Principles of Ecology

1. 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. 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. 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 Carnivores vs. Omnivores

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. 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 Key Terms