This document discusses different types of biological interactions between species: mutualism, amensalism, commensalism, and parasitism. It provides examples for each type of interaction. Mutualism benefits both species, such as the relationship between plants and mycorrhizal fungi. Amensalism harms one species without affecting the other, like competition between trees and saplings. Commensalism benefits one species without affecting the other, exemplified by phoretic mites on insects. Parasitism benefits one species at the expense of the other, illustrated by tapeworms living in mammalian guts.

1. BY:
MARIYAM NAZEER AGHA
KUD NO: 15S14233
DEPT. OF STUDIES IN ZOOLOGY
GOVT. ARTS AND SCIENCE COLLEGE, KARWAR

2.  Mutualism
 Amensalism
 Commensalism
 Parasitism
(with examples)

3.  MUTUALISM is the way
two organisms of different spe
cies exist in a relationship in
which each individual benefits
from the activity of the other.
 Mutualistic interactions are
vital for
terrestrial ecosystems as more
than 48% of land plants rely
on mycorrhizal relationships
with fungi to provide them
with inorganic compounds and
trace elements.
Mycorrhizal association is an
example for mutualism

4. Types of relationships
 Service-resource relationships
Pollination in which nectar or pollen (food
resources) are traded for pollen dispersal (a
service) or ant protection of aphids, where the
aphids trade sugar-rich honeydew in return for
defense against predators such as ladybugs.
 Service-service relationships
In the relationship between sea
anemones and anemone fish, the anemones
provide the fish with protection from predators
and the fish defend the anemones
against butterflyfish, which eat anemones.
 Humans
Humans are involved in mutualism with
other species. Their gut flora is essential for
efficient digestion.
Some relationships between humans
and domesticated animals and plants are to
different degrees of mutualism. For example,
agricultural varieties of maize provide food for
humans and are unable to reproduce without
human intervention because the leafy sheath does
not fall open, and the seed head does not shatter
to scatter the seeds naturally.
Pollination (service – resource)
Sea anemone and anemone
fish (service – service)

5.  Amensalism is the type of relationship that exists
where one species is inhibited or completely
obliterated and one is unaffected by the other.
 There are two types of Amensalism; competition
and antibiosis.
 Competition is where a larger or stronger organism
deprives a smaller or weaker one from a resource.
 Antibiosis occurs when one organism is damaged or
killed by another through a chemical secretion.

6.  Competition: A sapling growing
under the shadow of a mature tree:
 The mature tree can rob the
sapling of necessary sunlight and,
if the mature tree is very large, it
can take up rainwater and deplete
soil nutrients.
 Throughout the process, the
mature tree is unaffected by the
sapling. Indeed, if the sapling
dies, the mature tree gains
nutrients from the decaying
sapling.
 Antibiosis: Juglans nigra (black
walnut), secretes juglone, a
substance which destroys many
herbaceous plants within its root
zone.
Competition between trees and saplings
Antibiosis in Black walnut

7.  In commensalism, one organism benefits from the
relationship while the other species involved neither
benefits nor is harmed.
 The unharmed organism is unaware of what is
happening, or chooses to ignore it.
 The organism benefitting is often gaining food or
shelter.
 The benefits for one organism can be in a variety of
forms, including food, shelter, transportation and
seed dispersal.

8. Commensalisms vary in strength and duration from
intimate, long - lived symbioses to brief, weak
interactions through intermediaries.
 Phoresy
Phoresy is one animal attached to
another exclusively for transport,
mainly arthropods, examples of which
are mites on insects (such
as beetles, flies or bees), millipedes on birds,
etc.
 Inquilinism
Inquilinism is the use of a second
organism for permanent housing. Examples
are epiphytic plants (such as many orchids)
that grow on trees, or birds that live in holes
in trees.
 Metabiosis
Metabiosis is a more indirect
dependency, in which one organism creates or
prepares a suitable environment for a second.
Examples include maggots, which feast and
develop on corpses; and hermit crabs, which
use gastropod shells to protect their bodies.
Phoretic mites on Sexton beetle
Inquilinism in birds
Hermit crab

9.  Parasitism is a non-mutual relationship
between species, where one species, the parasite,
benefits at the expense of the other, the host.
 Parasites typically do not kill their host, are
generally much smaller than their host, and often
live in or on their host for an extended period.

10.  Parasites reduce hosts’ biological
fitness by general or
specialized pathology, from impairment
of secondary sex characteristics, to the
modification of host behavior.
 Parasites increase their own fitness by
exploiting hosts for resources necessary
for their survival, in
particular transmission.
 Although parasitism often applies
unambiguously, it is part of a continuum
of types of interactions between species,
grading via parasitoidy into predation.
 Examples include interactions
between vertebrate hosts
and tapeworms, flukes,
the Plasmodium species, and fleas.
Tapeworm in mammalian gut
Broodal parasitism