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Social organization in animals
Social Behavior
“The behavior typically refers to any interaction among members of the same species as well
as members of different species except predator-prey interaction is called social behavior”.
OR
Animal social behavior, the suite of interactions that occur between two or more individual
animals, usually of the same species, when they form simple aggregations, cooperate in sexual or
parental behavior, engage in disputes over territory and access to mates, or simply communicate
across space.
Social organization:
Social organization is a pattern of relationships between and among individuals and social groups.
The term social organization includes: Physical structure: the size of the group and its
composition with respect to age, sex and degrees of relatedness of group member and Social
structure: all the relationships among individuals in the group. Normally
six major forms of social behavior are found in animals such as;
1. Living in groups or social grouping:
It is the most widely recognized forms of social behavior. Animal population often organized
in groups. A group of animals may form an aggregation for some simple purpose like feeding,
drinking, mating etc. Several Drosophila flies live on a piece of rotting fruit. It is an example
of an aggregation. The clumping/grouping of individuals increase opportunities for
interaction. When a single female moth produces pheromones to attract male potential mates,
she is engaging in social behavior/interaction. Similarly, a male red deer (Cervus elaphus) gives
a loud roar to signal dominance and keep other males away, he is also being social.
Advantages of social grouping
There is a major benefit of belonging to a group.
It gives protection against predators. There is safety in numbers. Several group members
warn each other about an intruder.
Cooperative hunting and capturing of prey increase the feeding efficiency of predators.
Social grouping protects its members from harsh environment. They huddle together in
cold weather.
The members of the social groups help each other for finding mate and rearing of young.
Many insects have developed social grouping. These social groups have evolutionary
division of labor. Specific individuals perform specialized tasks. These tasks are
defense, food procurement and feeding of young.
Disadvantages of social grouping
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There are following disadvantages of social groupings:
Competition for resources developed. between the members of the social groups.
The diseases and parasites spread more rapidly in a group of animals.
They interfere each other for reproduction and rearing of young. The value of group
depends on the species and behaviors involved.
Agnostic Behavior, Territories, and Dominance Hierarchies
Agnostic behavior
The behavior in which one animal is aggressive or attacks another animal, the other responds
by returning the aggression or submitting is called agnostic behavior. A society of animals
maintains social structure. Agnostic behavior is lethal in rare cases. Usually the animals are not
killed or severely injured.
The males show their aggression in the form of threat displays. The aggression displays involve
signals. It warns other males of an intention to defend an area or territory. Agnostic behavior
seems antisocial. But it maintains the social order. It is important in the maintenance of
territories and dominance hierarchies.
Territory
The site defend by territorial animal by agnostic behavior is called territory of the animal. They
excluded the competing individuals from this site. Many male birds and mammals occupy a
breeding territory. A male actively defends his area against other males. He attracts a female in.
his territory and courts (mating) her without interference. Some territories. contain a food
supply. Some territories provide shelter. It protects the animal from predators and unfavorable
climate.
Dominance hierarchies (grouping)
The organization of group of animals in such a way that some members of the group have
greater access or power to the resources like food or mates than others is called dominance
hierarchies.
Some animals are present near the top of the order. They have first choice of resources. The
animals present near the bottom do not get sufficient resources.
Example:
Pecking (fight with beaks) order is an example of a dominance hierarchy.
Peck order is present in chickens in a pen. The chickens are placed together. They fight among
themselves. Finally, a linear hierarchy of dominance is formed. Higher-ranked chickens
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(dominant by power) are first to eat. They peck lower-ranked chickens (weak). Peaceful
coexistence is possible after the setting of the hierarchy. Sometimes, a bird tries to move up in
the order. Therefore, occasional fights occur.
