Select your language

Suggested languages for you:
Log In Start studying!
StudySmarter - The all-in-one study app.
4.8 • +11k Ratings
More than 3 Million Downloads
Free
|
|

All-in-one learning app

  • Flashcards
  • NotesNotes
  • ExplanationsExplanations
  • Study Planner
  • Textbook solutions
Start studying

Ecology

Save Save
Print Print
Edit Edit
Sign up to use all features for free. Sign up now

Want to get better grades?

Nope, I’m not ready yet

Get free, full access to:

  • Flashcards
  • Notes
  • Explanations
  • Study Planner
  • Textbook solutions
Ecology

Have you ever stepped into your garden and noticed the incredible display of nature, from ladybirds crawling on leaves to worms burrowing in the soil, to bees buzzing around flowers? Or have you been to the beach and seen the variety of marine organisms that get washed ashore, like crabs, barnacles, or seaweed?

If yes, then you have witnessed ecology in action! Ecology refers to how living organisms interact with each other and their physical environment.

Ecology definition

Ecology is the branch of biology that helps us to understand everything from the organisms around us to the environment that they live in. It also helps us to understand how these different organisms interact with each other, and with the environment around them.

People who study and research ecology are called ecologists. Ecologists seek to explain:

  • How living organisms interact with one another.

  • How living organisms interact with their habitats.

  • How energy is transferred between living organisms.

  • The distribution (spread) of living organisms in the world.

Ecology system

Ecological relationship depend on the dynamics between abiotic and biotic factors.

Biotic factors are living things within an ecosystem. They also included organisms that were once-living but now are not. Examples of biotic factors include animals, fungi, plants, bacteria and more.

Abiotic factors are factors that are not living, or have never been living. This includes weather conditions, such as temperature, humidity, wind speed and light intensity, amongst many other factors.

A major part of ecology is to understand how and why living organisms live in the places they do, or why their population increases or decreases. These patterns are influenced by these biotic factors and abiotic factors. Biotic and abiotic factors both play crucial roles in the functioning of an ecosystem, any changes to the biotic factors or abiotic factors in an area will change the dynamic within an ecosystem.

To understand what biotic and abiotic factors are, let’s consider woodlice as an example.

Woodlice prefer damp environments, such as moist soils. This is why you may find them crawling on your soil in your garden. Soil moisture is an example of an abiotic factor; a non-living component of the environment that affects how living organisms are distributed (spread). In terms of feeding, woodlice prefer to eat rotting plants. This is why woodlice will be happy to stay in your garden since they have a large supply of rotting plants to eat! Plants are an example of a biotic factor; a living component of the environment that affects how living organisms are distributed.

Ecological niche

Ecological niche is the role that an organism plays within a community. This includes all biotic and abiotic factors that influence this organism. When talking about the ecological niche of an organism, we have to consider factors such as the abiotic factors that an organism can tolerate, such as weather conditions, humidity and more. We also have to consider the resources that these organisms require. This could include water required by the organism, and food. Finally, we have to consider how this organism interacts with other organisms. This includes whether it competes with other organisms for resources, whether it acts as a pest or whether it is involved in a predator-prey, or mutualistic relationship.

Competition can be interspecific or infraspecific. Interspecific competition refers to a situation where organisms have to compete with organisms of another species for resources. Intraspecific competition refers to a situation where organisms have to compete with organisms from their own species for resources.

There are many different types of relationships behind organisms that we have to consider when thinking about an ecological niche. +/- relationships involve relationships where one organism benefits, whilst the other suffers. Examples of this would be predator/prey interactions or competition. Another type of relationship is a +/+ relationship, which is a relationship where both organisms benefit. An example of this is the relationship between the spider crab and algae. Spider crabs live in shallow areas of the ocean floor, while greenish-brown algae live on the crabs' backs, camouflaging the crabs from predators by allowing them to blend into the ocean floor. By helping the crabs, the algae get a place to live.

Parasites are organisms that have a +/- relationship with another organism. They survive or benefit from the other organism, causing it damage over time. The organism hosting the pest receives no benefit and is damaged over time, potentially even leading to death.

The difference between a parasite and a predator is the time over which they cause damage. A parasite tends to have a longer effect on the host that it attacks, draining resources and causing damage over time. A predator, however, hunts and kills prey in a shorter period of time. Both of these interactions are +/- relationships.

