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Ecosystems and Populations

Ecosystems and Populations. Terms. Ecology : study of how organisms interact with each other and their non-living environment ( biotic-living and abiotic-non living factors). Ecosystem : The biotic community and all abiotic factors.

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Ecosystems and Populations

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  1. Ecosystems and Populations

  2. Terms • Ecology: study of how organisms interact with each other and their non-living environment (biotic-living and abiotic-non living factors)

  3. Ecosystem: The biotic community and all abiotic factors. • Community: All the living organisms/populations in an area • Population: group of organisms of same species

  4. Roles in Ecosystems • Habitat: the area where an organism lives; its address (eg. Tropical rainforest); • Niche: an organism’s profession; what it eats, what eats it, the habitat, time when active, etc.

  5. Competition • Having differing niches allows organisms to reduce competition • Eg. Hawks vs. owls

  6. Competition Warblers Yellow rumped – only in bottoms of trees Blackburnian – only at tops of trees

  7. Biodiversity • describes the number and variety of organisms in an ecosystem. • Greater biodiversity means more stability because if one species in a food web is lost, its predator can switch to another prey.

  8. Indicator Species • are species of organisms that provide an early warning that an ecosystem is being affected by some factor. • Usually, these species are very sensitive to changes in an ecosystem, or to specific changes of ecosystem conditions.

  9. Exotic Species • Second only to habitat loss as a cause of extinction • New species occupy niches of natural populations and out compete them purple loosestrife zebra mussels starlings

  10. Species At Risk Less severe risk Special concern – numbers are declining at the range / fringe of the area Threatened – species may become endangered if threatening conditions are not reversed Extirpated – a species no longer exists in one particular area, but is still found in other areas Endangered – a species is close to extinction in all parts of their natural habitat Extinct – a species no longer exists Most severe risk

  11. Labrador duck-1875 Extinct Canadian Species Great Auk -1844 Sea Mink-1870

  12. Genetically Modified Crops • Transfer of genes from one organism to another unrelated organism • Eg. Roundup resistance to canola

  13. Fish antifreeze proteins to strawberries

  14. Vitamin A gene to rice

  15. Green Fluorescent Protein to monkeys/pigs

  16. Biological Control • Using a natural predator to control an unwanted species.

  17. Population Line Graphs • typically have numbers on vertical axis and time on horizontal axis

  18. Biotic Potential • the maximum number of offspring that the species could produce with unlimited resources

  19. Environmental Resistance • Is the limiting factors on a population • Include food, shelter, water, predation, etc. • Puts brakes on biotic potential (B) – maximum reproductive rate

  20. Logistic Growth S shaped curves are typical of stable populations with a constant food source

  21. Logistic Growth • Eg. Wild Horses on reserve land in AB

  22. Exponential Growth • J shaped curve (initially) occurs with short-lived populations that rapidly deplete their environment

  23. Exponential Growth • Eg. Flies on a carcass

  24. Carrying Capacity • Is the number of organisms a habitat can sustain over the long term • “k”

  25. Overshoots • Result when k is greatly exceeded and the environment deteriorates

  26. Limiting Factors to Populations • Shelford’s Law of Tolerance: an organism can survive within a certain range of any abiotic factor • Greater the range, the greater the ability for the species to survive

  27. Limiting Factors on Populations • Law of the Minimum: if any one of many needed nutrients/limiting factors is reduced below the required levels, the population growth rate declines

  28. Limiting Factors • Can be density independent – those that will affect a population regardless of its size • Eg. Cold winter • Lack of water

  29. Limiting Factors • Can be density dependant – those that increase when the population size increases • Eg. Disease • Predation • Food Supply

  30. Human Population Growth Approximately 6.6 billion

  31. Taxonomy - naming • Naming system to identify different species • Used binomial nomenclature – two words

  32. Taxonomy • First word is the genus • Second is the species Equus caballus Equus burchellii

  33. Taxonomy Ursusmaritimus Castor canadensis

  34. Species - Definition • A species is a group of organisms that can interbreed under natural conditions and produce fertile offspring

  35. Levels of Classification Kingdom Animalia Phylum Chordata Class Mammalia Order Primates Family Hominidae Genus Homo Species sapiens (Kings play chess on fine grain sand)

  36. The Kingdoms 5 of them: • Monera: Bacteria and blue-green algae - sometimes subdivided into eubacteria and archaebacteria - prokaryotic (very simple) cells

  37. Protista – mostly single celled • Eukaryotic (true nucleus) • Usually aquatic

  38. Fungi – most multicellular • Heterotrophic, chitin cell walls

  39. 4. Plantae: multicellular, autotrophs

  40. 5. Animalia: multicellular, heterotrophs

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