POPULATION INTERACTION

What is population interaction ?Biological interactions are the effects

that the organisms in a community have on one another. In the natural world no organism exists in absolute isolation, and thus every organism must interact with the environment and other organisms.

Population of two species may interact in ways that correspond to combination of neutral, positive and negative

Three of these combinations (+, +) (-, -) (+, -) are subdivided resulting in NINE important interactions & relationships.

9 Types of interactions 1) Neutralism2) Direct Interference3) Resource type competition4) Amensalism5) Commensalism6) Parasitism7) Predation8) Protocooperation9) Mutualism

CLASSIFICATION OF INTERACTION

Negative interactions-NeutralismDirect interferenceCompetition for resourceAmensalismParasitismPredation

Positive interaction-CommensalismProto co-operationMutualism

NEUTRALISMNeutralism describes the relationship

between two species that interact but do not affect each other.

Neither of the population is affected by interaction with each other

Example : Rabbits, deer, frogs, live together in a grassland with no interaction between them.

DIRECT INTERFERENCECompetition, direct interference type is the type

of interaction where both populations actively inhibit each other

Occurs directly between individuals via aggression etc. when the individuals interfere with foraging, survival, reproduction of others.

Example seen between the ant Novomessor cockerelli and red harvester ants, where the former interferes with the ability of the latter to forage by plugging the entrances to their colonies with small rocks.

RESOURCE TYPE COMPETITION

Competition is an interaction between organisms or species in which both the species are harmed. 

Limited supply of at least one resource used by both can be a factor.

 Competition among members of the same species is known as intraspecific competition

While competition between individuals of different

species is known as interspecific competition.

AMENSALISM It is an antagonistic interspecific interaction in

which one species is inhibited while other species is neither benefitted nor harmed.

It is also called antibiosis and the affected species is called amensal and the affecting species is called inhibitor.

Example:-Roots of certain plants produce allochemic substances which check the growth of other plants to conserve resources, such as, Convolvulus arvensis, a weed inhibits the germination and growth of wheat.

COMMENSALISMCommensalism, is a class of relationships between

two organisms where one organism benefits from the other without affecting it.

The commensal (the species that benefits from the association) may obtain nutrients, shelter, support, or locomotion from the host species, which is substantially unaffected.

The commensal relation is often between a larger host and a smaller commensal; the host organism is unmodified, whereas the commensal species may show great structural adaptation consonant with its habits,

as in the remoras that ride attached to sharks and other fishes(example).

COMMENSALISM

PARASITISMParasitism is a non-mutual symbiotic

 relationship between species, where one species, the parasite, benefits at the expense of the other, the host.

Parasites can be micro parasites, which are typically smaller, such as protozoa, viruses, and bacteria Examples of parasites include the plants mistletoe and cuscuta, and animals such as hookworms.

Parasites typically do not kill their host, are generally much smaller than their host, and will often live in or on their host for an extended period.

PREDATIONIt is a negative, direct food related

interspecific interaction between two species of animals in which larger species called predator attacks, kills and feeds on the smaller species called prey.

Predator population adversely affect the growth and survival of smaller prey population and therefore predation is considered an antagonistic interaction.

Example:- Plant like Nepenthes (pitcher plant), Drosera (sundew), Dionoeae (Venus fly trap) etc. feed on insects to fulfil their nitrogen requirement.

Some predators (such as frog) act as prey for others (snake) which in turn are prey to a higher carnivores (eagle).

Examples for predation

Significance of predation a) Local species diversity is directly

related to the efficiency with which the predators prevent the monopolization of an environmental area by any species.

b) Predation keeps the prey population under check, so as to maintain an ecological balance. Weak and less efficient members in the prey population are removed.

d) Most important significance is in the practical utility of prey predator relationship on biological control of weeds and pests. Many insect pests are kept under check by introducing their predator into the area. For e.g., Opuntia which become a serious problem in Australia was brought under control by introducing its natural herbivore Cactoblastis (cochineal insects).

PROTO COOPERATION It is a positive inter specific interaction in

which both the partners are mutually benefitted and increase the chance of their survival.

However, the interaction is not obligatory for their survival as both can live without this interaction.

Example:-  Crocodile bird (Pluvianus aegyptius) enters the mouth of the crocodile and feed on parasitic leeches. By this the bird gets food and the crocodile gets rid of blood sucking parasites.

Positive interspecific relation between crocodile bird and crocodile

MUTUALISMIt is a positive interspecific interaction in which

members of two different species favour the growth and survival each other and their association is obligatory.

Both the partners are benefitted by this interaction.Mutualism is also referred as symbiosis or symbiotic

interaction and the partners are referred as symbionts.

Example:- Termites (white ants) are not capable of digesting wood, which they ingest as food. A multi flagellate protozoan Trichonympha campanula, which lives in the intestine of white ant secretes cellulase enzyme to digest the cellulose of wood. In return, the ant provides food and shelter to the protozoan.

Termites play important ecological role as decomposers by increasing the turnoverAnd degradation

Thank you

REFERENCESWEBSITES-www.tutorvista.com/content/biologywww.wikipedia.orghttp://www.physicalgeography.net/

fundamentalsBOOKS-Fundamentals of ecology Fifth Edition

by Eugene P. Odum & Gary W. Barrett