Social Organization in Insects:
Termites, ants, bee and wasps
Live together in large well-organized colonies
Tightly integrated and genetically similar
Symbiotic communication is found among the member of colony
Communication system is called dance language
Social organization in Honey-Bee:
Live in colony containing 50,000-80,000 individual. Colony comprised of:
One fertile female or the Queen
Few hundred of male bee or drones
The rest are sterile females or Workers
Altruism (sacrifice for others)
Altruism is the behavior that is performed for the benefit of others.
Selflessness and concern for the well-being of others.
The interaction in which an individual gives up or sacrifices some of its own reproductive
potential to benefit another individual is called altruism.
In biological term, an organism is said to behave altruistically when its behavior benefits other
organisms, at a cost to itself. The costs and benefits are measured in terms of reproductive
fitness or expected number of offspring. An animal produces a large number of offspring. It
makes him successful in a biological sense. Thus it passes its genes to succeeding generations.
This animal also shares some genes with its relatives and their young. Therefore, he helps his
relative and his young. It increases his reproductive potential or output. Therefore, he helps his
relatives in their survival. Thus an individual pass more genes theoretically to the next
generation than by rearing his own young. This biological concept of altruism is not identical
to the everyday concept. In everyday practice, an action would only be called ‘altruistic’ if it
was done with the conscious intention of helping another. But in the biological sense there is
no such requirement. Indeed, some of the most interesting examples of biological altruism are
found among creatures that are not capable of conscious thought at all, e.g. insects.
Altruistic behavior is common throughout the animal kingdom, particularly in species with
complex social structures.
Examples
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1. In social insect colonies (ants, wasps, bees and termites), sterile workers devote their whole
lives to caring for the queen, constructing and protecting the nest, foraging for food, and
tending the larvae. Such behavior is altruistic: sterile workers obviously do not leave any
offspring of their ownso have personal fitness of zerobut their actions greatly assist the
reproductive efforts of the queen.
2. Altruism in Honeybee: The male drones are haploid. The female workers and queen are
diploid. It develops genetic asymmetry. Diploid workers share three fourths of their genes
with their full sisters. If they reproduced, they will share only half of their genes with
hypothetical offspring. Thus, female honeybees have more genes common with their sisters
than their offspring. The workers help their mother to produce more sisters. Thus the worker
passes more genes to the next generation by their mother. Some of their sisters become
reproductive queens.
3. Vampire bats regularly regurgitate blood and donate it to other members of their group who
have failed to feed that night, ensuring they do not starve.
4. In numerous bird species, a breeding pair receives help in raising its young from other
‘helper’ birds, who protect the nest from predators and help to feed the fledglings.
5. Vervet monkeys give alarm calls to warn fellow monkeys of the presence of predators, even
though in doing so they attract attention to themselves, increasing their personal chance of
being attacked.
6. Altruism in crows: One individual of a group of crows gives an alarm call. It warns the
other individuals of the group of a predator. This call may attract the predator to the sender
of the signal.
7. Dolphins helping others in need or a leopard caring for a baby baboon. In fact, in 2008, a
bottlenose dolphin came to the rescue of two beached whales in New Zealand and led them
into safe waters.
How altruism evolve?
Natural selection leads us to expect animals to behave in ways that increase their own chances of
survival and reproduction, not those of others. But by behaving altruistically an animal reduces its
own fitness, so should be at a selective disadvantage compared to one behaves selfishly. For
example, some members of a group of Vervet monkeys give alarm calls when they see predators,
but others do not. So, we should expect natural selection to favor those monkeys that do not give
alarm calls over those that do. But this is quite confusing. How did the alarm-calling behavior
evolve in the first place, and why has it not been eliminated by natural selection? How can the
existence of altruism be reconciled with basic Darwinian principles?
