1 Population Principles Chapter 3

2 Population Characteristics Population - Group of individuals of the same species inhabiting the same area simultaneously. (6.4 Billion – 2004) – Natality and Mortality  Natality - ________________________________ ________________________________  Birth Rate (Humans Born / 1,000) – Mortality - __________________________________  Death Rate (Humans Died / 1,000)

3 Figure 7.1

4 Population Characteristics Population Growth Rate - ___________________________________. Often expressed as a percentage of the total population. (Geometrically – Population)(Arithmetically – Food Supply) Survivorship Curve - Shows proportion of individuals likely to survive to each age. – High mortality in young. – Mortality equitable among age classes. – Mortality high only in old age.

5 Survivorship Curve (Fig.7.2)

6 Sex Ratio and Age Distribution Sex Ratio - Age Distribution – Sex Ratio - __________________________________ _________________________________.  Females determine the number of offspring produced in sexually reproducing populations. – Age Distribution - __________________________________ _________________________________.  Greatly influences population growth rate.

7 Age Distribution in Human Populations (Fig.7.3)

8 Population Density and Spatial Distribution Population Density - ___________________________________ ___________________________________. – High population may lead to increased competition for resources.  Dispersal - Movement of individuals from densely populated locations to new areas.  Emigration - Movement from an area.  Immigration - Movement into an area.

9 Population Growth Curve Biotic Potential - ___________________________________ ___________________________________ ___________________________________ – Generally, biotic potential is much above replacement level.  Natural tendency for increase.  All living populations follow an exponential growth curve.

10 Exponential Growth Curve Lag Phase - ___________________________________. *Currently* Exponential Growth Phase (Log Phase)- ___________________________________ ___________________________________ ________________________. *Currently* Stable Equilibrium Phase - ___________________________________ ___________________________________ ___________________________________

11 Biotic Potential (Fig.7.4)

12 Typical Population Growth Curve (Fig.7.5)

13 Carrying Capacity Carrying Capacity - ___________________________________ ___________________________________ ___________________________________.

14 Environmental Resistance Environmental Resistance - ___________________________________ ___________________________________ ___________________________________. – Four main factors:  Raw Material Availability  Energy Availability  Waste Accumulation and Disposal  Organism Interactions  Disease, Predation, and Space

15 Carrying Capacity (Fig.7.6)

16 Bacterial Growth Curve (Fig.7.7)

17 Fig. p.138

18 Reproductive Strategies and Population Fluctuations Not all species reach a stable carrying capacity. – Species can be broadly lumped into two categories:  K-strategists  r-strategists

19 K - Strategists Large organisms Long-lived Produce few offspring Provide substantial parental care Populations typically stabilize at a carrying capacity. Usually occupy relatively stable environments. Reproductive strategy is to invest in a few, quality offspring.

20 K - Strategists Controlled by density-dependent limiting factors. – Factors that become more severe as the size of the population increases.  Diseases Deer - Lions - Swans

21 r - Strategists Small organisms Short-lived Produce many offspring Little if any parental care Usually do not reach carrying capacity (boom-bust cycles). Exploit unstable environments. Reproductive strategy is to produce large numbers of offspring to overcome high mortality.

22 r - Strategists Controlled by density-independent limiting factors. – Population size is irrelevant to the limiting factor.  Weather Conditions Grasshoppers - Gypsy Moths - Mice

23 Population Cycles (Fig.7.8)

24 Human Population Growth Major reason for increasing human population growth rate is__________________________________ ___________________________________ ___________________________________ _

25 Historical Human Population Growth (Fig.7.9)

26 Doubling Time Doubling Time of a Population (years) : 70 / Population Growth Rate (%) ( 70 / 2.0% = 35 years )

27 Doubling Time for the Human Population (Fig.7.10)

28 Human Population Growth Interactions Affecting Carrying Capacity – Available Raw Materials – Available Energy – Waste Disposal – Interaction With Other Organisms

29 Social Factors Influence Human Population Humans are social animals who have freedom of choice. – People make decisions based on history, social situations, ethical and religious beliefs, and personal desires.  Biggest obstacles to controlling human population are not biological, but are the province of philosophers, theologians, politicians, and sociologists.

30 Ultimate Size Limitation If the world continues to grow at current rate, population __________________________. Human population subject to same biological constraints as other species. – Human population will ultimately reach a carrying capacity and stabilize.  Disagreement about exact size and primary limiting factors.

31 Elephant Trade

32 Snow Goose (Pg.145)