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. CO 2 released back into atmosphere from respiration. –In the beginning…lots of CO 2, 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 –N 2  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 N 2 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.