Biotic Factors and Species Interactions in Ecosystems

Biotic Factors in Ecosystems

Biotic factors are the living beings that inhabit an ecosystem and the relations established between them.

• The individuals of the same species are grouped into populations.
• All plants, animals, and microorganisms that inhabit a territory constitute a community.

Intraspecific Associations

Individuals of the same species generally live together to improve their defense and food search; these are known as intraspecific associations.

Types of Intraspecific Associations

• Colonial: Consists of bodies joined together and interconnecting that originate from a common progenitor. Example: Coral colony.
• Gregarious: Formed by individuals from different families to achieve a common goal. Example: Schools of fish or herds of deer.
• State or Social: Formed by individuals with anatomical and physiological differences where there is a division of labor. Example: A honeycomb.

Interspecific Associations

These are associations established directly between individuals of different species. In some associations, individuals compete for the same food or feed on one another through competition, predation, and parasitism.

Competitive and Harmful Interactions

• Competition: Two individuals of different species struggle to achieve a benefit, a territory, or food. Example: Leopard and lion.
• Predation: An individual of one species hunts, pursues, and captures another of a different species to feed. The beneficiary is the predator. Example: Wolf and lamb.
• Parasitism: An individual lives at the expense of another, which seriously harms the host and may even cause death. The parasite is the smaller beneficiary. Example: Flea and dog.

Beneficial Interspecific Associations

Other associations between different species occur where one individual benefits or both provide mutual benefit, such as commensalism, symbiosis, and inquilinism.

• Commensalism: One species benefits without the other being affected. Example: Shark and remora fish.
• Symbiosis: Individuals of two or more different species are associated and both benefit. Example: Alga and fungus.
• Inquilinism: An individual is associated with another of a different species that serves as housing. Example: Tree and squirrel.