Population ecology

Ecologists study ecology at five levels, increasing from small to large (see figure on levels of ecology). These are listed below:

OrganismsAn organism is any organic, living system that functions as an individual entity.ecologists studying ecology at the organism level are mainly interested in how living organisms are adapted to live in their environment, or habitat
PopulationA population is a group of living organisms of the same species that live together in the same area. Ecologists who study populations are interested in the number of individuals in populations, and how and why the size of populations change over time.
CommunityA biological community involves populations of different species living in the same area. Ecologists study communities to find out why and how different populations interact with each other.
EcosystemAn ecosystem includes all of the living organisms in a biological community and their interactions with the environment. Ecologists study ecosystems to find out how energy and nutrients are transferred among organisms in an ecosystem, as well as how different factors can affect the stability of ecosystems.
BiosphereThe biosphere is the sum of all living organisms and ecosystems on Earth. Ecologists study ecology at the biosphere level to explore migration (long-distance movement) patterns in animals, interactions between different ecosystems, as well as how global warming may affect different ecosystems.

Table showing the different levels of ecology

Succession is the process by which biotic and abiotic factors change over time in an ecosystem. There are main types of succession, primary succession and secondary succession.

Primary succession

In primary succession, newly formed rock is colonized by living organisms for the first time. The first species that colonize the region are called pioneer species. These species are specially adapted to living in very hostile environments, with little soil depth, water availability or other resources. An example of primary succession is the succession that occurs after a volcano has erupted.

Secondary succession

In secondary succession, an area that was previously already colonized is recolonized. An example of when secondary succession occurs is after a wildfire. Secondary succession happens much faster than primary succession, as the area has already been colonized before.

As succession progresses, the following trends happen;

  • Soil depth increases.

  • Water availability increases.

  • Biodiversity increases.

  • Soil quality improves.

The following trends happen up until a climax community is reached. The climax community is the point at which each biotic and abiotic factor can coexist in a stable environment. There are two types of climax community, a climatic climax and a biotic climax. A climatic climax is reached when abiotic factors determine the climax of the community. A biotic climax is the climax community reached when biotic factors determine the climax.

Insert figure on the levels of ecology

Ecology - Key takeaways

    • Ecology refers to how living organisms interact with each other and their physical environment

    • A biotic factor is a living component of the environment that affects how living organisms are distributed

    • An abiotic factor is a non-living component of the environment that affects how living organisms are distributed

    • Ecologists study ecology at many different levels

Final Ecology Quiz

Question

What are the two types of competition?

Show answer

Answer

Intra- and interspecific

Show question

Question

What is intraspecific competition?

Show answer

Answer

Competition between individuals of the same species.

Show question

Question

What is interference intraspecific competition?

Show answer

Answer

When more dominant individuals of a species have greater access to resources due to more aggressive behavior or the formation of specific territories.

Show question

Question

Which is an example of interference intraspecific competition?

Show answer

Answer

Large, dominant male saltwater crocodiles holding territories and refusing to tolerate other males. 

Show question

Question

What is exploitation intraspecific competition?

Show answer

Answer

When a specific resource is diminished or depleted by individuals from the same species population. 

Show question

Question

Which is an example of exploitation intraspecific competition?

Show answer

Answer

Brown bears preying upon salmon while side-by-side. 

Show question

Question

What is a major impact of intraspecific competition?

Show answer

Answer

A decrease in the rate at which populations grow.

Show question

Question

True or False: Exponential population growth is common.

Show answer

Answer

False.

Show question

Question

What is interspecific competition?

Show answer

Answer

Competition between individuals of different species.

Show question

Question

What is interference interspecific competition?

Show answer

Answer

When different species experience direct conflict over resources, territory, or something else. 

Show question

Question

Which is an example of interference interspecific competition?

Show answer

Answer

Saltwater crocodiles reducing the densities of Australian freshwater crocodiles through competition.

Show question

Question

What is exploitation interspecific competition?

Show answer

Answer

When different species indirectly compete over resources, which results in one specific benefiting and the other being deprived.

Show question

Question

What are the three types of exploitation interspecific competition?

Show answer

Answer

Classical exploitative competition

Show question

Question

What does Gause's Law propose?

Show answer

Answer

That two species competing for the same resources is unsustainable on the long term, resulting in the less dominant species being either pushed to extinction or evolving to take advantage of an available ecological niche. 

Show question

Question

What is it called when species evolve distinct traits in order to minimize competition?

Show answer

Answer

Character displacement

Show question

Question

True or False: Every living organism on Earth has limits to its population size.

Show answer

Answer

True

Show question

Question

The ecological factors that limit population growth are known as...

Show answer

Answer

Limiting factors

Show question

Question

The two types of limiting factors are...

Show answer

Answer

Density-dependent and density-independent

Show question

Question

Density-dependent limiting factors...

Show answer

Answer

Impact a population’s per capita rate of growth dependent on the population’s density.

Show question

Question

Which are examples of density-dependent limiting factors?

Show answer

Answer

Limitations on the food supply within an ecosystem.

Show question

Question

What is logistic growth?

