Lecture Outline - Chapter 31

31.1. Genetic Basis of Behavior (p. 628)

1. Experiments can often determine if behaviors have a genetic basis:
   • a. Peach-faced lovebird cuts and transports short materials to nest via its feathers; Fisher's lovebird transports heavier materials to nest using its beak; and when two species are mated to form hybrid, hybrid cuts larger strips and fails to carry them in feathers, eventually using beak in confused manner.
   • b. Aquatic garter snakes prefer fish and frogs, rarely eat slugs; coastal garter snakes eat slugs; hybrids have intermediate taste for slugs.
   • c. Counting the number of "tongue-flicks" by snakes revealed difference was in nervous system physiology and not lack of sensitivity to odors.
2. Aplysia experiments show both nervous system and endocrine system control body responses.
   • a. Egg-laying behavior of Aplysia snail involves sequence of movements.
   • b. After copulation, snail extrudes long string of egg cases.
   • c. Takes egg case string in mouth, covers it with mucus, waves head to wind string to attach it to rocks, etc.
   • d. Scientists isolated egg-laying hormone (ELH); triggers egg-laying even without mating.
   • e. ELH is 36-amino acid protein; diffuses into circulatory system causing smooth muscle contractions resulting in egg expulsion.
   • f. Using recombinant DNA techniques, researchers isolated ELH gene; gene product is protein with 271 amino acids that cleaves into 11 products including ELH.

1. Fixed Action Patterns (FAPs)
   • a. FAPs are defined as behaviors always performed the same way each time.
   • b. FAPs described as elicited by sign stimulus, a cue that sets behavior in motion.
   • c. Standard example is baby's smile when face-sized mask with eyes is brought near.
   • d. But many FAPs appear to develop with practice.
   • e. Laughing gull chick's begging behavior is directed toward parent's beak; apparent set behavior may involve learning because parent may sway its beak to stimulate begging, encourage chick to eat regurgitated food. (Fig. 31.3)
2. Learning is defined as a durable change in behavior brought about by experience.
   • a. Repeat of gull begging-behavior experiment with chicks hatched in dark incubator found an increase in accurate pecking by chicks from 30% to over 75% after two days among nestmates.
3. Operant conditioning is the gradual strengthening of stimulus-response connections.
   • a. Used by animal trainers; animal is rewarded for making a proper choice.
   • b. Used by B.F. Skinner to train mice to press levers for food; train pigeons to play ping-pong, etc.
4. Imprinting is behavior where chicks, ducklings, etc. follow first moving object they see after hatching.
   • a. Englishman Douglas Spalding was first to observe imprinting.
   • b. Konrad Lorenz investigated imprinting in detail.
     • i. Critical period of time during which imprinting is possible is first two days for goslings.
     • ii. Causes male birds to court correct species (looks like mother).
   • c. Complicated by experiments by Eckhard Hess showing mallard ducklings imprinted on humans switch to mallard mother who is "clucking" while imprinting her own young.
5. Birds Which Learn to Sing
   • a. Birds raised in isolation sing an incomplete song that is coarse and undeveloped.
   • b. Birds must hear their species of song to refine the correct dialect within a window of learning when 10-50 days old.
   • c. Birds can partially learn song of even a different species, but sensitive period shows critical neuron development "window."

1. Because genes influence development of behavior, behavioral traits evolve.
2. In birds and mammals, reproductive strategies and selection are different.
   • a. Males with high numbers of sperm can father many offspring; must compete for females.
   • b. Females with fewer eggs are in position to select males; this is sexual selection.
3. Females Choose
   • a. Courtship rituals prepare sexes for mating by helping each recognize mate and allowing female to choose.
   • b. Study of bowerbirds tested two hypotheses (Fig. 31.1)
     • i. Good genes hypothesis: females choose mates on basis of traits that improve survival.
     • ii. Run-away hypothesis: females choose mates on basis of traits that make them attractive to females.
     • iii. Results showed females selected more aggressive and vigorous males that also kept bowers in good condition, slightly supporting both hypotheses.
   • c. Polygynous and monogamous birds.
     • A. Male raggiana bird:
       • i. Is polygynous-has more than one mate.
       • ii. Does not help raise offspring.
       • iii. Rich food supply of nutritious, complex fruits may allow luxury of inseminating many females with only females rearing young.
       • iv. Lekking is method males attract the wide-ranging females.
     • B. Related trumpet manucode:
       • i. Is monogamous-the pair bonds perhaps for life.
       • ii. Feeds on figs which are prevalent but not as nutritious as complex fruits.
       • iii. Both sexes are needed to successfully raise the young.
4. Males compete but positive effects must outweigh negative for reproductive success.
5. Baboons have a Dominance Hierarchy.
   • a. Baboons live together in troops.
   • b. Resources are limited.
   • c. Baboons are dimorphic ("two forms")
     • i. Males are larger than females.
     • ii. Males determine troop movements, defend if attacked.
   • d. Dominance hierarchy determines ranking.
     • i. Higher ranked individual have access to greater resources.
     • ii. Dominance decided by confrontations; one animal gives way to another.
   • e. Larger size and willingness of dominant male baboons to fight is a benefit.
     • i. They eat first, but their larger size means that they need more to eat, which could be a problem in lean times.
     • ii. Their willingness to fight could lead to injuries and even death.
     • iii. But they get to mate with females when they are fertile; researchers counted copulations and found they monopolize estrous females when females are most fertile.
6. Red Deer Stake Out a Territory
   • a. Territoriality is defensive behavior to defend a territory.
   • b. Vocalizations and displays may defend a territory without fighting; male song birds sing to define a territory.
   • c. Male red deer on Scottish Island of Rhum
     • i. One male becomes harem master by locking antlers, pushing other males.
     • ii. Secures harem of group of female deer.
     • iii. Studies by Clutton-Brock reveal male can father only two dozen because he is at peak of fighting ability for short time.
     • iv. Because they must grow faster to be large to fight, lack of fat makes them more likely to starve in bad times.

