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Population Dynamics and Growth Strategies in Isle Royale Ecosystem

Explore the dynamics of moose and wolves populations, carrying capacity, and strategies for growth in the unique ecosystem of Isle Royale. Learn how species interact and regulate their numbers, from Malthusian growth to conservation efforts.

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Population Dynamics and Growth Strategies in Isle Royale Ecosystem

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  1. Chapter 6 Population Biology

  2. 6.1 Dynamics Of Population Growth • Isle Royale • moose • wolves • carrying capacity • population balance.

  3. Species and Population • Organism • Species: genetically similar organisms that reproduce • Population: all members of a species in an area

  4. Dynamics Of Population Growth • Exponential Growth - Growth at a constant rate of increase per unit time. (Geometric) • Arithmetic Growth - Growth at a constant amount per unit time.

  5. Population Growth • Growth rate = birth – death rates • Doubling time • Rule of 70 • Tdbl = 70/ann % incr.

  6. Feedback • Positive: Change leads to more change • More Offspring = More Future Parents • Exponential Growth • Positive = Mathematically, not Necessarily in terms of Desirability • Negative: Change opposes More Change • Rate of increase lessens • More Output = Less Competition for Product = Less Profit = Less Output

  7. Nothing Can Grow Forever • One cent @ 1% interest in 1 AD: • Would now be $4.9 million • One cent @ 2% interest in 1 AD: • Would now be $1,972 trillion • 328 million tons of Gold • Total Gold Production to data: 150,000 tons • Offsetting Growth • Money: Inflation, Devaluation, Default • Population: Epidemics, Famine, War

  8. Population Oscillations and Irruptive Growth • Irruptive or Malthusian growth • Overshoot • Dieback

  9. Malthusian Growth • Malthusian Growth (Irruptive Growth) - Population explosions followed by population crashes. • Thomas Malthus concluded unchecked populations tend to grow until they reach carrying capacity and are vulnerable to crashes. • To get land's fruit in quantityTakes jolts of labour ever more,Hence food will grow like one, two, three....While numbers grow like one, two, four....

  10. Growth to a Stable Population

  11. Logistic Growth • Logistic Growth - Growth rates regulated by internal and external factors until they come into equilibrium with environmental resources. • Growth rate slows as population approaches carrying capacity. • S-Shaped curve • Environmental Resistance - Any environmental factor that reduces population growth • Environmental Resistance = Negative Feedback

  12. J and S Curves • Initial Phase (J or Exponential) • No practical limits • Growth leads to more growth • Inflection Point: Opposing Forces Kick In • Later Phase (Top of the S Curve) • Growth has Costs • Costs Inhibit Growth • Final Outcomes • Stable Limit (Best Case) • Overshoot, Crash, Oscillations • Overshoot and Catastrophic Crash (Worst Case)

  13. Growth to a Stable Population • Logistic growth • Environmental resistance (Negative Feedback)

  14. 6.2 Strategies of Population Growth • Malthusian Strategies (r-selected species) • High Reproduction rates offset high mortality • Population limited by external factors • Logistic Strategies (K-selected species) • Low reproduction rates, usually don’t reach carrying capacity • intrinsically controlled growth

  15. r-selected species • Typically Small, Short Life Span • Insects • Rodents • Marine Invertebrates • Parasites • Annual Plants • Tribbles

  16. K-selected species • Low Reproduction Rates, Usually Don’t Reach Carrying Capacity, Longer Life Span, Bigger • Wolves • Elephants • Whales • Primates

  17. Growth Factors • Natality = new individuals • often related to Environmental Conditions • Mortality • Immigration • Emigration • r = (b – d) + (i – e) • Survivorship: number that survive • Life expectancy

  18. 6.3 Regulation of Population • Density-Independent • Affect natality or mortality independently of population density • Often abiotic (weather and climate, geologic hazards, fire…)

  19. Regulation of Population • Density-Dependent (competition) • Decrease natality or Increase mortality as population increases • Interspecific(Different Species): • predator-prey, parasites, symbiosis • Example: hare - lynx • Intraspecific (Same Species) • Territoriality • Stress and crowding (e.g. mouse)

  20. 6.4 Conservation Biology • Island biogeography describes isolated populations • Conservation genetics is important in survival of endangered species • Population viability analysis calculates chances of survival • Metapopulations connected

  21. Island Biogeography • Single islands always have fewer species than similar size areas on the mainland. • Because islands are isolated, it will be harder for species to immigrate to them, lowering the rate of immigration. • Limited resources on islands mean lower carrying capacity. • Applies to isolated habitats on land, also

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