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Ecosystems

Explore the levels of organization within ecosystems, defining species and their characteristics, population dispersal patterns, ecological niches, generalist vs. specialist species, the Law of Tolerance, resource partitioning, and the role of keystone species in maintaining ecosystem balance.

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Ecosystems

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  1. Ecosystems Part 1

  2. Levels of organization

  3. Levels of organization

  4. What is a species? • Basic unit of biological classification • Organisms that resemble each other, that are similar in genetic makeup, chemistry, and behavior, and that are able to interbreed and produce fertile offspring

  5. Is it a species?

  6. Vocab • Intra = “within” • Intraspecific interactions = ?? • Inter = “Between” • Interspecific interactions = ??

  7. Population Dispersal patterns • Clumped – most individuals are together • In environments with patchy resources • Most common in nature • Random – little interaction between members of a species • In environments with consistent resources • Uniform – found when distance between neighbors is maximized • Arises from competition for a resource

  8. Population dispersal patterns – the visual

  9. Ecological Niches • Definition: ??? • Influenced by the physical environment • Take into account: • Interactions with the biotic and abiotic environment • Available resources • To describe: • Organisms adaptive traits • Habitat • Place in the food web

  10. Generalist vs. specialist • Generalist: live in broad niches and withstand a wide range of environmental conditions • (K-selected) • Specialist: live in narrow niches and sensitive to environmental change • (r-selected) • Who has the advantage in the environment?

  11. Law of Tolerance • The existence, abundance, and distribution of each species depends on the species tolerance to both the physical and chemical factors of the environment • Limiting factor: any factor in the environment that limits the growth of a population

  12. Resource partitioning • Species “share” a resource and avoid direct competition with each other • Types: • Temporal: use resource at different times • Spatial: use the resource in different areas • Morphological: evolves different characteristics to use the resource

  13. Ecosystem Community Characteristics • Physical appearance: relative size, stratification, distribution of the populations and species • Species diversity: number of different species • Species abundance: number of individuals of each species • Niche structure: number of ecological niches, how they resemble or differ from each other, species interactions

  14. Biological Interactions amongst species

  15. Biological Interactions amongst species

  16. Biological Interactions amongst species

  17. Key Stone Species • A species whose presence contributes to the diversity of life and whose extinction would lead to extinction of other forms of life • Dramatic shifts in the ecosystem can occur when a keystone species is removed

  18. Sea Stars “Starfish” Sea stars prey on muscles, urchins, and other shell fish When removed muscle populations explode and out compete other organisms Sea urchins rise to the point they destroy coral reefs Sea Otter Prey on sea urchins Sea urchins eat through kelp holdfasts, which anchor the kelp to the ground, causing entire kelp forests to float away Keystone species examples

  19. Wolves in Yellowstone • Homework: • Download the article from my website • Read and annotate • # paragraphs • Highlight main ideas • Write a one paragraph summary

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