Altruism and the Levels of Selection
If selection acts exclusively at the individual level, that favors some individual organisms over
others, then altruism cannot evolve. According to the definition, behaving altruistically is
disadvantageous for the individual organism itself. However, it is possible that altruism may
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be advantageous at the group level. A group containing lots of altruists, each ready to sacrifice
their own selfish interests for the benefits of the group, may well have a survival advantage over a
group composed mainly or exclusively of selfish organisms. A process of between-group
selection may thus allow the altruistic behavior to evolve. Within each group, altruists will be
at a selective disadvantage relative to their selfish colleagues, but the fitness of the group as a
whole will be enhanced by the presence of altruists. Groups composed only or mainly of selfish
organisms go extinct, leaving behind groups containing altruists. In the example of the Vervet
monkeys, a group containing a high proportion of alarm-calling monkeys will have a survival
advantage over a group containing a lower proportion. So conceivably, the alarm-calling behavior
may evolve by between-group selection, even though within each group, selection favors monkeys
that do not give alarm calls.
Kin selection
William Hamilton (1936) proposed the idea of kin (relatives) selection. It explains that
selection act on related animals. This selection of related animals can affect the fitness of an
individual. A gene that a particular individual carries passes to the next generation through a
related animal. Therefore, the fitness of an individual is based on the genes it passes on. It is -
also based on those common genes that its relatives pass on. Therefore, altruism is a genetically
based tendency. It is passed on by the individual carrying it. But the individuals of a group must
identify its relatives for kin selection to work. It is done by small groups of primates and social
insects.
A gene which causes an individual organism to behave altruistically towards other organisms,
e.g. by sharing food with them. Organisms without the gene are selfishthey keep all their
food for themselves. However, altruists show discrimination in case of sharing their food. They
do not share with just anybody, but only with their relatives. This immediately changes things.
For relatives are genetically similarthey share genes with one another. So, when an organism
carrying the altruistic gene shares his food, there is a certain probability that the recipients of
the food will also carry copies of that gene. This means that the altruistic gene can in principle
spread by natural selection. The gene causes an organism to behave in a way which reduces its
own fitness but boosts the fitness of its relativeswho have a greater than average chance of
carrying the gene themselves. So the overall effect of the behaviour may be to increase the
number of copies of the altruistic gene found in the next generation, and thus the incidence of
the altruistic behaviour itself.
Kin selection theory predicts that animals are more likely to behave altruistically towards their
relatives than towards unrelated members of their species. Moreover, it predicts that the degree
of altruism will be greater, the closer the relationship.

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Social organization in animals Social Behavior “The behavior typically refers to any interaction among members of the same species as well as members of different species except predator-prey interaction is called social behavior”. OR Animal social behavior, the suite of interactions that occur between two or more individual animals, usually of the same species, when they form simple aggregations, cooperate in sexual or parental behavior, engage in disputes over territory and access to mates, or simply communicate across space. Social organization: Social organization is a pattern of relationships between and among individuals and social groups. The term social organization includes: Physical structure: the size of the group and its composition with respect to age, sex and degrees of relatedness of group member and Social structure: all the relationships among individuals in the group. Normally six major forms of social behavior are found in animals such as; 1. Living in groups or social grouping: It is the most widely recognized forms of social behavior. Animal population often organized in groups. A group of animals may form an aggregation for some simple purpose like feeding, drinking, mating etc. Several Drosophila flies live on a piece of rotting fruit. It is an example of an aggregation. The clumping/grouping of individuals increase opportunities for interaction. When a single female moth produces pheromones to attract male potential mates, she is engaging in social behavior/interaction. Similarly, a male red deer (Cervus elaphus) gives a loud roar to signal dominance and keep other males away, he is also being social. Advantages of social grouping There is a major benefit of belonging to a group. • It gives protection against predators. There is safety in numbers. Several group members warn each other about an intruder. • Cooperative hunting and capturing of prey increase the feeding efficiency of predators. • Social grouping protects its members from harsh environment. They huddle