Transcript Chapter 5
Chapter 5 Ecological Concepts Environment: – abiotic – biotic Ecosystems are the most complex level of biological organization: – cells, tissues, organs, organisms, populations, communities, ecosystems. • Limiting Factors • range of tolerance • acclimation Chapter 5 Habitat and Niche • The “Where” and the “How”. • Habitat: • “Where” organisms lives. • Niche: • Includes space, food, temperature, conditions for mating, etc. • Also takes into account behavior at various seasons or times of day. • Niche is not synonymous with habitat Chapter 5 Natural Selection & Evolution • Within species speciation • Charles Darwin • Organisms change relative to one another over time. • Browsing plants evolve in relation to herbivores. • Herbivores adapt for food. • Pesticides and Insects Chapter 5 Organismal Interactions • Competition: • intraspecific competition: – competition between individuals of a single species. • interspecific competition: – competition between two different kinds of organisms. • Competitive Exclusion Principle – “No two species can occupy exactly the same niche indefinitely” Chapter 5 Predation: • Predation limits size of populations. • Prey must survive in at least small numbers or predator becomes extinct. • Prey evolves to have unique defenses against predator. Chapter 5 Symbiotic Relationships: • Two different species (partners) live in physical contact with each together. • Parasitism: • one partner benefits, other is harmed (special form of predation). – parasite - benefits – host – harmed “ecto” & “endo” parasites: • internal parasites are more specialized Chapter 5 Commensalism: • One partner benefits, other neither benefits nor is harmed. • Individuals of one species physically attached to individuals of other species. Mutualism: • both partners benefit. – example: ants and acacia – example: mycorrhizae fungi and plant roots Chapter 5 Community & Ecosystem Interactions Ecosystem Roles: • Producers • Consumers – primary – secondary • • • • carnivores omnivores scavenger parasite • Decomposers Chapter 5 Ecosystem Energetics • trophic levels – Each step in the flow of energy through an ecosystem is known as a trophic level – analogous to ecosystem roles • energy at each level can be estimated by measuring biomass Food Chain/Food Web producer (convert about 1% of suns energy to organic energy) • consumer(90% loss of that energy at each step) • decomposer Chapter 5 Biogeochemical Cycles • All substances in organisms cycle through ecosystems. • Bulk of substances are not contained within the bodies of organisms. • Organisms must be able to move these substances from abiotic into biotic systems. Chapter 5 Carbon Cycle • Based on atmospheric carbon dioxide. (0.03% of air) • Plants (and some bacteria) make 70 billions tons of organic compounds yearly. • CO2 released back into atmosphere from respiration. – In the beginning…lots of CO2,Planet inhospitable to people, plants ruled, carbon sequestered as coal/oil, oxygen created, climate more hospitable to human. Cycle balanced for millennia. Now burning fossil fuels, cutting of forests, etc means carbon is released back to atmosphere…impacts? Chapter 5 Nitrogen Cycle • Protein is an organic compound with nitrogen (e.g. amino acid). • Nitrogen constitutes about 78% of air. • Very few organisms can convert nitrogen gas into biologically useful forms. – – – – – Humans use lots-o-energy to make fertilizer nitrogen-fixers free living and symbiotic bacteria N2 ammonia Decomposers break other N-compounds into ammonia as well Chapter 5 Nitrogen Cycle (cont’d) • Nitrifiers – two different groups of bacteria working in sequence – ammonia nitrite nitrate • Plants then use nitrate • Denitrifying Bacteria – Take nitrite to N2 gas—goes back to atmosphere • Nitrogen is essential to life—require micro-organisms and bacteria to cycle Chapter 5 Phosphorous Cycle • Originates in rock, dissolution of rock releases into water and soil. – Bat/bird guano harvested for P content • Needed in life for nucleic acids and ATP. – Plants take it in through roots. – Animals eat plants. – Decomposers return it to soil.