below the limits of light penetration. • An estuary is a body of water that is half salt water, half fresh water. Ex. Mouth of a river. • Plankton – small invertebrate animals.

34. Negative Environmental Effects • Acid Rain- Acidic precipitation. • Ozone Hole - Being destroyed by CFC’s, or chlorofluorocarbons. High in the atmosphere the sun’s ultraviolet radiation breaks up the bonds of the CFC molecule and the resulting molecules eat up ozone. • Global Warming - A natural process. • Greenhouse Effect - Traps excessive heat in the atmosphere by not letting it reflect back into space and is speeding up global warming.

35. Effects on an Ecosystem • Biological Magnification - pollutants magnify as they work up the food chain. Example: 5 small fish contain one DDT molecule each and are eaten by a larger fish. The larger fish now contains 5 DDT molecules. Five larger fish are eaten by a hawk. The hawk now contains 25 molecules of DDT.

36. Biological Magnification

37. The Human Population • The current human world-wide population is around 6 billion people. • About 180 people are added each minute. • Technology helps people not only live longer, but it helps populations grow faster. • The United Nations predicts the world population will stabilize around 9.7 billion people, on or around the year 2050.