together in cold weather. • The members of the social groups help each other for finding mate and rearing of young. • Many insects have developed social grouping. These social groups have evolutionary division of labor. Specific individuals perform specialized tasks. These tasks are defense, food procurement and feeding of young. Disadvantages of social grouping There are following disadvantages of social groupings: • • • Competition for resources developed. between the members of the social groups. The diseases and parasites spread more rapidly in a group of animals. They interfere each other for reproduction and rearing of young. The value of group depends on the species and behaviors involved. Agnostic Behavior, Territories, and Dominance Hierarchies Agnostic behavior The behavior in which one animal is aggressive or attacks another animal, the other responds by returning the aggression or submitting is called agnostic behavior. A society of animals maintains social structure. Agnostic behavior is lethal in rare cases. Usually the animals are not killed or severely injured. The males show their aggression in the form of threat displays. The aggression displays involve signals. It warns other males of an intention to defend an area or territory. Agnostic behavior seems antisocial. But it maintains the social order. It is important in the maintenance of territories and dominance hierarchies. Territory The site defend by territorial animal by agnostic behavior is called territory of the animal. They excluded the competing individuals from this site. Many male birds and mammals occupy a breeding territory. A male actively defends his area against other males. He attracts a female in. his territory and courts (mating) her without interference. Some territories. contain a food supply. Some territories provide shelter. It protects the animal from predators and unfavorable climate. Dominance hierarchies (grouping) The organization of group of animals in such a way that some members of the group have greater access or power to the resources like food or mates than others is called dominance hierarchies. Some animals are present near the top of the order. They have first choice of resources. The animals present near the bottom do not get sufficient resources. Example: Pecking (fight with beaks) order is an example of a dominance hierarchy. Peck order is present in chickens in a pen. The chickens are placed together. They fight among themselves. Finally, a linear hierarchy of dominance is formed. Higher-ranked chickens (dominant by power) are first to eat. They peck lower-ranked chickens (weak). Peaceful coexistence is possible after the setting of the hierarchy. Sometimes, a bird tries to move up in the order. Therefore, occasional fights occur. Social Organization in Insects: • • • • • Termites, ants, bee and wasps Live together in large well-organized colonies Tightly integrated and genetically similar Symbiotic communication is found among the member of colony Communication system is called dance language Social organization in Honey-Bee: Live in colony containing 50,000-80,000 individual. Colony comprised of: • • • One fertile female or the Queen Few hundred of male bee or drones The rest are sterile females or Workers Altruism (sacrifice for others) “Altruism is the behavior that is performed for the benefit of others”. Selflessness and concern for the well-being of others. The interaction in which an individual gives up or sacrifices some of its own reproductive potential to benefit another individual is called altruism. In biological term, an organism is said to behave altruistically when its behavior benefits other organisms, at a cost to itself. The costs and benefits are measured in terms of reproductive fitness or expected number of offspring. An animal produces a large number of offspring. It makes him successful in a biological sense. Thus it passes its genes to succeeding generations. This animal also shares some genes with its relatives and their young. Therefore, he helps his relative and his young. It increases his reproductive potential or output. Therefore, he helps his relatives in their survival. Thus an individual pass more genes theoretically to the next generation than by rearing his own young. This biological concept of altruism is not identical to the everyday concept. In everyday practice, an action would only be called ‘altruistic’ if it was done with the conscious intention of helping another. But in the biological sense there is no such requirement. Indeed, some of the most interesting examples of biological altruism are found among creatures that are not capable of conscious thought at all, e.g. insects. Altruistic behavior is common throughout the animal kingdom, particularly in species with complex social structures. Examples 1. In social insect colonies (ants, wasps, bees and termites), sterile workers devote their whole lives to caring for the queen, constructing and protecting the nest, foraging for food, and tending the larvae. Such behavior is altruistic: sterile workers obviously do not leave any offspring of their own—so have personal fitness of zero—but their actions greatly assist the reproductive efforts of the queen. 