Elementary Concepts of Sociobiology PDF

Sociobiology SOCIAL EVOLUTION: ELEMENTARY CONCEPTS OF SOCIOBIOLOGY  Basic Definitions  Sociobiology: is the systematic study of the biological basis of all social behavior” (Wilson, 1975, 4).  the scientific study of the biological (especially ecological and ev...

Sociobiology SOCIAL EVOLUTION: ELEMENTARY CONCEPTS OF SOCIOBIOLOGY  Basic Definitions  Sociobiology: is the systematic study of the biological basis of all social behavior” (Wilson, 1975, 4).  the scientific study of the biological (especially ecological and evolutionary) aspects of social behavior in animals and humans.  Society: a group of individuals belonging to the same species and organized in a cooperative manner.  Altmann (1965) has expressed the aspect of society as: "A society is an aggregation of socially intercommunicating, conspecific individuals that is bounded by frontiers of far less frequent communication."  Basic Definitions  Aggregation: a group of individuals of the same species, comprised of more than just a mated pair or a family, gathered in the same place but not internally organized or engaged in cooperative behavior.  Winter congregations of rattlesnakes and ladybird beetles, for example, may provide superior protection for their members, but unless they are organized by some behavior other than mutual attraction they are better classified as aggregations than as true societies.  Basic Definitions  Colony: in strict biological usage, a society of organisms which are highly integrated, either by physical union of the bodies or by division into specialized zooids or castes, or by both.  In the vernacular and even in some technical descriptions, a colony can mean almost any group of organisms, especially if they are fixed in one locality.  In sociobiology, however, the word is best restricted to the societies of social insects, together with the tightly integrated masses of sponges, siphonophores, bryozoans, and other "colonial" invertebrates.  Basic Definitions  Individual: any physically distinct organism.  Group: a set of organisms belonging to the same species that remain together for any period of time while interacting with one another to a much greater degree than with other conspecific organisms.  The word group is thus used with the greatest flexibility to designate any aggregation or kind of society or subset of a society.  Population: a set of organisms belonging to the same species and occupying a clearly delimited area at the same time.  In the case of sexually reproducing organisms, the population is a geographically delimited set of organisms capable of freely interbreeding with one another under natural conditions.  The special population used by model builders is the deme, the smallest local set of organisms within which interbreeding occurs freely.  Basic Definitions  In sexually reproducing forms, including the vast majority of social organisms,  A species is a population or set of populations within which the individuals are capable of freely interbreeding under natural conditions.  By definition the members of the species do not interbreed freely with those of other species , however closely related they may be genetically.  A geographic race or subspecies is population that differs significantly from other populations belonging to the same species.  Subspecies are separated from other subspecies by distance and geographic barriers that prevent the exchange of individuals.  Basic Definitions  What is the relation between the population and the society?  The distinction between the two categories is essentially as follows : the population is bounded by a zone of sharply reduced gene flow, while the society is bounded by a zone of sharply reduced communication. Often the two zones are the same, since social bonds tend to promote gene flow among the members of the society to the exclusion of outsiders.  Basic Definitions  A detailed field studies by Stuart and Jeanne Altmann (1970) on the yellow baboons (Papio cynocephalus ) of Amboseli show that in this species the society and the deme are essentially the same thing.  The baboons are internally organized by dominance hierarchies and are usually hostile toward outsiders.  Gene exchange occurs between troops by the emigration from one to another of subordinate males, who typically leave their home troop after the loss of a fight or during competition for estrous females. Amboseli National Park is in southern Kenya. It’s known for its large elephant herds and views of immense Mount Kilimanjaro, across the border in Tanzania. Varied wildlife includes giraffes, zebras, cheetahs and hundreds of bird species.  Basic Definitions  Communication: action on the part of one organism (or cell) that alters the probability pattern of behavior in another organism (or cell) in an adaptive fashion.  Coordination: interaction among units o f a group such that the overall effort of the group is divided among the units without leadership being assumed by any one of them.  Examples of Coordination: fish school Encirclement of prey by a pride of lions  Basic Definitions  Hierarchy: in ordinary sociobiological usage, the dominance of one member of a group over another, as measured by superiority in aggressive encounters and order of access to food, mates, resting sites, and other objects promoting survivorship and reproductive fitness.  Basic Definitions  Regulation: in biology, the coordination of units to achieve the maintenance of one or more physical or biological variables at a constant level.  The result of regulation is termed homeostasis.  At a higher level, social insects display marked homeostasis in the regulation of their own colony populations, caste proportions, and nest environment.  The Multiplier Effect  Social organization is the class of phenotypes furthest removed from the genes.  It is derived jointly from the behavior of individuals and the demographic properties of the population.  A small evolutionary change in the behavior pattern of individuals can be amplified into a major social effect by the expanding upward distribution of the change into multiple facets of social life. Small differences at the level of genotype can explode up into large differences at the level of phenotype  The Multiplier Effect  The differing social organizations of the related olive baboon (Papio anubis ) and hamadryas baboon (P. hamadryas ).  These two species are so close genetically that they interbreed extensively where their ranges overlap and could reasonably be classified as no more than subspecies. olive baboon hamadryas baboon  The Multiplier Effect  The hamadryas male is distinguished by its proprietary attitude toward females, which is total and permanent.  Whereas the olive male attempts to appropriate females only around the time of their estrus.  This apparently genetic difference is only one of degree, and would scarcely be noticeable.  Yet this trait alone is enough to account for profound differences in social structure, affecting the size of the troops, the relationship of troops to one another, and the relationship of males within each troop.