Adaptiveness of Behavior

Chapter 43

I. What are the Causes of Behavior?A. two levels of causation

1. proximate causationa. immediate basis of behavior (“how”)b. includes learned behaviors; anatomy and physiology

2. ultimate causationa. evolutionary basis of behavior (“why”)b. includes innate and instinctive behaviors

B. behavioral ecology1. impact of behavior on an organism’s life 2. uses both kinds of causation and many variables are involved3. habitat selection

a. why do animals live where they do?b. how is habitat chosen – genetics or learning?

4. foraging behavior a. why do animals forage where they do?b. generalists vs. specialists

• opportunists vs. extreme specialistsc. efficiency of foraging

• maximize gain and minimize expenditure

Fig. 43.13 Foraging for food

II. Biological ClocksA. innate mechanisms that allow an org. to perceive lapse & flow of time B. biorhythms (cycles)

1. behaviors associated with biol. clocks2. annual

a. yearly cycles, usually based on the seasonsb. most fundamental life activities are annual cycles

3. lunara. based on phases of moon causing the tidesb. Important for intertidal organisms

4. circadiana. daily, day-night cycles b. diurnal vs. nocturnal vs. crepuscularc. can be influenced by photoperiod (day-length)

5. organ, physiological, hormonal, cellular cyclesIII. Orientation and Navigation

A. navigation1. directional sense that allows orgs. to make way back to territory 2. compass sense (general direction) vs. map sense (specific location)

• often coupled to biol. clocks time-direction mechanismB. orientation

• navigation around env. obstacles

C. migration1. seasonal movement of a sp. from one geographic location to another2. vast distances3. between breeding & non-breeding (wintering) grounds4. high E and risk5. occurs in many species6. some sp. only migrate if conditions are very harsh7. navigation cues

a. sun (day migrators)b. stars (night migrators)c. earth's magnetic fieldd. geographical cues (mountains, rivers, etc.)e. memory, experience (learning), biorhythmsf. group cohesion (ind. working together)

8. migration is triggered by:1. physiological cues (esp., changing hormone levels)2. changing photoperiod and env. temperature

• migratory sp. get “restless” just prior to migration9. combination of genetics and experience

General Cues

Specific Cues

Fig. 43.6 Starling migratory experiment, showing the combined effect of genetics and learning

IV. Animal CommunicationA. any behavior produced by one org. and received by another responseB. enhances survival and reproduction reproductive enabling deviceC. direct vs. indirect

• enhancing one’s own reproductive success vs. enhancing success of offspringD. modes of communication

1. each has advantages and disadvantages2. visual

a. color, posture, shape, movement b. graded displays

Fig. 43.10 Fireflies using visual communication. Each number represents the male flash pattern of a different species. The patterns are a behavioral reproductive isolating mechanism.

Fig. 43.9 Male baboon displaying a full visual

threat display.

3. vocala. frequency, amplitude, durationb. seismic communication

• produced in some way other than vocal apparatus

c. vocal repertoire• sp. full range of vocal comm.

The repertoire of a songbird

Fig. 43.8 Vocal communication in vervet monkeys. The monkeys give different alarm calls according to whether a troop member sights an eagle or leopard.

4. chemicala. pheromonesb. most basic of all comm. formsc. can produce stereotyped behaviors

• always performed in same way5. tactile

• touch or very close proximityV. Social Behavior

A. behavior of orgs. in groupsB. agonistic behavior

1. behaviors used to resolve conflict2. intraspecific vs. interspecific3. territoriality

• behaviors associated with defending territory

C. fighting • usually ritualized

o not to death

Fig. 43.15 Ritualized competition among elk

Fig. 43.7 Chemical communication with a pheromone. A male cheetah spraying

urine to mark his territory.

C. cooperation• species or individuals work together for mutual benefit

D. mating behavior1. may include sexual dimorphism

• visual and/or behavioral differences between males and females2. often involves species-specific courtship rituals and displays

• males advertise/display for females females choose mateso female-choice

Fig. 43.14 Sexual dimorphism in Hamadryas baboons. The male is silver-white and twice the size of the brown females.

Female warblers prefer males with large song repertoires.

3. several modes of communication used4. social dominance hierarchies often play a role

• males compete among themselves for dominance and position o winners have greatest access to females mate with females

male competition

Female choice and male dominance among baboons.

E. symbiosis1. two or more species living closely together 2. mutualism

• both organisms benefit from relationship 3. commensalism

• one organism benefits, the other is unaffected 4. parasitism

a. one organism benefits, the other is harmedb. host vs. parasitec. endoparasites vs. ectoparasites

F. altruism1. any action that benefits another individual at one’s own expense2. kin selection

• tendency to help relatives at one’s own expense3. reciprocal altruism

• “I’ll scratch your back, if you scratch mine”VI. Sociobiology (E.O. Wilson)

A. applies evolutionary principles to study of social behaviorB. adaptive basis for animals to live together in groups

1. group foraging2. group protection (“selfish herd” effect)3. increased vigilance4. reproductive coordination