6Density-dependent limiting factors a) Affect large, dense populations more than smaller, less- crowded populations“Depends” on “density”
7Density-dependent limiting factors Predation:Fig. 4.5Wolves & Moose on Isle Royale
8The amount of food for the mouse Disease among the wolf population Isle RoyaleIn addition to the predator/prey relationship, the moose and wolf population were affected by:The amount of food for the mouseDisease among the wolf population
20If natality is 10, mortality is 6, immigration is 3, and emigration is 2…… What is the net effect on the population size?If the original population consisted of 10 individuals, what is the new population size?
21Population Growth Rate If birth rate > death rateThe population will…..If birth rate < death rateThe population will….
22Exponential Growth (J–shaped curve) If ideal conditions (have everything!) continue, the population will continue to grow rapidlyDoubling and re-doubling1, 2, 3, 8, 16, 32, 64, 128……..Does NOT last long in nature – WHY?
23Exponential Growth (J–shaped curve) d) This is current human population growth worldwideHow long can it last?Discusse) Draw graph*Industrial revolution
24Boom and BustAs ideal conditions continue, population grows exponentially until it reaches a “peak” size (boom) and then crashes (bust)Ex: Rabbit populationDraw graphs
27Logistic Growth (S-shaped curve) a) Exponential growth at first, eventually the population size levels off as the growth rate slows down b) Carrying capacity: Largest number of individuals that the environment can support
28Logistic Growth (S-shaped curve) Draw graphThings that prevent the population from getting too big:Lack of food or waterHome/shelter availability
29Reproductive Patterns r-strategy: rate strategyGenerally are smallShort life spansProduce many offspringrat, fruit fly, locusts (Fig. 4.9)
30Reproductive Patterns k-strategy: carrying capacity strategyLarger organisms, long life spanProduces few offspring –better chance of survivalTake care of the offspring, usually for a long timeKangaroo, elephant
31DemographyThe study of human population size, density, distribution, movement, and birth and death rates
32Demographic Transition A change in a population from high birth and death rates to low birth and death rates(Read pg 102)