unit 9 notes

Lesson 9.1: Population Growth

How are populations described?

• A population is a group of individuals of the same species living in a geographic area.

• Ecologists use several terms to describe the health of a population

  • The geographic range is the area in which a population can be found.

  • Population density is the number of individuals of the same species in an area

    • Ex: 50 balsam poplars/acre

    • Ex: 100 people/square mile

  • Population growth is how quickly the population size is changing

What is Population Growth?

• Population growth refers to the change in the number of individuals in a population over time.

• There are two main types of population growth:

  1. Exponential growth

  2. Logistic growth

Exponential Growth

• Exponential growth occurs when a population increases at a constant rate.

  • Imagine a small group of rabbits living on an isolated island with an abundance of food and no predators.

  • In this scenario, the rabbit population would grow rapidly as each pair of rabbits reproduces multiple times a year

• As the population grows, the rate of increase also grows, leading to a steep, upward curve on a graph.

• This makes a J-Shaped curve on the graph.

Logistic Growth

• Logistic growth takes into account limiting factors such as:

  1. Availability of food

  2. Space

  3. Competition for resources

  4. Predators

• The population grows rapidly initially but slows down as it nears the carrying capacity and eventually levels off.

• This is represented by an S-Shaped curve on a graph.

What factors affect population growth?

• Populations are made of individual organisms, each with a particular lifespan.

• When discussing an individual’s life in terms of population size, there are a few terms ecologists use:

  1. Natality - The addition of new individuals

  2. Fecundity - Ability to reproduce

  3. Fertility - Number of offspring produced

  4. Morality - Death rate

  5. Life expectancy - Predicted length of survival

Summary

• A population is a group of one species found in a geographic area at a certain time.

• Depending on several factors, biological populations can grow either exponentially of logistically

Lesson 9.2: Limiting Factors to Population Growth

Why don’t populations increase indefinitely?

• The environment keeps populations from increasing forever.

  • These “limits” are called limiting factors

• Limiting factors may cause organisms to die or move out of an area.

What are limiting factors?

• Limiting factors are things in the environment that stop of slow down the growth of a population.

• Some examples of limiting factors are food, water, living space, and disease.

• There are two types of limiting factors:

  1. Density-dependent factors

  2. Density-independent factors

Density-dependent factors:

• These are environmental factors that affect a population based on its density, or the number of organisms living in a specific area.

• These factors become more influential as the population density increases

• These factors are usually biotic factors

• Example: predators, competition, disease, etc.

Density-independent factors:

• These are environmental factors that affect a population regardless of its size or density

• These factors are usually abiotic factors

• Density-independent factors can include natural disasters

• Example: Hurricanes, wildfires, and extreme temperatures

What is the carrying capacity?

• With the presence of limiting factors, the population will stabilize at a point called the carrying capacity

• Carrying capacity is the maximum number of organisms that an environment can support over a long period of time

• When a population reaches a carrying capacity, it is called a logistic growth

• Logistic growth forms S-shaped curves on a graph

• The carrying capacity is like a population equilibrium

• The population is in balance with the environment

• Like any equilibrium, the population is not perfectly constant

• It fluctuates around the carrying capacity

Summary

• Limiting factors can be density-dependent or density-independent

• These limits cause a population curve to level off at the carrying capacity, creating an “S” curve

• At this point, the population is in equilibrium

• with its environment

Lesson 9.3: Habitats, Niches, and Species Interactions

How do organisms interact with their surroundings?

• Organisms interact with their environment in various ways essential for their survival

• Three key concepts in the study of these interactions are:

  1. Habitat

  2. Niche

  3. Symbiotic Relationships

What is a habitat?

• A habitat is the specific place where an organism lives

• Habitat provides the necessary resources for the organism to survive

• These resources include:

  1. Food

  2. Water

  3. Shelter

  4. Space

Types of habitats

• Difference organisms have different habitat requirements.

For instance:

1. A frogs habitat could be a pond where it finds food, protection, and a place to breed

2. While a cactus thrives in hot and dry desert environments.

• Since different organisms have different habitat requirements, there are several types of habitats.

• Some of them are:

  1. Aquatic

  2. Forest

  3. Freshwater

  4. Grassland

  5. Terrestrial

  6. Polar

  7. Boreal

What is a Niche?

• A niche is the unique role a species plays in its environment

• It includes:

  1. The way an organism obtains its food

  2. The type of shelter it requires

  3. How it reproduces

• Think of a niche as a unique job that each species has in the ecosystem.

• For example, the niche of a squirrel may involve:

  1. Eating nuts and seeds

  2. Living in trees

  3. Competing with other squirrels for food and territory

Types of Niches

• There are two main types of niches: fundamental and realized.

• A fundamental niche is the role an organism can occupy without competition.

• A realized niche is the smaller niche an organism occupies because of competition.

What is tolerance?

• Tolerance is the ability of an organism to survive in changing condition within their niches

• These changing conditions may include lack of prey, drought, extreme temperatures, etc.