1. Animal social behavior ranges from solitary to occasional cooperation to societies with organized cooperation extending over generations; usually requires communication.
2. Communication is Varied (p. 635)
   • a. Communication is any action by a sender that influences behavior of a receiver.
   • b. When sender and receiver are same species, signals benefit both.
   • c. Signals received by different species can cue defensive behavior, etc.
3. Chemical Communication
   • a. Works both night and day.
   • b. Pheromones are chemical signals passed between members of same species.
   • c. Female moths secrete unique pheromone to attract males that are downwind.
   • d. Cheetahs and other cats mark territory by depositing urine, feces, and anal gland secretions at boundaries. (Fig. 31.7)
4. Auditory Communication (Fig. 31.8)
   • a. Faster than chemical communication.
   • b. Can be sent and received in dark.
   • c. Can be modified by loudness, pattern, duration, and repetition.
   • d. Birds have various calls for courting, distress, marking territory.
   • e. Humpback whales have six basic songs.
   • f. Language is ultimate auditory communication.
     • i. Although chimpanzees can be taught to use artificial language, they never progress beyond level of a two-year-old child.
     • ii. Chimpanzees appear to mimic their teachers and not understand cognitive use of a language.
5. Visual Communication
   • a. Mostly used by species active during daytime.
   • b. Postures may prevent fighting that might result in reduced fitness.
   • c. Male baboon displays establish dominance and keeps peace. (Fig. 31.6)
   • d. Male bird plumage and courtship dances attract mates. (Fig. 31.5)
6. Tactile Communication
   • a. Occurs when one animal touches another.
   • b. Example: baby gulls peck at parent's beak for feeding. (Fig. 31.3)
   • c. Grooming helps cement social bonds within a group of primates.
   • d. Waggle dance in bees gives tactile and auditory information for distance and direction to a food source. (Fig. 31.9)

1. Sociobiology applies evolutionary biology to study of social behavior of animals, including humans.
2. Group living can provide benefits of: detecting or avoiding predators, rearing offspring, finding food.
3. Pair bonding provides benefits: male and female working together can rear more young, birds and primate troops share information about food sources, and lions working together can capture larger prey.
4. Group living can have disadvantages:
   • a. Crowding can cause disputes for feeding and sleeping sites.
   • b. Dominant females can rear sons likely to leave more offspring, but subordinate females may not have enough resources to rear larger sons.
   • c. Living in close groups increases transmission of illness and parasites.
5. Altruism Versus Self-Interest (p. 637)
   • a. Altruism is behavior benefiting reproductive success of another member of same species but potentially decreasing lifetime of altruist.
   • b. Queen ant or bee provides example.
     • i. Queen and workers are diploid; male drones are haploid.
     • ii. Workers are formed from haploid drone sperm plus mixed half set of queen's diploid genes from normal egg production.
     • iii. Therefore, sibling workers have three-fourths of their genes in common.
     • iv. If workers were fertile, their offspring would only carry half their genes; by helping sibling workers and queen, they pass more of their genes to next generation through these relatives.
     • v. Inclusive fitness of individual includes personal reproduction and reproduction of relatives.
     • vi. Allows ants and bees to produce specialized non-reproductive castes of soldiers, etc., to protect hive or nest but not reproduce.
   • c. Even with normal reproduction where siblings share 50% of genes, risky behavior to protect siblings or nieces and nephews is worthwhile in preserving genes in next generation.
   • d. Because males in a chimpanzee group are all related, they do not interfere with multiple matings of females since this also promotes survival of their genes.
6. Helpers at the Nest
   • a. Commonly observed that more young survive with family helpers.
     • i. Florida scrub jays double their fledgling survival if first clutch stays on to help rear second generation.
     • ii. An African jackal pair averaged 1.4 pups; with help of family group, reared 3.6 pups. (Fig. 31.10)
     • iii. African green wood-hoopoes have one reproductive pair and 16 family members helping; protective roost holes are rare; non-reproductives help on "stand by" in case reproductive dies.
   • b. Three factors:
     • i. Direct selection operates when breeding pair has own offspring.
     • ii. Indirect selection operates when helpers assist parents and siblings to raise offspring.
     • iii. Reciprocity occurs when unrelated individual aids another with some chance of being repaid in future, such as inheriting territory.