Show answer

Answer

When density-dependent limiting factors cause population growth to gradually slow before reaching a maximum level at which growth will level off and become stable.

Show question

Question

What is exponential growth?

Show answer

Answer

When a population's growth rate remains constant, no matter the size, exceeding its carrying capacity.

Show question

Question

Density-independent limiting factors... 

Show answer

Answer

Impact a population’s per capita rate of growth independent of the population’s density.

Show question

Question

Top-down population regulation refers to...


Show answer

Answer

Situations where species at higher trophic levels control the populations of species at lower trophic levels.

Show question

Question

The cycles of growth followed by reductions in size are called...

Show answer

Answer

Cyclical oscillations

Show question

Question

True or False: The human population has a carrying capacity.

Show answer

Answer

True

Show question

Question

The human population has _____ in the last half century, which is more than in it has in the previous _____ years.

Show answer

Answer

more than doubled; at least 200,000

Show question

Question

What are some of the density-dependent limiting factors affecting the human population?

Show answer

Answer

Climate change

Show question

Question

If vegetation experiences a mass die-off, this may result in a decline in the mule deer population due to starvation. This, in turn, may also result in a reduction in the mountain lion population due to a lack of prey. This is known as...


Show answer

Answer

Bottom-up population regulation

Show question

Question

Mountain lions may control mule deer populations, but the mule deer may control the populations of certain plant species. This is known as...

Show answer

Answer

Top-down population regulation

Show question

Question

Limiting factors are...

Show answer

Answer

Density-dependent

Show question

Question

Over the past half century the human population has...

Show answer

Answer

More than doubled.

Show question

Question

Scientists believe that the population will peak at around...

Show answer

Answer

10-11 billion people.

Show question

Question

Unsustainable human population growth is one of the major driving factors behind...

Show answer

Answer

Loss of biodiversity

Show question

Question

What are some of the factors that have allowed for exponential human population growth?

Show answer

Answer

Advances in medical technology

Show question

Question

In his 1968 book The Population Bomb, this biologist predicted dire consequences for humanity due to overpopulation.

Show answer

Answer

Paul Ehrlich

Show question

Question

In 1979, China introduced a _______ in an attempt to control its population growth.

Show answer

Answer

One-child policy

Show question

Question

What are some humane methods to mitigate the negative consequences of human population growth?

Show answer

Answer

Increased access to contraception. 

Show question

Question

Exponential growth produces a...

Show answer

Answer

J-shaped curve.

Show question

Question

Logistic growth produces a(n)...

Show answer

Answer

S-shaped curve.

Show question

Question

The ____-shaped curve is, by far, the most common in nature.

Show answer

Answer

S

Show question

Question

The human population has, thus far, produced a ______-shaped curve, indicating _________ population growth.

Show answer

Answer

J; exponential

Show question

Question

The approximate human population growth rate today is _______ annually.

Show answer

Answer

1.1%

Show question

Question

The earliest population estimates for modern humans 200,000 years ago range from _____________ people.

Show answer

Answer

100,000-300,000 people.

Show question

Question

Currently, the three countries with the largest populations are...

Show answer

Answer

China

Show question

Question

Communities in ecosystems are... 

Show answer

Answer

Constantly experiencing disturbances that cause structural changes.

Show question

Question

The process of constant disturbances and their resulting structural changes to species and habitat over time is known as...

Show answer

Answer

Ecological succession

Show question

Question

What are the two kinds of ecological succession?

Show answer

Answer

Primary and secondary

Show question

Question

This kind of ecological succession occurs when a previously lifeless, non-existent, or obscured habitat is colonized by species for the first time.

Show answer

Answer

Primary succession

Show question

Question

This kind of ecological succession occurs when some ecological disturbance causes habitat that was colonized by organisms previously to have much of its animal and plant life disappear, eventually resulting in recolonization of the habitat.

Show answer

Answer

Secondary succession

Show question

60%

of the users don't pass the Ecology quiz! Will you pass the quiz?

Start Quiz

Discover the right content for your subjects

No need to cheat if you have everything you need to succeed! Packed into one app!

Study Plan

Be perfectly prepared on time with an individual plan.

Quizzes

Test your knowledge with gamified quizzes.

Flashcards

Create and find flashcards in record time.

Notes

Create beautiful notes faster than ever before.

Study Sets

Have all your study materials in one place.

Documents

Upload unlimited documents and save them online.

Study Analytics

Identify your study strength and weaknesses.

Weekly Goals

Set individual study goals and earn points reaching them.

Smart Reminders

Stop procrastinating with our study reminders.

Rewards

Earn points, unlock badges and level up while studying.

Magic Marker

Create flashcards in notes completely automatically.

Smart Formatting

Create the most beautiful study materials using our templates.

Sign up to highlight and take notes. It’s 100% free.