pheromones bkk
TRANSCRIPT
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.
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.
Types of pheromones1. 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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
Functional signal design
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.
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.