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Chapter 4

Chapter 4. Population Biology. 4.1 Population Dynamics. Exponential Growth = J-shaped curve As a population gets larger, it grows at a faster rate Rapid growth more babies = more babies. sparkleberrysprings.com/.../g/curveexp.png. 4.1 Population Dynamics.

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Chapter 4

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  1. Chapter 4 Population Biology

  2. 4.1 Population Dynamics • Exponential Growth = J-shaped curve • As a population gets larger, it grows at a faster rate • Rapid growth more babies = more babies sparkleberrysprings.com/.../g/curveexp.png

  3. 4.1 Population Dynamics Say that it takes 20 minutes for a bacterium to replicate. So after 20mins the one cell has become 2, and after another 20 minutes those two have both replicated to 4 and so on. And within a day there will be 4.72 x 1021 (4 722 366 482 896 650 000 000 000 or 472 million million million) bacteria cells. And assuming the mass of each bacterium is 1 picogram, by the end of 2 days the bacteria would be over 3 times the mass of the earth

  4. 4.1 Population Dynamics • Limits to growth- • Eventually limiting factors will take effect • availability of nutrients, the number of predators, and the accumulation of waste materials • Population stabilizes in an S-shaped curve www.maf.govt.nz/.../emerging-weeds/fig4.gif

  5. 4.1 Population Dynamics • Carrying Capacity - # of one type of organism that an area can support • If you overshoot the CC then LF take effect. • Deaths > Births to make population fall below CC www.algebralab.org/img/cb07ae0c-5106-416c-840...

  6. Rapid L-HP: increases and decreases rapidly Unpredictable enviro. Small body size Mature rapidly Reproduce early Short life span Ex. Mosquito, bacteria Slow L-HP: maintains at or near carrying capacity Stable environments Large species Longer maturation Reproduce later Long life span Humans, elephants, whales 4.1 Population Dynamics • Life-History Pattern

  7. 4.1 Population Dynamics

  8. 4.1 Population Dynamics

  9. 4.1 Population Dynamics • Limits on Population Growth • Density – Dependent • Disease/parasites • Competition • Predators • Food/water • Density – Independent • Weather/climate • Natural disasters • Chemical pesticides animals.nationalgeographic.com/staticfiles/NG... http://www.wpclipart.com/weather/scenes/forest_fire.png

  10. 4.1 Population Dynamics • Crowding and Stress can be LF…causes • Aggression • Decreased fertility • Decrease in parental care • Decrease resistance to disease pawofjustice.org/uploads/kingsnake2.jpg

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