Transcript Ethology
Animal Behavior Chapter 45 Mader: Biology 8th Ed. Outline • • • • • • • • • Genetic Basis – Nature versus Nurture Learning Female Choice Male Competition Dominance Hierarchy Territoriality Communicative Behavior Sociobiology and Animal Behavior Altruism versus Self-Interest Mader: Biology 8th Ed. Genetic Basis • • Two basic types of behavioral questions: – Mechanistic – Survival Value Both recognize behavior, observable and coordinated responses to environmental stimuli, has at least a partial genetic basis. – Genes influence development of neural and hormonal mechanisms controlling behavior. Mader: Biology 8th Ed. Nature or Nurture • Nature (inherited) versus nurture (environmental) questions have been, and are still, constantly debated. – Studies on identical twins can be used to determine extent of inherited behavior. Genetically identical twins raised separately are sometimes remarkably similar. Mader: Biology 8th Ed. Behavior Undergoes Development • Some behaviors seem to be stereotyped. – Fixed Action Patterns (FAP’s) Originally assumed to be elicited by a sign stimulus. Increasingly thought to develop after practice. Mader: Biology 8th Ed. Pecking Behavior of Laughing Gull Chicks Mader: Biology 8th Ed. The Phenomenon of Learning • • Operant Conditioning – Gradual strengthening of stimulusresponse corrections. Trick-training in birds. Imprinting – Imitate behavior observed during sensitive period. Goslings follow any moving object after birth. Mader: Biology 8th Ed. The Phenomenon of Learning • Song Learning in Birds – Brain of a bird seems to be especially primed to respond to acoustical stimuli during a sensitive period. Social experience appears to have an even stronger influence over development of singing. Mader: Biology 8th Ed. Behavior Is Adaptive • Sexual selection refers to changes in females and males, often due to differential reproductive success, caused by mate choice and competition for mates. Mader: Biology 8th Ed. Female Choice • Courtship displays help males and females recognize each other for successful mating. – Good Genes Hypothesis Females benefit from selective choice by securing sperm with good genes. – Run-Away Hypothesis Females choose mates on the basis of traits that make them attractive to females. Mader: Biology 8th Ed. Male Competition • Cost-benefit analyses have been conducted to determine if the benefit of access to mating is worth the cost of competition among males. – Positive effects (benefits) must outweigh negative effects (costs) if the behavior is to continue. Mader: Biology 8th Ed. Dominance Hierarchy • Males and females have separate dominance hierarchies. – Higher-ranking individuals have greater access to resources. Baboons form temporary consort pairs with females. Males may monopolize estrous females. Or may assist females or form friendship groups to secure future matings. Mader: Biology 8th Ed. Female Choice and Baboon Male Dominance Mader: Biology 8th Ed. Territoriality • Territoriality is protecting an area against other individuals. – Red Deer Stags (males) compete for groups of hinds (females). Hinds only mate with one stag. Harem Master must be large and powerful to fight off challengers. Less body fat, thus may be more likely to starve in bad times, and have shorter life span. Mader: Biology 8th Ed. Competition Between Red Deer Stags Mader: Biology 8th Ed. Animal Societies • • Members of a society are organized in a cooperative manner that extends beyond sexual and parental behavior. Communicative Behavior – Chemical Pheromones designate chemical signals that are passed between members of the same species. Mader: Biology 8th Ed. Communicative Behavior • • Auditory – Faster than chemical communication. – Can be modified by loudness, pattern, repetition, and duration. Visual – Used by species active during the day. Contests between males make use of threat postures. Save energy by avoiding fighting. Mader: Biology 8th Ed. Communicative Behavior • Tactile – Occurs when one animal touches another. Gull chicks peck at the parent’s beak in order to induce the parent to feed them. Foraging honeybees return to the hive and perform a waggle dance that indicates the distance and direction of a food source. Mader: Biology 8th Ed. Communication Among Bees Mader: Biology 8th Ed. Sociobiology and Animal Behavior • Sociobiology applies the principles of evolutionary biology to the study of behavior in animals. – Assume individuals derive more reproductive benefits than costs from living in a society. Other advantages include predator avoidance, assistance in rearing offspring, and finding food. Mader: Biology 8th Ed. Sociobiology and Animal Behavior • Societal Disadvantages – Crowding Resource allocation. Spread of disease. Mader: Biology 8th Ed. Altruism versus Self-Interest • Altruism is behavior that involves a reduction in direct fitness that may be compensated by an increase in indirect fitness. – Inclusive Fitness includes both personal reproduction and reproduction of relatives. Genetic relatedness may underlie many/most acts of apparent altruism. Mader: Biology 8th Ed. Nest Helpers • Green Wood-hoopoes – One breeding pair per flock. Other sexually mature members may help feed and protect fledglings and protect the home territory. Helper is contributing to survival of its own kin. Helper is more likely than nonhelper to inherit parental territory. Mader: Biology 8th Ed. Migratory Behavior in Blackcap Warblers Mader: Biology 8th Ed. Feeding Behavior of Garter Snakes Mader: Biology 8th Ed. Review • • • • • • • • • Genetic Basis – Nature versus Nurture Learning Female Choice Male Competition Dominance Hierarchy Territoriality Communicative Behavior Sociobiology and Animal Behavior Altruism versus Self-Interest Mader: Biology 8th Ed. Mader: Biology 8th Ed.