interactions populations and communities
play

Interactions: Populations and Communities Population Interactions - PowerPoint PPT Presentation

Interactions: Populations and Communities Population Interactions A population of organisms has properties that are different from those individuals that make up the population Cooperation and competition between individuals contribute


  1. Interactions: Populations and Communities

  2. Population Interactions • A population of organisms has properties that are different from those individuals that make up the population • Cooperation and competition between individuals contribute to these properties

  3. Population Interactions • Relationships among interacting populations can be characterized by positive and negative effects , and can be modeled mathematically

  4. Community Interactions • Classified by whether they help, harm or have no effect on the species involved • Species interactions strongly influence the structure of communities • Community : A group of populations of different species in an area

  5. Examples of Community Interactions • Interspecific competition (-/-) • Predation (+/-) • Herbivory (+/-) • Symbiosis - Parasitism (+/-) - Mutualism (+/+) - Commensalism (+/0)

  6. Interspecific Competition (-/-) • Individuals of different species compete for a resource that limits their growth and survival

  7. Predation (+/-) • An interaction in which one organism captures and feeds on another organism • Predator and prey • What are some advantages of predation? (Think!)

  8. Canadian Lynx and the Hare

  9. Herbivory (+/-) • Interaction in which an organism eats parts of a plant or alga

  10. Plant Defenses Against Herbivory • Chemical defenses – produce chemicals that are toxic or taste bad • Mechanical defenses – prickles, thorns, spines or trichomes • Thigmonasty – responses to touch, leaves curl up or close • Leaf shedding or warning coloration

  11. Symbiosis – Parasitism (+/-) • A symbiotic relationship in which one organism benefits at the expense of the other organism

  12. Symbiosis – Commensalism (+/0) • A symbiotic relationship in which one organism benefits and the other organism is neither helped nor harmed

  13. Symbiosis – Mutualism (+/+) • A symbiotic relationship in which both organisms benefit

  14. Community Interactions • Structure of a community is measured and described in terms of its biodiversity , which is measured in species richness (total number of different species in a community), and the relative abundance of each species present

  15. Community Interactions

  16. Ecosystem Stability

  17. Abiotic and Biotic Factors Affect Stability • The stability of populations, communities and ecosystems is affected by interactions with abiotic and biotic factors • Examples: food chains and food webs, algal blooms, species diversity, population density

  18. Food Chain Stability

  19. Food Web Stability

  20. Algal Bloom • Rapid increase in the population of algae in an aquatic ecosystem • Usually caused by an excess of nutrients, such as phosphorus (abiotic factors) • Why are algal blooms harmful?

  21. Species Diversity Within Ecosystems • Diversity of species within an ecosystem may influence the stability of the ecosystem – Keystone species – Producers – Essential abiotic and biotic factors

  22. Keystone Species • A species that is not necessarily abundant in a community yet exerts strong control on community structure by the nature of its ecological role or niche • Removal of a keystone species often results in the collapse of the ecosystem Examples: Sea otters, sea star, tiger sharks

  23. Pisaster ochraceus

  24. Cooperative Interactions

  25. Competition and Cooperation • Competition and cooperation are important aspects of biological systems • Cooperative interactions within organisms promote efficiency in the use of energy and matter – Cellular level – Multicellular organisms – Populations of unicellular organisms

  26. Cooperative Interactions • Cellular level: Plasma membrane, cytoplasm and, for eukaryotes, the organelles contribute to the overall specialization and functioning of the cell

  27. Cooperative Interactions • Multicellular organisms: specialization of organs contributes to the overall functioning of the organism – Exchange of gases – Circulation of fluids – Digestion of food – Excretion of wastes

  28. Cooperative Interactions

  29. Cooperative Interactions • Interactions among cells of a population of unicellular organisms can be similar to those of multicellular organisms • Interactions increase efficiency and utilization of energy and matter Example: Deep sea vent community

  30. Deep Sea Vent Community • Bacterial community in and around deep sea vents • Chemosynthetic bacteria are the primary producers of the food chains of hydrothermal vents • Symbiosis: chemosynthesizers and respiring heterotrophs

  31. Quorum Sensing • Another example of cooperative interactions between bacteria of the same species and different species • Used to coordinate certain behaviors such as biofilm formation and virulence, based on the local density of the bacterial population

  32. Ecological Succession • Succession : the process of change in the species structure of an ecological community over time – Primary succession – bare rock or sand, no soil present – Secondary succession – soil is established – Pioneer species – the first species to arrive, differ between primary and secondary succession

  33. Primary Succession

  34. Secondary Succession

Recommend


More recommend