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Ecological Concepts and Interactions: Ecosystems, Habitat, Natural Selection, Organismal Interactions, Symbiotic Relatio

This chapter explores various ecological concepts and interactions, including ecosystems, habitats, natural selection, organismal interactions, symbiotic relationships, ecosystem roles, ecosystem energetics, and biogeochemical cycles.

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Ecological Concepts and Interactions: Ecosystems, Habitat, Natural Selection, Organismal Interactions, Symbiotic Relatio

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  1. 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

  2. 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

  3. Chapter 5 Natural Selection & Evolution • Within species è 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

  4. 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”

  5. 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.

  6. 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

  7. 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

  8. Chapter 5 Community & Ecosystem Interactions Ecosystem Roles: • Producers • Consumers • primary • secondary • carnivores • omnivores • scavenger • parasite • Decomposers

  9. 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

  10. 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.

  11. 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?

  12. 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 • N2è ammonia • Decomposers break other N-compounds into ammonia as well

  13. Chapter 5 Nitrogen Cycle (cont’d) • Nitrifiers • two different groups of bacteria working in sequence • ammonia è nitrite è 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

  14. 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.

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