Chapter 51 ~Animal Behavior

Behavior-what an animal does and why it does it. Ethology~ study of animal behavior Behavior results from both genes and environmental factors. Causation: •proximate~ physiological & genetic mechanisms of behavior •ultimate~ evolutionary significance of behavior

Observation of Magnolia Warbler Proximate Breeds in spring and early summer Hypothesis-effect of increased day length on photoreceptors brings on breeding. Stimulus results in neural and hormonal changes that induce this behavior. Ultimate Why did natural selection favor this behavior? Hypothesis-breeding is most productive or adaptive at this time. Food more plentiful.

Innate Behavior Developmentally fixed Often attributed to genetic programming without environmental influence. Baby birds opening mouth for food Key point-is the range of environmental differences among individuals does not appear to alter the behavior.

Innate Behavior Fixed action pattern (FAP)~ sequence of acts; unchangeable; carried to completion Sign stimulus ~these patterns are triggered by an external sensory stimulus Ex: 3-spined stickleback (Tinbergen ‘73 Nobel) Utilizes its color vision to identify red-undersided males that try to invade its territory.

Foraging Mechanisms animals use to recognize, search for, and capture food items. Optimal foraging theory Feeding costs verses feeding benefits.

Behavioral ecology concentrates on ultimate hypotheses Animals utilize their genetic variation to express behaviors that optimize their fitness Natural selection favors behaviors that enhance survival and reproductive success.

Learning-experience based modification of behavior Maturation~ behavior due to developing physiological changes. Habituation~ loss of responsiveness to stimuli that convey no information; simple learning Imprinting~ limited learning within a specific time period •critical period (Lorenz, ‘73 Nobel)

Associative Learning Connecting two different stimuli Ivan Pavlov-Classical conditioning Involves associating arbitrary stimuli with either a reward or punishment. Skinner-Operant Conditioning-trial and error Induced manipulation of levers by rats after awarding them with food.

Associative Learning •classical conditioning~ Pavlov’s dogs •operant conditioning (trial and error)~ “Skinner’s box”

Social behavior Sociobiology~ evolutionary theory applied to social behavior (Hamilton) Agonistic behavior~ contest behavior determining access to resources Dominance hierarchy~ linear “pecking order” Territoriality~ an area an individual defends excluding others Mating systems: •promiscuous~ no strong pair bonds •monogamous~ one male/one female •polygamous~ one with many •polygyny~ one male/many females •polyandry~ one female/many males

Agnostic Behavior Competition for a resource Sometimes simply ritual Signifies intent but causes no harm Causes social hierarchies to develop in some animals Dominance hierarchy Territoriality

Mating behavior Parental investment-time and resources required to produce an offspring. Female usually has higher parental investment-eggs more costly to produce Sexual selection-competition among males for the female to choice him. Females usually care for young. Paternity not always know. Very few have only male paternal care.

Altruistic behavior-reducing individual fitness to increase that of another Inclusive fitness~ total effect an individual has on proliferating its genes by its own offspring and aid to close relatives Coefficient of relatedness~ measures inclusive fitness by proportion of genes that are identical because of common ancestors Kin selection~ aiding related individuals altruistically can result in more identical genes Reciprocal altruism~ exchange of aid; humans?