Chapter 3 The Principles of Ecology 1 2 I- The Beginning of Ecology Natural history lead to ecology • Science that studies the interaction between organisms and their environment • Combines knowledge between many sciences: Biology, chemistry, physic and earth science I- B. The living Environment: Biotic factors 3 • All living things are found in a layer called the Biosphere • Biosphere is made up of different environments : Aquatic / Terrestrial • Environment consist of –Nonliving factors ( Abiotic factors) –Living factors ( Biotic factors) 4 I- C. Abiotic Factors • Abiotic factors can have obvious effects on living things and often it determines which species can survive. • Example: Grasslands only support small plants and many grassing animals 5 II- Levels of Organization • All organisms depend on others for food, shelter, reproduction or protection. • Ecologist study interaction among organisms at several different levels. • Levels of organization provide a tool to use in planning their research. –Example: Studying bees Vs. foxes 6 Levels of organization. Page 59 • • • • • Individual Populations Communities Ecosystem Biospheres 7 II- A. Interaction within Populations KINDS OF COMPETITIONS: • among individuals in a population • between populations in a community • between communities in an Ecosystem HOW TO AVOID COMPETION • Alternating generation • Metamorphosis 8 ALTERNATING GENERATION METAMORPHOSIS 9 II- B. Individuals interact in Communities 10 • No population or organisms lives independently of other species. • Community is a collections of interacting populations • Change in one population causes change in another –Example: more people less vegetation 11 II- C. Interaction between Abiotic and Biotic factors • Ecosystems are interaction among the populations in a community and their physical surroundings. • Kinds of ecosystems: –Terrestrial –Aquatic ( 75% of earth’s surface) 12 II- D. Where and how organisms live • Every organism plays a role in their community • All help maintain a balance (Homeostasis) • Role played is the organism’s NICHE • Habitat is place where organism lives –many species usually share habitats 13 III- How organisms Interact Feeding relationships: How organisms obtain energy • Autotrophs = capture and store light energy • Heterotrophs = depend on autotrophs for a food source • Carnivores = organism that depends on other heterotrophs as a food source 14 III- How organisms Interact part 2 • Scavengers = depend on dead organisms as food source • Omnivores = eat a variety of food both plants and animals • Decomposers = break down and absorb nutrients from dead organisms 15 III- B. Close relationship for survival • Symbiosis : close and permanet association between organisms of different species. • Commensalism: one species is benefited and the other is neither helped or harmed • Mutualism: both species benefit • parasitism: one benefits at the expense of the other 16 III- B. Close relationship for survival • more Symbiotic relationships –parasitism: one benefits at the expense of the other 17 IV- A. Matter & Enery in Ecosystem • Food Chain –each link provides less energy then the previous. (energy loss by heat and motion) –3links in a food chain good / 5 are bad –each level or link is called a Trophic level –many food chains cross and interconnect this is called a (Food Web) Food Web 18 19 Pyramid numbers 20 Energy Pyramid IV- C. Cycling maintains Homeostasis • • • • Water cycle Carbon dioxide cycle Nitrogen cycle Phosphorus cycle 21 22 Water cycle 23 Carbon Dioxide cycle 24 Nitrogen cycle