2. Altruism in Honeybee: The male drones are haploid. The female workers and queen are diploid. It develops genetic asymmetry. Diploid workers share three fourths of their genes with their full sisters. If they reproduced, they will share only half of their genes with hypothetical offspring. Thus, female honeybees have more genes common with their sisters than their offspring. The workers help their mother to produce more sisters. Thus the worker passes more genes to the next generation by their mother. Some of their sisters become reproductive queens. 3. Vampire bats regularly regurgitate blood and donate it to other members of their group who have failed to feed that night, ensuring they do not starve. 4. In numerous bird species, a breeding pair receives help in raising its young from other ‘helper’ birds, who protect the nest from predators and help to feed the fledglings. 5. Vervet monkeys give alarm calls to warn fellow monkeys of the presence of predators, even though in doing so they attract attention to themselves, increasing their personal chance of being attacked. 6. Altruism in crows: One individual of a group of crows gives an alarm call. It warns the other individuals of the group of a predator. This call may attract the predator to the sender of the signal. 7. Dolphins helping others in need or a leopard caring for a baby baboon. In fact, in 2008, a bottlenose dolphin came to the rescue of two beached whales in New Zealand and led them into safe waters. How altruism evolve? Natural selection leads us to expect animals to behave in ways that increase their own chances of survival and reproduction, not those of others. But by behaving altruistically an animal reduces its own fitness, so should be at a selective disadvantage compared to one behaves selfishly. For example, some members of a group of Vervet monkeys give alarm calls when they see predators, but others do not. So, we should expect natural selection to favor those monkeys that do not give alarm calls over those that do. But this is quite confusing. How did the alarm-calling behavior evolve in the first place, and why has it not been eliminated by natural selection? How can the existence of altruism be reconciled with basic Darwinian principles? Altruism and the Levels of Selection If selection acts exclusively at the individual level, that favors some individual organisms over others, then altruism cannot evolve. According to the definition, behaving altruistically is disadvantageous for the individual organism itself. However, it is possible that altruism may be advantageous at the group level. A group containing lots of altruists, each ready to sacrifice their own selfish interests for the benefits of the group, may well have a survival advantage over a group composed mainly or exclusively of selfish organisms. “A process of between-group selection may thus allow the altruistic behavior to evolve”. Within each group, altruists will be at a selective disadvantage relative to their selfish colleagues, but the fitness of the group as a whole will be enhanced by the presence of altruists. Groups composed only or mainly of selfish organisms go extinct, leaving behind groups containing altruists. In the example of the Vervet monkeys, a group containing a high proportion of alarm-calling monkeys will have a survival advantage over a group containing a lower proportion. So conceivably, the alarm-calling behavior may evolve by between-group selection, even though within each group, selection favors monkeys that do not give alarm calls. Kin selection William Hamilton (1936—) proposed the idea of kin (relatives) selection. It explains that selection act on related animals. This selection of related animals can affect the fitness of an individual. A gene that a particular individual carries passes to the next generation through a related animal. Therefore, the fitness of an individual is based on the genes it passes on. It is also based on those common genes that its relatives pass on. Therefore, altruism is a genetically based tendency. It is passed on by the individual carrying it. But the individuals of a group must identify its relatives for kin selection to work. It is done by small groups of primates and social insects. A gene which causes an individual organism to behave altruistically towards other organisms, e.g. by sharing food with them. Organisms without the gene are selfish—they keep all their food for themselves. However, altruists show discrimination in case of sharing their food. They do not share with just anybody, but only with their relatives. This immediately changes things. For relatives are genetically similar—they share genes with one another. So, when an organism carrying the altruistic gene shares his food, there is a certain probability that the recipients of the food will also carry copies of that gene. This means that the altruistic gene can in principle spread by natural selection. The gene causes an organism to behave in a way which reduces its own fitness but boosts the fitness of its relatives—who have a greater than average chance of carrying the gene themselves. So the overall effect of the behaviour may be to increase the number of copies of the altruistic gene found in the next generation, and thus the incidence of the altruistic behaviour itself. Kin selection theory predicts that animals are more likely to behave altruistically towards their relatives than towards unrelated members of their species. Moreover, it predicts that the degree of altruism will be greater, the closer the relationship. Name: Description: ...
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