TWO TYPES OF POPULATION GROWTH IN ECOSYSTEMS EXPONENTIAL

TWO TYPES OF POPULATION GROWTH IN ECOSYSTEMS: EXPONENTIAL GROWTH LOGISTICAL GROWTH Which represents the human population? ?

Malthusian Growth (Irruptive Growth) Population explosions followed by population crashes. § Malthus concluded human populations tend to grow until they exhaust their resources and then crash. POPULATION CHANGE: N = (birth + immigration) – (death + emigration) When these factors balance out it is known as ZERO POPULATION GROWTH (ZPG)

I heart musti Population Growth • 1. Ability to expand into diverse habitats and climates • 2. Agriculuture • 3. sanitations systems, antibiotics, vaccines

FACTORS AFFECTING HUMAN POPULATION SIZE Crude Birth Rate = # of live births per 1000 Crude Death Rate = # of deaths per 1000 95% of daily population growth occurs in developing countries Global Growth Rate = 1. 3% (equivalent to adding another USA every 3. 6 years) Top 10 Most Populous China = 1. 5 billion ~40% India = over 1 billion USA = ~300 million 5% Indonesia, Brazil, Pakistan, Russia, Bangladesh, Japan, Nigeria

FACTORS THAT INDICATE POPULATION GROWTH: Replacement Level Fertility = # a couple must bear to replace themselves Developed = 2. 1 Developing = 2. 5 Total Fertility Rate (TFR) – average # of children a woman will have during her child bearing years (15 -49) Developed = 1. 6 (2. 5 in 1950) Developing = 3. 1 (6. 5 in 1950) Even if each of today’s couples had an average of 2. 1 children, the population would continue to grow for 50+ years because of: population momentum

The growth rate for the US in the year 2000 was close to 1% (~40 -50% of the growth is due to immigration into the country) CURRENT POPULATION = over 300 million The US will double in size in the next 70 years. It is currently growing faster than any other developed nation. The TFR (total fertility rate) as a whole for the US is at replacement level = 2. 1 The period following WWII saw a spike in birth rate known as the baby boom. United States Population Statistics

POPULATION AGE STUCTURES: Rapidly expanding populations: Have large number of pre-reproductive individuals and thus have population momentum.

AGE STRUCTURES: examples

q Pre-Industrial = high BR + high DR (low pop growth) q Transition = high BR + low DR (rapid pop growth) q Industrialized = low BR + low DR (low pop growth)1) Access to birth control 2) decline in infant mortality 3) Increased education & jobs for women

What Affects Birth Rate & Fertility? • Education, employment, & status of and for women • Infant mortality rate • Availability of contraceptives • Religious & social beliefs • The importance of children as a part of the work force. • Urbanization – tend to have fewer children • Cost of raising and educating children. • Average of marriage.

What Factor’s Affect Death Rates? DECREASES DEATH RATE: 1) Increased Food Supply & Distribution 2) Better Nutrition 3) Medical improvements/Technology – vaccines antibiotics Global Life Expectancy has &increased from 48 to 66 in the last 55 years. 4) Safe Water Supplies (decreases spread of disease) 5) Increase in sanitation and personal hygiene Indicators of overall health of a country: Life Expectancy – average # of years a newborn infant can expect to live & Infant Mortality - #infant of infants outindicates of 1000 good who will die within A low mortality nutrition & safeone year drinking water (low rate of disease)