Social Behavior (L17) T3 Flashcards
Sociobiology
The systematic study of the biological basis of all social behavior.
Levels of sociobiology
- Individual
- Population: A set of organisms of the same species and occupying a clearly delimited area at the same time.
- Aggregation: Loosely organized, non-interacting set of individuals of the same species.
- Group: Set of individuals of the same species together while interacting with each other more then with other conspecific organisms.
- Society: Set of individuals in the same species organized in a cooperative manner.
- Colony: Society of organisms highly integrated by physical union of bodies or division into specialized castes.
Distinction between a population and a society
Population: Bounded by a zone of sharply reduced gene flow.
Society: Bounded by a zone of sharply reduced communication.
4 Major BENEFITS of sociality
- Defense: detection/repulsion of enemies.
- Foraging: for large game or clumped ephemeral resources.
- Territoriality: defense of limited resources (e.g. space, food) from other conspecific groups.
- Care of offspring: communal feeding and protection.
4 Major COSTS of sociality
- Competition: within group resources (e.g. food, males, nest).
- Diseases: by contagious pathogens and parasites.
- Exploitation of parental care by conspecifics.
- Killing of offspring: by conspecifics.
Individual selection
Selection that operates on the individual. Natural selection operates MOST strongly at this level.
Group Selection
Selection that operates on two or more members of a lineage group as a unit.
- Interdemic selection
- Kin Selection
Interdemic Selection
Selection of entire breeding populations (demes) as the basic unit.
The major problem is that cheaters always prosper, with higher fitness than self-sacrificing individuals.
3 conditions that facilitate group selection
- Variability greater among populations than among individuals of a population.
- Populations semi-isolated with no gene flow.
- Extinction rates higher for groups than individuals
Kin Selection
- Direct selection: Selection operates on individual reproductive success.
- Selection operates on the reproductive success of relatives.
Social interactions between members of the SAME specifics.
Cooperation: Behavior that is mutually and simultaneously beneficial behavior. It is very common among animals.
Selfishness: Behavior that benefits an individual at the expense of one or more other individuals of the same species. Example would be a gull kleptoparasitizing food from another gull.
Altruism: Self-sacrificing behavior performed for the benefit of other individuals. Bees who commit suicide for the good of the hive.
Reciprocity or Reciprocal altruism: Trading of altruistic acts by individuals different times. Ex: One animal assists another with the expectation of the favor being returned on a later occasion.
Spite: Behavior that lowers fitness of both perpetrator and recipient. Very difficult to distinguish from selfishness.
How can a signaler benefit from spiteful behavior? When will spiteful behavior occur?
Communicates toughness, potentially signaling to a mate that it can survive despite its losses.
Most likely to occur when intraspecific competition is intense and individuals can recognize related kin.
Helping behavior: altruism or selfishness?
Some species frequently “help” members of their own species. The ultimate goal of animals is to spread their genes. If helping aids to spread genes, then genes that promote helping will spread in the population.
Coefficient of relatedness
Probability of two individuals possessing the same allele by inheriting it from a common ancestor.
Inclusive fitness and its components
Sum of an individuals own fitness plus influence on fitness in its relatives other than direct descendants.
Components are:
- Direct fitness - fitness gained by personal reproduction
- Indirect fitness - fitness gained by acts directed toward relatives other than offspring
