Types of ecological relationships
Living organisms constantly interact with each other. Interactions between organisms, as well as their influence on living conditions, are a combination of biotic environmental factors.
All relationships between organisms are divided into 6 groups (or types).
We will call them using the following notation for each of the interacting species:
(+) – the species gains an advantage (positive impact);
(-) – the species is negatively affected;
(0) – there is no harm or benefit for the species.
(0 0) Neutralism – organisms do not act on each other in any way.
(- 0) Amensalism – one species is oppressed, while the other is indifferent to these relationships.
(+ 0) Commensalism – unilateral use of one type of organism by another without harming it (varieties – parasitism, companionship, lodging).
(+ +) Symbiotic relationships – mutually beneficial beneficial connections between organisms (varieties – protocooperation, mutualism, symbiosis).
(+ -) Predation is a type of relationship between populations in which representatives of one species eat (destroy) representatives of another;
(+ -) Parasitism is a form of relationships between species, in which organisms of one species (parasite, consumer) live off nutrients or tissues of another species (host) for a certain time.
(- -) Competition is a relationship that is harmful to both organisms.
Environmental relationships that are indifferent to one (or both) partners
Let’s consider examples of these ecological interactions. Let’s start with a relationship that is indifferent to one (or both) partners.
Neutralism (00) – organisms do not influence each other.
Example: moose and squirrels in the same forest.
In nature, true neutralism is very rare, since mediated (indirect) interactions are possible between all species, the effect of which we do not see simply due to the incompleteness of our knowledge.
Amensalism (- 0) – one species is oppressed, the other does not benefit.
For one of the cohabitating species, the influence of the other is negative (it experiences oppression), while the oppressor receives neither harm nor benefit.
Example: Light-loving grasses growing under trees suffer from heavy shading, while the tree itself does not care.
Commensalism (+ 0) – one species (commensal) receives any advantage, benefit, without bringing any harm or benefit to the other.
Unilateral use of one type of organism by another without harming it. Relationships that are beneficial for one of the interacting species and neutral for the other (a transitional form from neutralism to mutualism).
Example: some mammals (wolves, foxes, moose, deer) carry fruits and seeds with various hooks and notches (like a string and burdock) on their fur. Such interaction is useful for plants, but animals are indifferent to it.
This type of relationship is fairly common. There are varieties of commensalism.
Freelogging is the consumption of the host’s food leftovers.
Example: Stickfish are frequent companions of sharks. Their front dorsal fin has been transformed into a suction cup, which allows them to stay on the shark’s body, constantly following it. This cohabitation is neutral for the shark, but benefits the adherent fish (providing food and facilitating movement).
Co-eating is the consumption of different substances or parts of the same resource.
Example: the relationship between different types of soil bacteria-saprophytes, processing different organic matter from rotted plant residues, and higher plants, which consume the resulting mineral salts.
Lodging is the use by some species of others (their bodies or their dwellings) as a refuge or dwelling.
Example: the relationship between plants and hollow nests (in the photo there is a tawny owl near a hollow tree). Those of the birds and animals that inhabit the already existing hollows, thereby do not harm the trees, but also do not bring any benefit.
Example: This type of relationship is widespread in plants. In tropical forests, epiphytes are widespread – plants that settle on the trunks and branches of other plants. Moving to the trees, they climbed from dusk to light. They do no damage to trees, and they receive water and nutrients from the atmosphere.
Example: lodging is also found in animals. So, small insects and spiders can live in a double squirrel.