Name: _____________________ Class: ___
Biology-Harlacher
Notes-Chapter 4 (Population Biology)
Population Dynamics
________________________ is the study of change in populations including
growth, decline, births, deaths, internal interactions, and external interactions.
This can be used for __________________, even ____________.
Principles of Population Growth
What is a population?
_______________________________________
Populations ________________________at a steady pace unless they run out of
food, water, shelter, or space or are attacked by diseases or predators.
The Speed of Population Growth
Populations undergo ________________________, not _____________________.
This results in a ________________________ when plotted on a graph.
The population begins small, and reproduces slowly but as it grows, grows in leaps
and bounds.
Exponential Growth
If a population undergoes exponential growth it is ___________________________.
Limiting Factors
A _________________is anything that limits the exponential growth of a population.
This can include:
The availability of food, water, space, or shelter.
Disease
Competition
Predation
Catastrophic events
If a population is limited in some way, it becomes an _________________________.
It grows exponentially until it is limited and then it remains ____________________.
Carrying Capacity
________________________ is the number of individuals in a population that an
environment can support indefinitely.
When a population develops in an area it begins exponential growth until it
_______________ the carrying capacity.
It is then limited. Some organisms will not be able to survive and the population will
_______________ to below the carrying capacity.
Over time the population size will __________ above and below the carrying capacity.
Reproduction Patterns
Why don’t populations reach their carrying capacity and remain stable?
To explore this we look at an organism’s ________________________ or
________________________.
____________ have a very short life span and reproduce rapidly and produce many
offspring.
____________ have a long life span, but take years to be able to reproduce and only
produce a limited number of offspring.
Rapid Life-History Patterns
Organisms with ____________________________________ come from unstable or
changing environments.
They tend to be smaller, mature rapidly, reproduce early and in large numbers, and
have a short life span.
This allows them to better survive and reproduce in their environment.
Their populations ____________________ depending on environmental conditions.
Slow Life-History Patterns
Organisms with ____________________________________ come from stable or
relatively changing environments.
They tend to be larger, mature more slowly, reproduce later and in smaller numbers,
but have a long life span.
This allows them to better survive and reproduce in their environment.
Their populations ____________________________________________________.
Density Factors
____________ is the number or amount of something in a given space.
____________ is how something is spread out in that area.
______ is the number of individuals in a population
The density and dispersal of organisms in an area greatly affects their population size
and ability to survive.
Dispersal Patterns
____________
____________
____________
Reasons for uniform dispersal:
_____________________________________
Reasons for clumped dispersal:
_____________________________________
Reasons for random dispersal:
_____________________________________
Density-Dependent Factors
These factors ____________________________________as population increases.
Disease, competition, predators, parasites, water, and food.
Density-Independent Factors
These factors affect populations __________________ of size.
Usually _________________ such as:
Volcanic eruptions
Temperature
Storms
Precipitation (floods or droughts)
Pesticides or Poisons
Catastrophic Events and Habitat Disruptions
Population Interactions
Some interactions between populations and individuals can affect population size:
____________
_____________________ (Different Populations)
_____________________ (Same population)
__________________
Predation
____________ can keep a population limited and contained (a weasel eating chickens)
or it can drastically affect a population (locusts eating almost all of a field).
Usually predator and prey population sizes _________ each other and are ________.
This is a density-dependent factor.
Interspecific Competition
This is when members of ______________________________________________
compete for the same resources.
A large tree may block the sunlight from a smaller tree.
Lions, cheetahs, and hyenas will all compete for the same zebra (alive or dead).
Grey squirrels and red squirrels compete for the acorns of the oak trees in your yard.
This is a ____________________________________.
Intraspecific Competition
This is when members of the __________________compete for the same resources.
Two lion prides fight for a particular territory.
Two male deer fight to be able to mate with a female.
This is a ____________________________________.
Crowding/Stress
When population of certain species become crowded, they may show signs or
symptoms of ____________.
These can include:
Increased aggression
Decrease in parental care
Decreased fertility
Decreased resistance to disease
These are all ____________ and can become ____________________________.
Demography
Demography is the study of the human population and its’:
______
____________
__________________
__________________
______________
______________
____________
Human and World Population
Human population growth has occurred at an ___________________________since
about 1800. Before that it was relatively stable.
This is mostly due to new technology, hygiene, and medicine.
__________________ allowed food to be stored safely for longer and new
transportation allowed it to be sent to farther away.
Better hygiene and medicine allowed people to live longer and more safely.
Factors Affecting Human Population Growth
Humans are affected differently than other organisms because we can change our
environment and surroundings more easily.
We have ______ against and eliminated many diseases.
We have ____________ more efficient methods of growing food.
There is lower _______________________and better medical care than in past times.
Many have easy access to clean water
We have improved our ______________ and ____________.
Calculating Growth Rate
__________________-the number of live births per 1000 population in a given year.
__________________-the number of deaths per 1000 population in a given year.
__________________-the movement of individuals between populations
__________________-when individuals enter a population
__________________-when individuals leave a population
Birthrate = ____
Death rate = ____
Immigration = __
Emigration = __
Population Growth Rate = _____
(BR + I) – (DR + E) =PGR
However because numbers for immigration and emigration are often not accurate
we simplify it to:
If the __________________ and the __________________are equal, then the
population growth rate will be ________.
This doesn’t mean that the population is not changing. It just means that the same
number of individuals are entering the population (births and immigration) as are
leaving the population (deaths and emigration
If the PGR is __________________, then more individuals are ____________ than
leaving the population.
If the PGR is __________________, then more individuals are ____________ than
entering the population.
What does a PGR of 1.2 mean? ________________________________
What does a PGR of 0.1 mean? ________________________________
What does a PGR of -0.08 mean? ________________________________
Doubling Time
________________ is the amount of time needed for a population to double in time.
It will depend on the current population size and growth rate.
A country with a quick doubling time is often referred to as a ___________________
A country with a slow doubling time is often referred to as a ___________________
Age Structure
_______________ is the proportion of the population that are in different age levels.
At this point, they have been constructed for almost every country of the world.
It will tell you an ________________________ of males and females as well as ages.
Types of Age Structures
Rapidly growing countries (high PGR) will have a ____________since most of the
population is _________.
Countries that have a PGR around 0 will be ________ in each age group because
there is not much growth.
Countries in population decline will have a ________________________ and it will
thin towards the bottom since there are more ______________.
Ecology and Growth
Different governments have different ____________ towards their citizens.
Some only provide the most basic needs.
Some want to maintain the quality of living of their citizens.
Some want to improve the quality of living of their citizens.
This can come down to what resources are available for the population.
If a population grows too rapidly for the ________________________ it surpasses
its’ carrying capacity.
This means that not everyone will be provided for.
This can lead to stress which can result in conflict, riots, war, a higher crime rate,
or other ____________________.