Ecological niches - forest ecosystem with diverse species

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DP Biology

Ecological Niches

Ecological niches diagram

Imagine looking through a forest, a pond, or even your backyard. There are many different types of species living next to each other. Some climb trees while others dig into the dirt. Others swim about in the water. Have you ever thought about how they are able to live next to each other without one species dominating everything? The answer is ecological niches.

Ecological niches help to explain different ways in which different organisms interact with one another and with the environment. They help explain how species can live next to each other, compete, and how they further evolve in that particular ecosystem.

What Is an Ecological Niche?

An ecological niche is how a particular species of an organism fits or fits into an environment.

  • What ecosystem is it part of
  • Its feeding behavior
  • Its daily activities
  • Relationships with other organisms
  • Strategies to ensure its presence and reproduction

Niche is not a space; it's a job. It's how a species survives, lives, and interacts with its biome.

Take, for example, a frog in a pond. Yes, that's its habitat, but it also does other things. It eats insects, and in addition to other activities like creating a home and breeding in it, it can be at risk of being captured by a bird. A frog has a niche that is not just its environment.

Niche and Habitat

Habitat

Desert, pond, forest.

A habitat contains several organisms, among which each has a different role and function in the ecosystem to avoid competition.

Niche

Role of the organisms and their way of life.

Rainforest inhabitants are divided into different roles. For example, the branches are home to the monkeys. The ground is where the jaguars are stationed. The epiphytic plants are also located on the branches.

Fundamental and Realized Niches

The two types of niches can be explained with the following terms used by ecologists:

Fundamental Niche

This niche has no competition. As a result, the species can realize its full potential regarding the temperature, light, water, salt, or other factors. From an ecologist's standpoint, think of it as the ideal career plan.

Realized Niche

This involves limiting factors, be they competition, prey, or other factors. Competitive species tend to occupy the niche. It is the location where a species is found, and the resources it uses.

The two species of barnacles represent a classic example. They inhabit the same zone. One barnacle can extend her reach to the entire zone, but due to competition, she is confined to a zone. This has a resemblance to the concept of realized niche.

All factors considered, balance is critical, given that niches are drawn from the potential of species and the resources available.

Niche Overlap and Competition

When two species compete for the same resources, we say their niches overlap, and the result will be competition.

Types of Competition:

Interspecific Competition

Competition between different species.

Example: Two species of birds compete for the same species of insects.

Intraspecific Competition

Competition between individuals of the same species.

Example: Two rabbits compete for the same type of food.

Competitive Exclusion Principle

Two species cannot coexist in the same niche for a long time. One of the species will be outcompeted and go extinct or relocate elsewhere.

This was first noted by Gause (1934) in his research on Paramecium species.

Example: If two species of mice compete for the same species of food and habitat, one of the species will be outcompeted and go extinct or relocate to a different habitat.

This principle shows that the coexistence of different biological species is the result of small changes. By evolving slight behavioral changes, or changes in the way resources are utilized (resource partitioning), species can coexist without completely replacing each other.

Resource Partitioning

Resource partitioning is the phenomenon where an ecosystem manages to balance the competition of different species or the resources that they depend on, and allows them to coexist in the same area.

To survive without fighting, organisms often split resources so as not compete. This method is called resource partitioning.

  • Different species will feed in different areas, at different times, or eat different foods.
  • Resource partitioning can happen in space, time, or by diet. It decreases competition and allows organisms to survive together.
  • Different birds can search for food in the same tree. One bird can eat the bugs that are in the flower. Another bird can eat the bugs in the bark. Another bird can eat the insects in the leaves.
  • Also, different food sources can be bats and birds.

In a desert ecosystem

Consider the case of a species that lives in a desert ecosystem. The desert cacti are an organism that displays particular adaptations. It has a thick stem that is able to store water, and the spines protect the organism from herbivores that may eat it. The shallow roots enable the organism to absorb the rainwater quickly.

Such adaptations also help the organism to survive in the desert ecosystem and compete with different organisms within the same niche.

Different species can also be grouped based on the resources that they are competing for.

Niche and Adaptations

Niche width is classified as either narrow or broad.

Generalist Species

Having a wide niche, and surviving in many different habitats.

Example: A raccoon can eat a variety of foods, from plant-based foods to insects, eggs, and even human food.

Specialist Species

Having a narrow niche and are hyper-adapted to survive in extreme conditions or feast on a specific type of food.

Example: A specific species of insect that eats only one type of plant. Koalas only consume eucalyptus trees.

Importance: Generalist species' niche is able to adapt to competition, while specialist species are efficient in their niche but have lost vulnerability as the conditions change.

Keystone Species

Some species have a fundamental role in nature, as they keep a certain structure in the ecosystem. These species have a large impact on other species in a niche. A keystone species provides support to the ecosystem as a whole.

Example:

  • A good example of this is the sea otter. She eats sea urchins and prevents the overgrazing of kelp forests.
  • Beavers build dams, creating wetlands that support many species.
  • Some predators, such as wolves, hold the population of herbivores in check, preventing overgrazing and maintaining biodiversity.

Species that fit into many categories in a food web are known as? They show how a single niche impacts the entire system.

Niches in the Real World

Niche in the Forest Ecosystem

  • The trees allow the forest to have a canopy and provide shade.
  • Birds get food from the different layers by eating insects in one, fruits in another, and seeds in yet another.
  • Pollinators and decomposers are insects that help break down dead things.
  • Mammalian ground dwellers consume the seeds, fungi, and insects.

Niche in the Aquatic Ecosystem

  • Depending on the amount of depth, light, and available food, different fish occupy different niches.
  • In each tier of the food web, the larger fish consume the smaller fish, and the smaller ones consume the phytoplankton.
  • Amphibians that are in the water breed there, but they feed and forage on the land.

Niche in the Urban Ecosystem

  • Urban nests and thrived litter by pigeons, seeds acted as food to sparrows, and small mammals became food for foxes.
  • Each species occupies a niche to reduce direct competition.

Niche Dynamics and Environmental Change

Niches are dynamic, not fixed, and they change because of:

  • Resource availability: Seasonal changes in food or in water.
  • Predation pressure: Addition or deletion of a predator.
  • Human impact: Habitat destruction, pollution, and climate change.
  • Invasive species: New species can change the niches of the native species.

Example:

  • The North American Introduction of the zebra mussel changed the niche of the native mussels and fish.
  • Urbanization alters the niches of some species, causing some of them to become nocturnal or to scavenge on rubbish.

Species that can't change their niche may adapt, migrate, or face extinction.

Summary

  • An ecological niche is the role and lifestyle of a species in its habitat.
  • The difference between habitat and niche is: Habitat = where, Niche = how.
  • Fundamental niche = possible (theoretical) conditions in the absence of competition.
  • Realized niche = actual (observed) conditions in the presence of interactions.
  • Competition happens in niches that overlap.
  • Competitive exclusion principle: species cannot occupy the same niche forever.
  • Resource partitioning = division of resources to lessen competition.
  • Niche width: generalists (wide), specialists (narrow).
  • Adaptations = traits that allow efficient niche use.
  • Keystone species = species whose niche drastically alters the ecosystem.
  • Niche dynamics refer to the combination of environmental elements, human interaction, and invasive species that impact niches.
  • Studying niches in ecosystems provides insight into the connections between species, ecosystem diversity, and how the overall system helps maintain a balanced state.
  • In Biology, this is similar to the interrelations of the population, community, and ecosystem levels of biology. The study of niches is essential for mastery of ecological succession, trophic dynamics, and conservation biology.
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