Modeling Human Population Growth Chapter 7 Modeling Human Population Growth

Essential Vocabulary Model Physical model Conceptual model Mathematical model Computer model Birth rate Death rate Immigration Emigration Ecology Population dynamics Fertility Rate Carrying capacity Population density Growth Rate Predator-Prey Relationship

Essential Vocabulary Population curve Linear growth Exponential growth J-curve S-curve Population crash

Activity 7.1: What is a model? A representation of a system or its components Example: macaroni noodles represented otters in the population estimation lab

Types of models: Physical Model Conceptual Model Mathematical Model Computer Model

Types of models: Physical Model 3-D representation of a system. Shows physical relationships between components of the system. EX: Model car, or model of an atom

Physical Model:

Physical Model: B-52 Model Plane

Types of models: Conceptual Model- A diagram or pictorial representation of the components of a system EX: Food webs Energy flow diagram

Conceptual Model

Conceptual models Periodic table Maps Family trees

Types of models: Mathematical Model- A Quantitative description of the relationship between multiple variables Usually expressed as an equation EX: Final Population = [(birth rate – death rate) x initial pop.] + initial pop.

Mathematical models

Types of models: Computer Model A computer-generated representation of a system. Rapid calculations Rapid manipulation of mathematical variables. A form of mathematical model EX: World population projections Weather forecasting

Activity 7.3: Changing Populations Ecology Branch of life science Study of interactions among organisms and their surroundings.

Changing Populations Population Dynamics Study of factors that cause population change over time. Factors include: Birth Rate / Death Rate Immigration / Emigration

Changing Populations Birth rate Death rate # of births / year / 1,000 organisms Death rate # of deaths / year / 1,000 organisms

Changing Populations U.S. Statistics: Birth rate = 13.9 Death rate = 8.2 In 1900, the death rate was 17.2 ! Why has the death rate decreased dramatically since 1900?

Why has the U.S. death rate decreased significantly since 1900? Science & Technology: Medical equipment Vaccines, Antibiotics Water treatment facilities Sewage/ waste treatment facilities

Changing Populations Fertility Rate RATIO btwn births & adult females in a specific population at a particular time.

Changing Populations Predator-Prey Relationship A relationship between two species of organisms in which one is a food source for the other.

Changing Populations Immigration Emigration Movement of organisms INTO an ecosystem Emigration Movement of organisms OUT of an ecosystem

Changing Populations Growth Rate Relative change in the value of a variable. Final Population = POPinitial + Births + Immigration - Deaths - Emigration Growth Rate = (POPfinal - POPinitial ) / POPInitial

Changing Populations Carrying Capacity The maximum population an ecosystem can support. carrying capacity factors: Availability of: living space, food, climate

Changing Populations Population density The total number of organisms of a species in the same ecosystem at the same time.

How is population density calculated? Pop density = # organisms / total area EX: # of people / square mile # of organisms / km2

Which regions of the world have the highest population density? Regions with highest population- do not always have the highest population density. WHY? LAND AREA is an important variable in calculating population densities

Nevada Population Density

Las Vegas Valley Population Growth

Population Density China 1.3 Billion People 136 people / sq mile Japan 28 Million people 338 people / sq mile

Ch 8: Population Dynamics Population curves can help predict future population changes Conditions that affect population growth: carrying capacity factors: Availability of: living space, food, climate birth rate, death rate, migration

Graphing Population Curves: plot all data points and connect them. Do NOT make a line of best fit. line of best fit shows an “AVERAGE” of data points, not a linear growth pattern.

Population Curves

What do population graphs look like? 8.1 What do population graphs look like? Negative growth rate – the population is decreasing Positive growth rate – the population is increasing Linear Exponential Population size stays the same

Linear Curves Steady population increase by the same amount over regular time intervals (years) y = 2x y is population size x is time

Exponential Population Growth J-curve Rapid Growth rate y=2x

Exponential Growth: Exponential population curves cannot continue upward indefinitely Exponential population growth eventually slows: usually resulting in the formation of an: S curve

S - Curve exponential (rapid) growth followed by a growth slow down Eventual leveling off (flattening) Usually when the population reaches its carrying capacity

Population CRASH Rapid Decline in Population:

Causes of Population Crash: Communicable, Infectious Disease Catastrophic Events hurricane, earthquake, tsunami, volcano Loss of productivity in first trophic level loss of topsoil in an agricultural area