populations n.
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Populations - PowerPoint PPT Presentation

keegan
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Populations

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  1. Populations

  2. Populations • Population - a group of organisms of the same species which have the potential to interbreed – or a population is a group of organisms of the same species occupying a particular place at a particular time • Populations have a number of properties which are not possessed by individual organisms - this is because a population is the sum of many organisms interacting

  3. Starling Murmuration http://vimeo.com/31158841

  4. Density and Distribution

  5. Prairie Dog Distributions

  6. Properties dealing with changes in population size • Natality - may think of this as births, but includes more than just birth - hatching, germination, fission • Natality includes idea of fecundity - number of offspring produced per unit time - we are most concerned with realized fecundity - actual number of survivors • Mortality - death rate - its converse is survivorship - mortality looks at how many die per unit time, survivorship at how many don't die per unit time • Longevity examines life-span of individuals - again we are most interested in realized longevity, not potential longevity • Immigration - individuals moving into a population • Emigration - individuals leaving a population

  7. What is an individual? • unitary organism - individuals are highly determinate in form and while growing pass through predictable (innately determined) sequences of life history stages • modular organisms - zygote develops into unit, or module, which produces more modules thus producing an organism with a variable number of modules, whose development is unpredictable and strongly influenced by environmental factors

  8. A classic unitary organism

  9. A classic modular organism Bryozoan colony

  10. More classic modular organisms

  11. Genets and Ramets • ramet - a module with the potential for a separate existence • genet - the "genetic individual"; the collection of all modules derived from a single zygote

  12. A single Aspen clone

  13. Posidonia oceanica – Neptune grass

  14. Sampling to collect population data Census - most basic sampling - count and determine age of all individuals in population, count again later Several ways to subsample and estimate population size: 1. Determine total area in which population occurs, count all individuals in small plots, multiply average number in plots to get total, repeat at later dates - works best for sessile organisms 2. Mark-recapture methods 3. Catch per unit effort 4. Miscellaneous methods – traps, counts of fecal pellets, counts of vocalizations, feeding damage on plants, radar counts, roadside sightings, fur or pelt records, roadkill

  15. Quadrat Sampling

  16. Mark recapture of Cicadas

  17. Catch per unit effort – Pacific Threadfin

  18. Beetles feeding on Viburnum

  19. Beetle damage on Viburnum

  20. Bird migration data – typical altitude – from radar

  21. Bird migration radar map

  22. Skylark

  23. Metapopulations • A metapopulation is a series of small, separate populations united together by dispersal

  24. Metapopulation Dynamics

  25. Metapopulations of Bay Checkerspot Butterfly

  26. Bay Checkerspot Jasper Ridge

  27. Aphids and Epilobium

  28. Habitat fragmentation in Amazonia

  29. Demography

  30. Demography • Demography is the study of processes that influence population size - it is the way we study changes brought about by births, deaths and dispersal For Northwest Montana, Greater Yellowstone, Central Idaho

  31. The Fundamental Equation of Ecology – Harper 1977 Δ N = B – D + I – E Change in Number = Births – Deaths + Immigration - Emigration John L. Harper – 1925-2009

  32. Rearrange Fundamental Equation Δ N = B – D + I – E Nfuture = Nnow + B – D + I – E

  33. Common Field Grasshopper