40 Questions
What is the primary reason for increased competition among organisms in a population?
Depletion of available resources
What is the term for the interaction between two different organisms in which one captures and feeds on the other?
Predation
What happens to the predator population when the prey population increases?
It increases
What is the effect of parasitism and disease on a population?
It controls the population size
What is the result of increased competition for resources in a population?
The population declines
What does the steep drop near the end of the Type I Survivorship Curve indicate?
High death rate as the organisms become older
Which type of reproduction involves producing a few offspring each year for several years?
Repeated reproduction
What is the life history of an organism a description of?
The traits that affect its schedule of reproduction and survival
What is an example of an organism that exhibits Type III Survivorship Curve?
Fishes
What is the characteristic of Type II Survivorship Curve?
Constant death rate over the organism's life span
What might happen when a population exceeds the carrying capacity of its environment?
The birth rate will decrease and the death rate will increase.
What is the carrying capacity of an environment?
The number of individuals the environment can support over a long period of time.
What happens to the population size when it exceeds the carrying capacity?
It will fluctuate above and below the carrying capacity.
What is the shape of the graph of logistic growth?
A stretched out letter 'S'.
What happens to the population growth when it reaches the carrying capacity?
It will stop.
What type of relationship is similar to parasitism?
Predator-prey
What is the main advantage of having a territory?
Unlimited use of resources without competition
What happens to a population in response to density-independent factors?
The population experiences a crash
What is an example of a density-independent factor?
Unusual weather or natural disasters
What is the effect of a parasite on its host?
The host is weakened and may eventually die
What is the consequence if all the resources are used up during reproduction?
Survival is in jeopardy
What is the term for the movement of individuals into and out of a population?
Migration
What happens to the population size if the death rate is greater than the birthrate?
It declines
What are the three factors that can greatly increase or decrease the size of a population?
Number of births, number of deaths, and number of individuals that enter or leave the population
What is the result if the birthrate is equal to the death rate in a population?
The population will remain stable
What is the primary factor affecting the birth rate in a population?
Available resources
What type of survivorship curve is characterized by a high death rate in the early stages of life?
Type III
Which of the following factors does not directly affect population growth?
Territoriality
What is the primary purpose of age-structure diagrams?
To predict the future growth of a population
What is the term for the study of the distribution of individuals among different ages in a population?
Age structure
What happens to the growth rate of a population as it reaches the carrying capacity?
It slows down
What is an assumption made by both the exponential and logistic models?
The carrying capacity is constant and does not fluctuate
What is the effect of a drought on the carrying capacity of a prairie ecosystem?
It decreases the carrying capacity
What are the exponential and logistic models used for in population study?
Useful tools to study populations
What is an example of a density-independent limiting factor?
Drought
What is the term for a factor that causes population growth to decrease?
Limiting factor
What happens to the limiting factor when the population density reaches a certain level?
It becomes a density-dependent limiting factor
What is the definition of population density?
The number of organisms per unit area
What is an example of a limiting factor that affects population growth?
Competition for resources
Why do populations have limits to their growth?
Because of the carrying capacity of the environment
Study Notes
Population Dynamics
- Population growth is controlled by two types of factors: density-dependent and density-independent factors.
- Density-dependent factors include:
- Competition for resources such as food, water, sunlight, and space
- Predation: the interaction between two different organisms where one captures and feeds on the other
- Parasitism and disease: the interaction between two organisms where one feeds on the other, often weakening the host
- Shortages of food, water, and nesting sites
- Density-dependent factors affect population growth as the population size increases, leading to competition for resources and increased predation, parasitism, and disease.
Predator-Prey Relationship
- The predator-prey relationship is a key density-dependent factor that controls population size.
- As the prey population increases, the predator population also increases, leading to a decrease in the prey population.
- As the prey population decreases, the predator population also decreases due to lack of food.
Parasitism and Disease
- Parasitism is a type of density-dependent factor where one organism feeds on another, often weakening the host.
- Disease can also affect population growth, especially as the population density increases.
Life History Traits
- Life history traits refer to the characteristics that affect an organism's schedule of reproduction and survival.
- There are two types of reproduction:
- Big-bang reproduction: an organism produces all of its offspring in a single event.
- Repeated reproduction: an organism produces a few offspring each year for several years.
- The type of reproduction an organism uses depends on its life history traits, such as the survival rate of its offspring.
Carrying Capacity
- The carrying capacity is the number of individuals the environment can support over a long period of time.
- As the population grows, it may exceed the carrying capacity, leading to a decrease in population size due to the lack of resources.
- Logistic growth is a model of population growth that takes into account the carrying capacity of the environment.
Logistic Growth
- Logistic growth is a model of population growth that slows down as the population approaches the carrying capacity.
- The graph of logistic growth looks like a stretched out "S" shape.
- When the population is at the carrying capacity, the birth rate equals the death rate, and growth stops.
Density-Independent Factors
- Density-independent factors affect all populations in similar ways, regardless of the size of the population.
- Examples of density-independent factors include:
- Unusual weather or natural disasters
- Human activities such as deforestation or damming of a river
- These factors can cause a population to crash or decline suddenly.
Population Growth Rate
- The population growth rate is the amount by which a population's size changes in a given time.
- If the birth rate is greater than the death rate, the population will increase.
- If the birth rate is equal to the death rate, the population will remain stable.
- If the death rate is greater than the birth rate, the population will decrease.
Migration
- Migration is the movement of individuals into and out of a population.
- It can affect population growth rate and size.
Age Structure
- Age structure refers to the distribution of individuals among different ages in a population.
- The age structure of a population can affect its growth rate and size.
- Age-structure diagrams are used to predict the future growth of a population.
Test your knowledge on density-dependent limiting factors that affect population growth, including competition, predation, and resource shortages. Learn how crowded populations compete for essential resources like food, water, and space.
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