• There are two types of organisms based on tolerance.

  1. Specialists - organisms that have limited tolerance and can only withstand small changes in their niche

  2. Generalists - organisms that adapt easily to changes in their niche due to large ranges of tolerance

     • Raccoons can live in many different habitats: Generalist

     • The giant panda only eats bamboo: Specialist

Symbiotic Relationships

• Symbiotic relationships are interactions between different species that live closely together

• These relationships can be beneficial, harmful, neutral.

• There are three main types of symbiotic relationships:

  1. Mutualism

  2. Commenalism

  3. Parasitism

Mutualism

• In mutualism, both species benefit from the relationship

• This relationship is +/+

Examples:

1. Bees and Flowers: Bees pollinating flowers and receiving nectar in return.

2. Oxpeckers and Rhinos: Oxpeckers eat parasites off rhinos, maintaining their health and gaining food.

3. Clownfish and Sea Anemones: Clownfish find shelter in sea anemones, defending them from threats and providing them nutrients.

Commensalism

• In commensalism one species benefits while the other is not affected

• This relationship is +/0

Examples:

1. Remoras hitch rides on sharks without bothering them, getting free transportation and food scraps.

2. Barnacles stick to whales and get food and transportation, but don’t bother the whale

3. Birds make nests in trees for shelter, which doesn’t harm the tree

Parasitism

• In parasitism, one species benefits at the expense of the other

• This relationship is +/-

Examples:

1. Ticks feed on the blood of animals, weakening them and sometimes spreading diseases

2. Fleas bite pets and humans causing itching an discomfort while feeding on their blood

3. Tapeworms live in the intestines of animals, stealing nutrients and causing sickness

Predation

• In predation, one organism is harmed and one benefits, but this interaction is short-lived

  Examples:

1. A lion hunts and eats a gazelle for its meal'

2. A hawk swoops down to catch and eat a mouse in a field

3. A snake coils around a mouse, squeezing it to death before swallowing it whole

Competition

• In competition both organisms are harmed

• This relationship is -/-

Examples:

1. Two squirrels race to gather nuts from the same tree, competing for food

2. Lions and hyenas compete for the same prey such as zebras or wildebeests

3. Birds in a forest compete for nesting sites and food sources like berries and insects

Amensalism

• In amensalism, one organism is unaffected while the other is negatively impacted

• This relationship is 0/-

Examples:

1. A large tree casts shade on smaller planets beneath it, inhibiting their growth without being affected itself

2. Elephants trample grass and vegetation as they move, damaging plants underfoot without being impacted

Neutralism

• In neutralism, organisms coexist without affecting each other

• They may share the same habitat but have no direct interaction

• This relationship is 0/0

Summary

• Organisms have roles in their environments called niches

• The tolerance of an organism is its ability to adapt to changes in its niche

• Organisms can also interact with each other in relationships that are beneficial, neutral, or harmful.

Lesson 9.4: Biodiversity

What is Biodiversity?

• Biodiversity is the variety of life forms found in a particular habitat or ecosystem

• This includes all living organisms, from plants and animals to fungi and microorganisms

• Biodiversity plays a crucial role in maintaining the balance of nature and ensuring the health of our planet

Types of Biodiversity

1. Genetic diversity

2. Species diversity

3. Ecosystem diversity

• The 3 types of biodiversity influence each other.

Genetic Diversity

• Genetic diversity is the variety of genes within a species

• A high level of genetic diversity allows species to adapt to changing environments and resist diseases

Species Diversity

• Species diversity is the variety of different species within an ecosystem

• A diverse range of species helps to maintain ecosystem stability and resilience

Ecosystem Diversity

• Ecosystem diversity is the variety of different habitats and ecosystems within a region

• Each ecosystem has its own unique set of plants, animals, and environmental conditions

Importance of Biodiversity

• Biodiversity is important for several reasons:

  1. Ecological balance: Different species depend on each other for food, shelter, and other resources

  2. Medicinal resources: many lifesaving drugs and treatments come from plants and animals found in diverse ecosystems

  3. Economic value: Biodiversity supports industries such as agriculture, fishing, and ecotourism

Adaptation and Resilience

• Resilience is the ability of an ecosystem to withstand and recover from disturbances such as natural disasters or human activities

• Ecosystems exhibit resilience through adaptation, where they adjust to changing conditions to survive and thrive

• For instance, after a forest fire, certain plants species may quickly recolonize the area, showcasing resilience in action.

Protecting and Conserving Biodiversity

• It is essentially to protect and conserve biodiversity for future generations.

• Individuals can help by:

1. Reducing Pollution:

   • Pollution harms plants, animals, and ecosystems

   • By reducing our waste and carbon footprint, we can protect biodiversity.

2. Preserving Habitats:

   • Protecting natural habitats such as forests, wetlands, and coral reefs helps to safeguard the plants and animals that live there.

