1. Organisms and their environments
Principles of Ecology
Organisms and their environments

2. Natural history led to ecology
Definition of ecology – scientific study of interactions between organisms and their environments
Ecologists use descriptive and quantitative research
Gather information about relationships such as how day length influences bird migration

3. Biotic Factors Biosphere is portion of the Earth that supports life
All living organisms that inhabit an environment

4. Abiotic Factors Nonliving parts of the environment
Examples: air currents, temperature, moisture, light, and soil
Have obvious effects on living things and often determine which species can survive in a particular environment

5. Levels of Organization
All organisms depend on others for food, shelter, reproduction, or protection
Celltissueorgan system organism population community ecosystem biosphere

6. Interactions within populations
Definition: group of organisms of one species that interbreed and live in the same place at the same time
Competition for food, water, mates, and other resources may determine size of population
May have adaptations to reduce competition (life cycle stages)

7. Interactions within communities
Made up of several populations
No population of organisms of one species lives independently of other species
A change in one population in one community will cause changes in the other populations
Ex: Hawks and mice

8. Interactions among biotic and abiotic factors form ecosystems
Ecosystem is made up of the interactions among the populations in a community and the community’s physical surroundings
Terrestrial, saltwater,
aquatic

9. Where and how populations live
Niche – the role a species plays in a community
Ex: space, food, and other conditions an organism needs to survive and reproduce
Habitat – place where an organism lives out its life
Several species may share a habitat

10. How Organisms Interact
Principles of Ecology
How Organisms Interact

11. Feeding relationships
Autotrophs – organisms that use energy from the sun or energy stored in chemical compounds to manufacture their food
Heterotrophs – organisms that depend on autotrophs as their source of nutrients and energy

12. Carnivores vs. Omnivores
Heterotrophs eat other heterotrophs
Scavengers – feed on carrion, refuse, and dead organisms
Heterotrophs eat both animal and plant material
Decomposers – break down complex compounds of dead and decaying plants and animals

13. Close relationships for survival
Symbiosis – close and permanent association between organisms of different species
Commensalism +/N (Spanish moss)
Mutualism +/+ (ant and acacia tree)
Parasitism +/- (dog and tapeworm)

14. Matter and Energy in Ecosystems
Food Chains – a simple model that scientists use to show how matter and energy move through an ecosystem
Algae  fish  heron
Three to five links due to amount of energy left by the fifth link (small due to loss of heat at each link)

15. Trophic levels
Passage of energy; represents a feeding step in the transfer of energy and matter in an ecosystem
Level 1 - producers
Level 2 -first order consumers – herbivores that feed on producers
Level 3 – second order consumers - carnivores

16. Food Webs
Expresses all all the possible feeding relationships at each trophic level in a community

17. Energy pyramid Show energy use in an ecosystem
Higher trophic levels are laryered on top and amount of energy decreasing as moves upward
Source of all energy - SUN

18. Cycling maintains homeostasis
Matter in the form of nutrients, moves through the organisms at each trophic level
Matter cannot be replenished like energy from sunlight
Matter is constantly recycled

19. Water Cycle

20. Carbon Cycle

21. Nitrogen Cycle

22. Phosphorus Cycle

23. Key Terms Abiotic factor Autotroph Biosphere Biotic factor
Commensalism
Community
Decomposer
Ecology
Ecosystem
Food chain
Food web
Habitat
Heterotroph
Mutualism
Niche
Parasitism
Population
Scavenger
Symbiosis
Trophic level