3. Definition: Population help one another and either one or
both the species are befitted.
• This benefit may be regarding the food, shelter, substratum or
transport.
• Co-oparative relationships between species that result in
better growth, reproduction and survival for at least one
species without affecting the other.
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1. Positive interactions
5. • Mutualism is an obligatory positive interspecific interaction that is strongly
beneficial to both species. In past, it was termed symbiosis.
• In this case, both of the species derive benefit and there exists a close and
often permanent and obligatory contact which is more or less essential for
survival of each.
• In this type, two populations enter into some sort of physiological exchange
and resulted in coevolution of both species.
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1.1 Mutualism
6. POLLINATION BY ANIMALS
Certain insects such as bees, moths, butterflies, etc. and birds derive food from
the nectar, pollen ,and in return bring about cross pollination.
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Examples for Mutualism
7. Mutual defence in ants
and acacias
Red billed oxpeckers
and Impala
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8. LICHENS
They form example of mutualism where contact is close and permanent as well
as obligatory.
• The body of lichens is made up of a matrix formed by a fungus, within the cells
of which an alga is embedded. The fungus makes available the moisture and
minerals to the algae, which prepare food by photosynthesis.
• In nature, neither of the two can grow alone independently. They tend to grow
abundantly on bare rock surface.
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11. SYMBIOTIC NITROGEN FIXATION
• Bacterium Rhizobium forms nodules in the roots of leguminous plants and
lives symbiotically with the host.
• Bacteria get a protective space to live in and derive prepared food from the
roots of higher plants and in return fix gaseous nitrogen.
• The leguminous plants use this nitrogen in the protein synthesis.
• Nitrogen fixation like association also occurs in root nodules of Alnus,
Casuarina , Cycadacease , Podocarpus ,etc.
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14. MYCORRHIZA
• In mycorrhizal association, tree root become infested with fungal hyphae.
• The fungi give their food from the tree roots and their hyphae supply water
and minerals that they absorb from the soil much like the root hairs of trees.
• It is believed that the fungus also regulates the PH.
• Mycorrhizae may be on the surface of roots (ectotropic) or inside between the
cells of the roots (endotropic). Ectotropic mycorrhizae are common in nature
on pines, oaks, beech and endotropic.
• The other similar root associations are met with actinomycetes in form of
nodules and with some blue-green algae such as Anabena and Nostoc forming
coralloid roots of Cycas.
• Both of these kinds of associations are connected with nitrogen fixation by
microscopic organisms present in the roots.
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19. VAM (VESICULAR –ARBUSCCULAR MYCORRHIZA)
• VAM is formed by the symbiotic association between certain phycomycetous
fungi and angiosperm roots.
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Mycorrhiza is the product of an association between a fungus and plant root. Vesicular-arbuscular
mycorrhiza (VAM) is formed by the symbiotic association between certain phycomycetous fungi and
angiosperm roots.
The fungus colonizes the root cortex forming a mycelial network and characteristic vesicles (bladder-like
structures) and arbuscules (branched finger-like hyphae). The mycelia are aseptate or septate ramifying
intracellularly thus causing little damage to tissues. The arbuscular are the most characteristic structures,
formed intracellularly and probably having an absorptive function.
The vesicles are terminal swellings of hyphae formed inter and intracellularly having a storage function.
There are six genera of fungi belonging to Endogonaceae which have been shown to form mycorrhizal
associations: Glomus, Gigaspora, Acaulospora, Entrophospora Sclerocystis and Scutellospora.
These are mainly identified by their characteristic spores and sporocarps which are formed mostly in the soil
surrounding the roots and rarely inside the roots. The identification of VAM fungi directly from roots has
been difficult. One of the striking features of VAM fungi is their very wide host range which includes
angiosperm species belonging to almost all the families. Even the roots of some aquatic plants are colonized
by VAM fungi.
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• Mycorrhiza Bio-fertilizer is also known as VAM (Myco = Fungal +
rrhiza = roots) adheres to plants rhizoids leading to
development of hyphae.
• Hyphae boost development and spreading of white root in to
soil leading to significant increase in rhizosphere.
• These hyphae further penetrate and form arbuscular within the
root cortical.
• VAM fungi form a special symbiotic relationship with roots of
plant that can enhance growth and survivability of colonized
plants.
• Mycorrhiza Bio fertilizer is very useful in organic farming as well
as normal commercial farming Mycorrhiza Bio fertilizer.
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It is a type of relationship in which one organism is benefited while the other is
no significant effect on it.
Commensalism is a long-term biological interaction (symbiosis) in which
members of one species gain benefits while those of the other species neither
benefit nor are harmed. This is in contrast with mutualism, in which both
organisms benefit from each other; amensalism, where one is harmed while the
other is unaffected.
1.2. Commensalism
25. Commensalism-like associations
• It exist between a variety of
micro organisms and higher
plants.
• For example: The zone of soil
around the roots of higher
plants characterized by intense
microbial activity ,called the
rhizosphere.
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26. • This is less extreme sort of interaction than mutualism in which the interaction is
clearly beneficial to both species, allowing the equilibrium population levels. The
association is not an obligatory one. Both populations are capable of surviving in their
natural environment on their own.
• The term syntrophism is applied to the interaction of two or more population that supply
each other nutritional needs.
• Syntrophism may allow microbial population to perform activities, such as the synthesis of a
product, that neither population could perform alone.
• The synergistic activities of two microbial population may allow completion of a metabolic
pathway that otherwise could not completed.A classic example is exhibited by Enterococcus
faecalis and Escherichia coli.
• Neither organism alone is able to convert arginine to putrescine.E.faecalis is able to convert
arginine ornithine,which can be then utilized by the E.coli population to produce putrescine.
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1.3. Protocooperation
28. 2.1. Exploitation
• In this one species harm the other by making its direct or indirect use of
support, shelter or food.
The following are the types:
• 2.1.1. Social parasitism: It describes the exploitation of one species by another,
for various advantages.
• --Egg parasitism: old world cuckoos and brown headed cowbirds of north
America, both do not build nests of their own rather deposit their eggs in nests
of other species.
• --Brood parasitism: Indian koel and crow
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2. Negative Interaction
31. 2.1.2. Parasitism
• Organisms which live on or within the body of the other organisms (host) and
derive their food from them. Most of the parasite harm their host.
• Parasitism is of two types
• Ecotoparasitism :- parasites that lives on the external surface of the host.
• Example:- Lices on human body dosnot enter on human body but gets its food.
Cuscuta is a non green plant grows on other green plants. It derives all
nurtients from green plants
• ENDO PARASITISM:- parasites that live inside the body of the host.
• Ex:- malarial parasite which enters human body by a mosquito bite and causes
infection.so that person suffer from malaria.
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35. 2.1.3. Predation
• In this category generally the predator feeds on the prey spices by killing
it. The predator-prey interactions are of short durations and the
predator usually larger than prey. The predator species derive nutrition
from prey spices.
Example-Nematode trapping fungi
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39. In this interaction one participant is harmed while the other remains neutral
(neither benefit nor loss).
One participant usually produces toxic substances or chemicals which harm the
organisms closely associated with it.
Ex:- The antibiotic producing strains of Penicillium species especially Penicillium
notatum which supress the growth of most bacteria (gram +ve ).
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2.2. Amensalism
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This involves the competition among different organism for limited available
resources. This competition out to be good for one animal and bad for other.
This competition can be interspecies also. In this inferior one will be eliminated
eventually.
Examples of interspecies competition:
Dolphins go along together and play with each other but when its time to eat all
dolphins have to compete for a meal.
Interaction between Fungi and Bacteria.
2.3. Competition
