LWE: Lesson - Introduction to Ecosystems (Topic 1.1) 📖

⏳ Estimated Reading Time: 6 - 8 minutes

Explain how the availability of resources influences species interactions.

a coral reef teeming with numerous coral, fish, algae, and invertebrate species. — ***A coral reef teeming with many species interacting together.***

Ecology is the study of how an organism interacts with its environment. In this lesson, we'll dive into the basics of ecological relationships. Grasping the dynamics of predator-prey interactions, symbiosis, and competition is essential to understanding ecosystems. Throughout this lesson, we'll break down these concepts, making sure you gain a solid understanding of how organisms coexist and interact within ecosystems. Let's explore the fundamental principles that shape life on our planet!

Predator-Prey Relationships

A majestic bald eagle descends toward the water, wings outstretched, against a clear blue sky. Below, a fish breaks the surface, creating a powerful visual contrast between sky and sea. — **If the eagle eats the fish, who benefits? Who is harmed?**

Predator-prey relationships are crucial ecological interactions shaping ecosystems. In these relationships, one organism, the predator, hunts and feeds on another, the prey.

If an eagle eats a mouse, the eagle is the predator, and the mouse is the prey. This is a positive interaction for the eagle because the eagle is gaining energy from his meal of mouse. This is a negative interaction for the mouse, however, because the mouse dies.

Technically, an herbivore eating a plant is also considered predation because the herbivorous animal is preying on the plant, but we don't usually refer to these relationships this way.

Evolutionary Arms Race

Predators have evolved various adaptations for efficient hunting, including keen senses and specialized features like claws or teeth.

Prey species also develop adaptations to help them avoid predation. Prey usually have some type of camouflage for blending into their surroundings, mechanical adaptations to defend themselves against predators, chemical adaptations to sicken potential predators, or mimicking a prey species with a defensive adaptation.

Explore the activity below to see some examples of prey adaptations:

Predator-prey relationships are often evolutionary arms races between predators’ ability to find prey and prey’s ability to escape predators. This arms race creates competition between predator-prey species. For example, if a prey species has developed camouflage that is too good, then predators often develop adaptations that allow them to smell their prey, so they can still find them.

Each organism is designed to maximize its ability to get the resources they need to survive.

Essential Knowledge

In a predator-prey relationship, the predator is an organism that eats another organism (the prey).

Symbiotic Relationships

an orange, black, and white clownfish swimming in a pink sea anemone — ***Clownfish live in close relationship with sea anemones. This relationship is a specific type of symbiosis known as a mutualism.***

Symbiosis, from the Greek words "sym" (together) and "biosis" (living), represents a cooperative partnership between different species. The distinction of two species is important – if two members of the same species are living together in close association, it is not symbiosis.

There are a variety of symbiotic relationships, depending on who is benefiting from the interaction. In this course, we will focus on the three most common types of symbiosis - mutualism, commensalism, and parasitism.

Explore the tabs below to learn more about each type of symbiosis:

Mutualism

Mutualisms are symbiotic relationships that are beneficial to both species. The word “mutual” actually means “good for both.” Explore some examples of mutualisms from the animal kingdom:

Parasitism

A close-up of a mosquito with black and white markings on its body, resting on human skin. The mosquito’s long legs and wings are clearly visible, and the texture of the skin can be seen in detail.” — ***The mosquito is a parasite, and the human is the host.***

Parasitism is a type of symbiotic relationship where one member benefits and the other is harmed, but the prey is usually NOT killed.

The organism that is doing the harm is the parasite and the organism being harmed is the host.

For example, if you get a bacterial infection, you will get sick, but it is unlikely you will die.

For a parasite, it is to their advantage NOT to kill you. If a parasite kills its host, the organism they are feeding off, it loses its home and meal. Therefore, it’s much more advantageous for the parasite to harm you, but not kill you. Parasites that kill their hosts are not effective parasites because they quickly become homeless and without food.

Symbiosis is a close and long-term interaction between two species in an ecosystem.

Types of symbiosis include mutualism, commensalism, and parasitism.

Niches

An image of a blackburnian warbler on the top and a black-throated warbler on the bottom. — ***The Blackburnian Warbler nests and feeds on insects high in the trees. The black-throated warbler does the same throughout the forest.***

A niche is an individual’s specific place in an environment, including habitat, diet, behavior, social structure, physical adaptations, and reproductive strategies. There are two types of niches – fundamental and realized. A fundamental niche is the total niche an organism could occupy if there was no competition, and the entire ecosystem was available to them.

Let's look at two species of warblers to explain this concept.

While the black-throated warbler could hunt and nest in the upper canopy as well as the middle and lower parts (its fundamental niche), its realized niche is the lower and middle canopy to avoid competing with the Blackburnian warbler.

A niche is an individual's specific place in an environment.

Competition

Competition is when two species compete for a resource and occurs when a resource is limited. Explore the tabs below to learn more about each type of competition.

INTRAspecific
INTERspecific

INTRAspecific Competition

a painting of an oak forest. By Ivan Shishkin — *These oak trees are the same species, fighting for resources like sunlight, water, and soil nutrients. Taller trees block the sun for the smaller ones and their roots compete for water and nutrients.*

Members of the same species can compete with each other, and this is known as intraspecific competition. Intraspecific competition provides a way for populations to self-thin. As the population becomes more crowded, they will begin to compete more and more for the same resources.

Territoriality is also a type of intraspecific competition, because members of the same species, usually males, are competing for the resource of space.

Territoriality is an advantage to populations that require large spaces because this allows members of the species to disperse, stabilizing their populations, and allowing each member to get the resources they need.

Intraspecific competition is also why the juveniles of many species feed on different resources than the adults of the same species. This allows the juveniles to feed as much as they need/want to grow and not compete with the adults in that population.

an image of a male robin, with a black back and a red-orange belly — ***Male robins make and guard territories to find mates and nest well, fighting off other male robins.***

Territories in robin populations serve as spaces for nesting, foraging, and raising offspring. The male robins use vocalizations and displays to communicate the boundaries of their territories to other males.

Interactions between males may involve aggressive behaviors to establish dominance and defend their exclusive access to resources within the territory.

Competition can occur within or between species in an ecosystem where there are limited resources.

Resource partitioning - using the resources in different ways, places, or at different times - can reduce the negative impact of competition on survival.

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