This document discusses pheromones, which are chemicals secreted by organisms that trigger social responses in others of the same species. It defines pheromones and outlines their evolution from compounds with other uses to specialized signals. The document then describes several types of pheromones used for aggregation, alarm, reproduction, territory marking, and more. It also discusses the secretory organs that produce pheromones and their role in communication across the animal kingdom.

1. PRESENTATION
ON
PHEROMONE
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2. INTRODUCTION
 The term “pheromone” was first introduced by Peter Karlson
and Martin Luscher in 1959.
 It is Greek origin in which phero “ to carry or transfer” and
hormone “to stimulate”.
 “A pheromones is secreted or excreted chemical factor that
triggers a social response in members of the same species”.
 Pheromones are the chemicals capable of acting outside the
body of the secreting individual to impact the behavior of the
receiving individual.
 Pheromones are used from basic unicellular prokaryotes to
complex multicellular eukaryotes.

3. EVOLUTION OF PHEROMONE
 Chemical senses are the oldest, shared by all organisms
including bacteria, so animals are pre-adapted to detect
chemical signals in the environment.
 Signals are derived from movements, body parts or molecules
already in use and are subsequently changed in the course of
evolution to enhance their signal function.
 Pheromones evolve from compounds originally having other
uses or significance.
 There is selection for functional signal features such as
longevity and specificity.
 There is also evolution in the senses and response of the
receiver
 Due to which pheromones are became the mostly acceptable
way of communication among animals.

5. Types of pheromones
1. Aggregation pheromone:
• Aggregation means group or mass of individual
• It’s function in defense against predators, mate selection,
and overcoming host resistance by mass attack.
• It have been found in insects, animals.

6. 2. Alarm pheromones:
• Some species release a volatile substance when attacked by
a predator that can trigger flight or aggregation. For
example- aphids, ants, bees, termites.

7. 3. Releaser pheromones:
• releaser pheromones are pheromones the cause an
alteration in the behaviour of the recipient.
For example- some organisms use powerful attractant
molecules to attract mates from a distance of two miles
or more.

8. 4. Signal pheromones:
• Signal pheromones cause short-term changes, such as
the neurotransmitter release that activates a response.
For instance, GnRH molecule function as a
neurotransmitters in rats to elicit lordosis behaviour.

9. 5. Primer pheromones:
• Primer pheromones trigger a change of development events
it is differ from all the other pheromones, which trigger a
change in behaviour.
• For example- primer pheromones include stimulation of
sperm production in fish, termites cast determination, locust
development rates, and menstrual cycles in human and other
mammals.
6. Epideictic pheromones:
• Epideictic pheromones are different from territory
pheromones
• For examples- in insects, female who lay their eggs in fruits
deposit these mysterious substance in the vicinity of the
clutch to signal to other females of the same species they
should clutch elsewhere.

10. 7. Territorial pheromones:
• Territorial pheromones mark the boundaries of an
organism’s territory.
• For example- in some animals, these hormones are present
in urine which they deposit on landmarks serving to mark
the perimeter of the claimed territory.

11. 8. Trail pheromones:
• Trail pheromones are common in social insects.
• For example- ants mark their paths with these pheromones,
which are volatile hydrocarbons. Certain ants lay down an
initial trial of pheromones as they return to the nest with
food. This trial attracts other ants and serves as a guide.

12. 9. Information pheromones:
• Information pheromones are indicative of an animal’s identity
or territory. For example- dogs and cats deposit chemicals in
and around their territory, which then serve as an indicator
for other member so the species about the presence of the
occupant in that territory
10. Sex pheromones:
• In animals, sex pheromones indicate the availability of the
female for breeding, male animals may also emit pheromones
that convey information about there species and genotype
• At the microscopic level, a number of bacterial species release
specific chemical into the surrounding media to induce the
“competent” state in neighboring bacteria.

13. Secretory organ for pheromones
 The independent and multiple evolution of pheromones is
illustrated only by the diversity of compounds produced but
also by the enormous variety of specialized secretory glands.
 In mammals there are secretory glands in species-specific
positions such as the flanks, around the eye, around the
genitals and anus. The equivalents in male Lepidoptera are a
profusion of specialized brushes, fans and other structures on
the wings, legs and abdomen for exposing the pheromones
produced in associates glands.

14. production
 The signaler itself synthesizes and secretes most pheromones,
some components of pheromones may be collected or gained
in other way.
 For example- the completer aggregation pheromone for some
bark beetle species includes components produced by host
tree as well as components produced by symbiotic bacteria in
the beetle gut.
 Many mammals pheromones are produced by the action of
bacterial fermentation, for example of fatty acid secretion in
the anal glands of foxes.

15. specificity
 There is a need for privacy in communication and alarm
pheromones are often not species specific.
 For gaining specificity in pheromones signals.
 One is by the evolution of a large unique molecule, peptide
pheromone. Eg: two related species of newt having difference
of two amino acids in their decapeptide pheromones.
 More commonly, specificity is gained largely by using a
unique blend of relatively simple compound as a multi-
component pheromone. Eg: female sex pheromones in moths
usually consist of five to six fatty acids or their derivatives.

16. Functional signal design

17. uses
 Non-human :
• Biological pest control, Pheromones trap for trapping pest for
monitoring purposes, to control the population by creating
confusion, to disrupt mating, etc.
 Humans:
• While human are highly dependent on visual eyes, there is an
inherent difficulty in studying human pheromones because
of the need for cleanliness and odourlessness. The focus of
experiment on human pheromones are axillary steroids,
vaginal aliphatic acid, and stimulators of the vomeronasal
organ.
 Avoidance of interbreeding in close relatives and to minimize
deleterious inbreeding. Like in , mice.

18. limits
 Size of organisms.
 Diffusion rate of pheromones.
 Sensible concentration.
conclusion
 Across the animal kingdom, more interaction are mediated by
pheromones than by any other kind of signal. Evolution of
pheromones very likely because there is selection for any
odour cue that increases reproductive success or survival.
Pheromones perhaps provide the supreme honest signals.
Given the ubiquity of chemical communication among
animals, chemical cues are likely to emerge as one of the key
criteria animals use for choice of mate.