Animal Behavior. How can we explain behavior? Behavior. Innate or instinctive behavior. Instinctive behavior. Instinctive behavior 11/26/2017

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1 Animal Behavior Chapter 51 How can we explain behavior? How it works physiologically Proximate answer The adaptive value of the behavior Ultimate answer So, behavioral scientists study what behavior an organism does, how it does it and why it does it. Behavior A behavior is the nervous system s response to a stimulus and is carried out by the muscular or the hormonal system Behavior is subject to natural selection Behaviors have an impact on evolution Innate or instinctive behavior Performed without having been learned Usually triggered by simple sign stimuli Response to the stimulus is a stereotyped motor program (hardwired) Instinctive behavior Sign stimuli are often nonspecific Innate releasing mechanism - a neural component of the organism that provides the motor program Fixed action pattern a sequence of behavioral acts that is essentially unchangeable and usually carried to completion once started Instinctive behavior When a goose sees an egg outside the nest (sign stimulus), it begins a repeated movement of dragging the egg with its beak and neck 1

2 Stickleback Migration and orientation Male stickleback fish will attack anything with a red underside Migration is the periodic, two-way travel of groups of animals from one location to another Orientation is the ability to follow a bearing (i.e., which way is north?) Navigation is the ability to adjust a bearing and follow it (i.e., how do I get to where I want to go, knowing that that way is north?) Orientation Animals can orient themselves using The position of the sun and their circadian clock The position of the North Star The Earth s magnetic field 2

3 Animal signals and communication Types of Communication In behavioral ecology, a signal is a behavior that causes a change in another animal s behavior Communication is the transmission and reception of signals Animals communicate using visual, chemical, tactile, and auditory signals Chemical communication: Pheromones A female moth can attract a male moth several kilometers distant Visual communication Tactile communication Auditory communication A bee returning from the field performs a dance to communicate information about the distance, direction and quality of a food source 3

4 Distance to food source Distance to food source The orientation of the straight run in the waggle dance conveys the direction of the food source, relative to the position of the sun The duration or tempo of the straight runs conveys the distance between nest and target: Dance tempo slows down with increasing distance to the food source. Quality of food source The intensity of the dance conveys the quality of the food source Learning establishes specific links between experience and behavior Innate behavior is developmentally fixed and does not vary among individuals Experience and behavior Cross-fostering studies help behavioral ecologists to identify the contribution of environment to an animal s behavior A cross-fostering study places the young from one species in the care of adults from another species Learning Learning is the modification of behavior based on specific experiences Imprinting is a behavior that includes learning and innate components and is generally irreversible It is distinguished from other learning by a sensitive period A sensitive period is a limited developmental phase that is the only time when certain behaviors can be learned 4

5 Spatial learning More complex modification of behavior based on experience with the spatial structure of the environment Types of learning Associative learning Requires an association between 2 stimuli or between a stimulus and response Behavior is conditioned through the association Two major types: Classical conditioning Operant conditioning Differ in the way associations are established Classical conditioning Pair presentation of two different stimuli causes association between the two stimuli Also called Pavlovian conditioning Operant conditioning A behavior becomes associated with its consequences Trial-and-error learning 5

6 Habituation A type of nonassociative learning An individual learns NOT to respond to a stimulus that has neither good nor bad consequences Pigeons in cities learn that people are no threat and do not flee from them Deer become increasingly tame in parks Ability to ignore signals is adaptive Cognition and problem solving Cognition is a process of knowing that may include awareness, reasoning, recollection, and judgment Problem solving is the process of devising a strategy to overcome an obstacle Social learning 6

7 Vervet monkeys give three specific alarm calls, depending on threat detected Vervet monkey alarm calls In response to the snake warning call, the troupe of vervets will all stand up on their hind legs in the open and look around on the ground In response to the leopard warning call, the members of the troupe run up to the top of the nearest tree In response to the eagle warning call, the members of the troupe run into a nearby bush Maximize benefits of nutrition versus costs of obtaining food Optimal foraging model Mating systems Male Competition for Mates In many species, mating is promiscuous, with no strong pair-bonds or lasting relationships In monogamous relationships, one male mates with one female Males and females with monogamous mating systems have similar external morphologies (a) Monogamous species (b) Polygynous species Male competition for mates is a source of intrasexual selection that can reduce variation among males Such competition may involve agonistic behavior, an often ritualized contest that determines which competitor gains access to a resource (c) Polyandrous species 7

8 Altruism Natural selection favors behavior that maximizes an individual s survival and reproduction These behaviors are often selfish On occasion, some animals behave in ways that reduce their individual fitness but increase the fitness of others This kind of behavior is called altruism, or selflessness Selfless behavior can be explained by inclusive fitness Hamilton s Rule and Kin Selection William Hamilton proposed a quantitative measure for predicting when natural selection would favor altruistic acts among related individuals Three key variables in an altruistic act Benefit to the recipient (B) Cost to the altruistic (C) Coefficient of relatedness (the fraction of genes that, on average, are shared; r) Partnerships in which mutual exchanges of altruistic acts occur because they benefit both participants Reciprocal altruism is limited to species with stable social groups where individuals meet repeatedly, and cheaters (who don t reciprocate) are punished Vampire bats Share blood Reciprocal altruism 8