Interactions among species is divided into two categories:
- Intraspecific: It is type of interaction that occurs between populations of same species. Example: Social, family, cannibalism etc.
- Interspecific: It is type of interaction that occurs between population of different species. Example: Parasitism, Predation, Mutualism etc.
The interactions are usually indicated in ‘+, -, 0’ form regarding both partners as following:
Plus sign ‘+’ indicating benefit.
Minus sign ‘-’ indicating harm/inhibition.
Zero ‘0’ indicating neither benefit nor harm i.e. neutral.
|S. No.||Type Of Species Interaction||Species A||Species B|
1) Neutralism: (0, 0)
- When populations of two species coexist in an ecosystem with neither affecting the other.
- Example: In desert, Cactus & Tarantulas co-exist with no or insignificant interaction.
2) Commensalism: (+, 0)
- When one species population is benefitted (commensal) while other remains unaffected (host).
- ‘Commensal’ means ‘eating at same table’.
- Types of commensalism:
- Phoresis: (Phoresis = to carry)
- The phoront is carried in/on by the host from one place to another.
- Purpose is transportation/dispersal. No metabolic/feeding interaction occurs in between them.
- It can be facultative or obligatory.
- Example: Pseudoscorpion (Cordylochernes scorpioides)is usually found under the elytra of harlequin beetle (Acrocinus longimanus).
- Inquilism: (Inquilism = tenancy)
- Inquiline lives as commensal in nest, burrow or dwelling place of the host.
- Example: Habrotrocha rosa lives in pitcher of Sarracenia purpurea (Purple pitcher plant).
- One organism creates suitable environment for living of other organism.
- Example: Hermit crabs live in the shell of gastropod to protect their body.
- Phoresis: (Phoresis = to carry)
3) Protocooperation: (+, +)
- Populations of both species are benefitted by the interaction.
- Interaction is not obligatory.
- Also called facultative cooperation or facultative mutualism.
- Example: Sea anemone (Adamsia palliata) attached to shells of hermit crab (Eupagurus prideauxi).
4) Mutualism: (+, +)
- Populations of both the species are benefitted.
- Interaction is obligatory i.e. neither can survive without the other under natural conditions.
- Example: Lichens
5) Amensalism: (0, -)
- One species population is inhibited but other remains unaffected i.e. this interaction is detrimental to one while other is not affected.
- Example: Release of certain toxins by one plant species inhibits growth of the other.
6) Parasitism: (+, -)
- Parasitism is a type of interspecific relationship in which one organism (parasite) is metabolically dependent on the other (host).
- The parasite benefits at the expense of the host and is also usually smaller in size than its host.
- Parasitic relationship is said to obligatory as normally the parasite cannot survive without its host
- Example: Ticks & Leeches are blood sucking parasites.
7) Predation: (+, – )
- Type of interspecific interaction in which one organism (predator) obtains food energy by consuming the other organism (prey), usually after killing it.
- Predation also includes grazing by herbivores.
- In contrast to parasitism, predator is usually larger than prey & prey is killed by the predator for food.
- Example: Lion kills a zebra & consume it.
8) Competition: (-, -)
- Interspecific competition – Interaction between populations of different species at same trophic level, which adversely affects one/some or all the interacting species. Example: Lion & Tiger compete for same deer for food. [Intraspecific Competition discussed under Intraspecific Interactions]
(Symbiosis = living together)
- It is a type of close or intimate relationship among organisms of different species.
- Members of symbiotic relationship are called symbionts.
- Commensalism, Parasitism & Mutualism are considered symbiotic relationships.
To be continued…