Chapter 35 Population

1. Chapter 35 Population

2. Population Density • Population-members of the same species living in a specific area • Population density– The number of individuals of a particular species divided by area or volume. Ex: the number of fish per square kilometer of swamp Pop. Density = # of Individuals Unit Area

3. Population Density • Example: • What is the population density if there are 500 people in a 100km2 area? • 500/100 = 5 people/km2

4. Niche • Niche – An organisms unique living place defined by food, habitat, activity times, breeding, etc. • A habitat is an organism’s environment (biotic and abiotic). • No two species can occupy the same niche. But they can occupy the same habitat.

5. Predation - one organism eats another. Predators are the organisms • doing the eating. • The organism being eaten • is the prey.

6. Symbiotic Relationships • Symbiosis - A close interaction between two species. • Ex: the clown fish and sea anemone.

7. Types of symbiotic relationships • Parasitism: 1 benefits, the other is harmed (tapeworm in intestinal tract) • Mutualism: Both benefit. (Us and bacteria in our intestinal tract) • Commensalism: 1 benefits, the other not affected (crab which uses seaweed for camouflage)

8. Symbiosis

10. Disturbances in Communities • Ecological succession: Process of community change. • Primary succession: a community arises out of a formerly lifeless area (no soil). Ex.:New islands

11. Secondary succession: a community changes after a dramatic change in an area where there is soil. • Fire, volcano, clearing forest

12. Introduced species – humans move species from native location to new areas they’re not native to. Ex: Kudzu, Brazilian Pepper plant. Kudzu kills other plants by smothering them under a solid blanket of leaves, by girdling woody stems and tree trunks, and by breaking branches or uprooting entire trees and shrubs through the sheer force of its weight. Once established, Kudzu plants grow rapidly, extending as much as 60 feet per season at a rate of about one foot per day

13. Energy Flow • How an organism feeds determines the path of energy in the ecosystem. • Producers (autotrophs): organism that makes if own food. Ex: Plants • Consumers (heterotrophs): organisms that eat producers • Ex: Animals, bacteria

14. Consumers Consumers may be: • Herbivores: animals that eat plants • Ex: Cows • Carnivores: animals that eat other animals. Ex: Lions • Omnivores: eat plants and animals • Ex: Humans • Decomposers: organism that breaks down organic waste • Ex: Bacteria and fungi

15. Consumer - Decomposer

16. Consumers • Also categorized by their position in a particular food chain. • Primary consumer: when a consumer feeds directly on producers • Secondary consumer: • eat primary consumers • Tertiary consumers: • third level, eat secondary • consumers

17. Trophic Levels Trophic level: feeding level in the ecosystem Food chain: the pathway of food transfer from one trophic level to another Food web: A pattern of feeding in an ecosystem consisting of interconnected and branching food chains.

18. Trophic Levels

19. Food Chain

20. Food Web

21. Energy Flows Through Ecosystems Ecological Energy Pyramids: • Illustrates how the energy transfers between trophic levels -only 10% of the energy of the previous trophic level is utilized by the next level • 90% is lost as heat.

22. Biological Magnification • Pollutants become more and more concentrated as they move up the food chain • Pollutants concentrate in the muscle, which is eaten. As organisms consume more and more contaminated muscle much pollutant accumulates in their tissues. • Example: see fig 36-17 PCB’s and DDT pg. 802

23. Threats to Biodiversity • Habitat destruction is the number one threat to biodiversity • Other threats to biodiversity • Introduced species (like kudzu in Florida) • Habitat destruction • Overexploitation (killing elephants for ivory) • Pollution

25. Nutrients Cycle Through Ecosystems • Carbon cycle • During cellular respiration consumers break down sugars and release carbon dioxide into the atmosphere • During photosynthesis producers take in carbon dioxide and form sugars

27. Water Cycle • Condensation-gaseous water becomes liquid water. • Precipitation-raining • Transpiration-water exits the leaves • Evaporation-liquid water becomes gaseous water. -

28. Nitrogen Cycle • Nitrogen in the atmosphere • Nitrogen cycle relies heavily on bacteria. • Bacteria convert ammonium into Nitrates (NO3¯) in the soil for plants to use. • Animals eat plants and get Nitrogen.

29. Human Impacts on the Environment • Burning of fossil fuels • Greenhouse effect - Carbon dioxide gets trapped in the atmosphere and causes the Earth to heat up. • Caused by the destruction of the ozone layer by chlorofluorocarbons or CFC’s • In excess this can lead to global warming

30. LET’S REVIEW • What is a producer? • Organism that makes its own food (plants) • What is a consumer? • Organism that eats producers (animals) • How do producers fit into the food chain? • Producers supply all the energy. • How does a herbivore differ from a carnivore? • Herbivore –eats only plants • Carnivore – eats only meat • What is an omnivore? • Eats both plant and meat • In which category of consumers would we find bacteria? • Decomposer

31. 7. How does a food chain differ from a food web? • Food chain shows one energy pathway – food web shows interconnected energy pathways • Explain the rule of 10%. In a food chain, 10% of the energy made by the producers is available to the consumer (trophic level above it) 90% of the energy is lost as heat. 9.What causes the greenhouse effect? CO2 gets trapped in the earth’s atmosphere caused by destruction of the ozone layer by CFC’s 10. Why is it bad to spray DDT on crops? • Biological Magnification 11. What is the #1 threat to biodiversity? • Habitat destruction