3. Supporting Conservation Efforts

   • Organizations and governments work to preserve biodiversity through:

     • Sustainable resource management

     • Habitat resoration

     • Wildlife protection

Summary

• Biodiversity is the variety of living things

• There are 3 main types of biodiversity: Species, genetic, & ecological

• Ecosystems with high biodiversity are more resilient to natural and human made changes

• We can protect and conserve biodiversity by reducing pollution, preserving habitats, and supporting conservation efforts

Lesson 9.5: Ecological Succession

What is Ecological Succession?

• Ecological succession is the gradual process of change and development in an ecosystem over time

• There are two main types of ecological succession:

  1. Primary succession

  2. Secondary succession

Primary Succession

• Primary succession occurs in an area that has never been colonized before

• It occurs at places such as:

  1. Volcanic islands

  2. Glacial Moraines

  3. Sand dunes

  4. Lava flows

  5. Exposed rock surfaces

• Pioneer species establish themselves first in primary succession.

Pioneer Species

• Pioneer species are the first organisms to colonize the barren environment in primary succession

• These pioneer species, like lichens and mosses, are able to grow in harsh conditions

• They break down rocks, creating soil for other plants to grow.

Landscape Transformation

• Over time, as soil develops, larger plants, shrubs, and eventually trees can take root

• This gradual establishment of vegetation transforms the landscape and attracts new animal species to the area

Secondary Succession

• Secondary succession occurs in areas where there was once an ecosystem that has been disturbed or disrupted

• Places where secondary succession occur:

  1. Abandoned agricultural fields

  2. Forests after logging

  3. Areas after logging or disasters

  4. Abandoned urban areas

• Unlike primary succession, secondary succession occurs in areas that already have existing soil.

• The process begins with the growth of fast growing and hardy plant species that can quickly repopulate the area

• These plants help stabilize the soil and create more favorable conditions for other plant species to colonize the area

• Over time, the ecosystem begins to recover and may eventually reach a climax community

Climax Communities

• Climax communities represent the stable endpoint of ecological succession in a particular environment

• These communities are characterized by a relatively stable and diverse array of plant and animal

• Climax communities typically have reached a state of dynamic equilibrium

• Species composition and environmental factors remain relatively constant over time, barring major disturbances

Keystone species

• Keystone species are animals or plants in an ecosystem that have a big impact.

• They help keep the ecosystem balanced and healthy

• They do important jobs like:

  1. Controlling the populations of other species

  2. Creating homes for lots of different animals

Summary

• Ecological succession is the process of change within an ecosystem

• Primary succession occurs in areas that have not been previously occupied

• Secondary succession occurs when communities re-grow in areas that have experienced a disturbance

Lesson 9.6: Sustainable Use of Resources

Sustainable Use of Resources

• We rely on many different types of resources to meet our needs

• These resources can be grouped into two main categories:

  1. Renewable resources

  2. Non-Renewable resources

Renewable Resources

• Renewable resources are those that are naturally replenished over a short period of time

• Examples include:

  1. Sunlight

  2. Wind

  3. Water

  4. Forests

• These resources can be used with the fear of depletion because they are constantly renewed by nature.

Non-renewable Resources

• Non-renewable resources are finite and will eventually run out if not used wisely

• Examples include:

  1. Fossil fuels like coal, oil, and natural gas

  2. Nuclear energy

  3. Mineral deposits

• Once these resources are depleted, they cannot be replaced in our lifetime

Ecological Footprint

• An ecological footprint is a measure of the demands made by one person or group on global natural resources

• An ecological footprint includes:

  1. The materials and resources consumed

  2. The resources need to dispose of the waste produced

Reducing Your Ecological Footprint

• To reduce your ecological footprint, you can take simple actions like:

  1. Walking, biking, or taking public transportation instead of driving everywhere

  2. Turning off lights and unplugging electronics when not in use

  3. Eating less meat and supporting local farmers

  4. Using a reusable water bottle and shopping with reusable bags

What is Sustainable Use of Resources

• Sustainable use of resources means using them in a way that meets present needs without compromising the ability of future generations to meet their own needs

• This involves

  1. Using resources wisely

  2. Reducing waste

  3. Promoting conservation efforts

How to Use Resources Sustainably

1. Reduce, reuse, recycle: Use less stuff, reuse what you can, and recyle to make old things new again.

2. Choose renewable energy: Go for solar or wind power instead of fossil fuels to help the environment.

3. Conserve water: Use water wisely, fix leaks, and use water-saving gadgets to save water

4. Support sustainable agriculture: Buy local and organic good, and support farmers who farm in eco-friendly wats.

5. Protect biodiversity: Save natural places, plant local plants, and avoid harming animals and plants

What happens if we don’t use resources sustainably

• Impacts of excessive consumption include:

  1. Climate change

  2. Declining ecosystem health and biodiversity

  3. Pollution

Summary

• Your ecological footprint includes the renewable and non-renewable resources used and waste produced.

• Reducing our global ecological footprint by living sustainably will allow resources to be available for future generations.