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 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. Within...Population of... an hour8 2 hours64 4 hours hours hours And within a day there will be 4.72 x ( 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

4.1 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

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

4.1 Population Dynamics 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 Life-History Pattern

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...

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