45.1 For any behavior, we can ask what causes it, how it develops, what adaptive function it serves, and how it evolved.
Tinbergen pointed out that questions about animal behavior can be asked at four different levels of analysis, focusing on cause, development, function, and evolution. page 982
The four questions have different answers, and all may be correct explanations of the behavior. page 982
Behavior can be innate (it is carried out in the absence of experience), or learned (it depends on experience). page 982
45.2 Animal behavior is shaped in part by genes acting through the nervous and endocrine systems.
Most behavior is produced by the interaction between genes (nature) and environment (nurture). page 983
A fixed action pattern is a stereotyped sequence of behaviors that, once initiated by a key stimulus, always goes to completion. page 983
Stimuli are recognized by feature detectors, which are specialized sensory receptors of the nervous system. page 984
Hormones can affect behavior through their wide-
The extent to which genes influence a behavior can be determined by crossing closely related species having different behaviors and analyzing the behavior of the offspring. page 986
Most behaviors are influenced by many genes, but a few are strongly influenced by a single gene. page 987
Molecular studies are providing new ways to understand the role of genes in behavior in laboratory animals. page 987
45.3 Learning is a change of behavior as a result of experience.
Non-
Habituation, a form of non-
Sensitization, another form of non-
Associative learning occurs when an animal links two separate events. page 990
Classical conditioning is a form of associative learning that occurs when two stimuli are paired and a novel association is made between a formerly neutral stimulus and a behavior. page 990
Operant conditioning is a form of associative learning that occurs when a behavior is rewarded or punished, making the behavior more likely or less likely to occur, respectively. page 990
Imitation and imprinting are forms of learning. page 990
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45.4 Orientation, navigation, and biological clocks all require information processing.
Kineses are undirected movements, whereas taxes are directed movements. page 992
Long-
Biological clocks control some physiological and behavioral aspects of animals. page 993
45.5 Communication involves an interaction between a sender and a receiver.
Communication is an interaction between two individuals, the sender and the receiver, and often involves attempts by the sender to manipulate the behavior of the receiver. page 995
Communication can evolve by the modification of noncommunicative aspects of an animal’s behavior. page 995
Bird song is a rich form of communication that is often learned during a sensitive period. Acquisition of bird song proceeds through distinct stages. page 996
The dance language of honeybees communicates information about the location and direction of a food source. page 997
45.6 Social behavior is shaped by natural selection.
One of the most perplexing behaviors from the standpoint of natural selection is altruism, in which an organism reduces its own fitness by acts that benefit others. page 997
Group selection is the idea that altruistic behaviors can evolve if they benefit the group, not the individual, but this idea is not widely accepted. page 998
Reciprocal altruism requires that individuals interact regularly and remember each other so that they can “pay back” past favors. page 999
Kin selection is the concept that altruistic behaviors can evolve if they benefit close relatives. page 999
Choose a behavior described in this chapter and ask the four kinds of question that Tinbergen might have asked about it.
Recall the example of Aquaspirillum bacteria being attracted to a magnetic pole. What causes (or what is the mechanism that drives) this movement of Aquaspirillum toward a magnetic pole (does it have to do with iron oxide within the bacteria themselves)? Has this bacterial behavior developed as a result of specific genetic or environmental factors (i.e., to what extent is this an innate or learned behavior)? Why would moving toward a magnetic pole convey greater reproductive success to a bacterium? Did this behavior of moving toward a magnetic pole evolve from random bacterial movements, or from some earlier behavioral trait?
Explain the difference between innate and learned behavior and provide an example of each.
An innate behavior is one that an organism performs instinctively. For example, when a first-
Explain, with an example, how crosses between closely related species can help us understand the genetic basis of behavior.
Sometimes there are distinct stereotyped differences in simple behavior between closely related species. By crossing the species and assessing the behavior of hybrids, we can identify the extent of the genetic control of the behavior and, with further crosses, possibly work out how many genes are involved. Consider a case of two behaviors in related species that are entirely learned from the mother: The hybrids in this case will show the behavior of the mother regardless, and we can conclude that the behavior is learned, rather than innate. Recall William Dilger’s experiment of mating two types of lovebirds with different nest-
Distinguish between associative and non-
With associative learning, an organism learns that a particular behavior will result in a specific outcome (whether positive or negative), whereas non-
Differentiate between a kinesis and a taxis.
Depending on the stimulus, organisms can undertake different types of movements. An organism can either move toward or away from a stimulus in a directed manner (remember the example of bacteria moving directly toward a magnetic pole). A taxis denotes this kind of directed movement. In contrast, stimuli can also induce undirected movements or kineses, where an organism moves toward or away from a stimulus in a random pattern (remember the example of bacteria making undirected turns to escape high-
Explain why many biologists would not consider just any transfer of information between a sender and receiver to be a form of communication.
The term “communication” suggests that two individuals are consciously exchanging information. Recall the example of a vervet monkey serving as a lookout for its family group. When a predator approaches, this lookout (the sender of information) sounds an alarm to the rest of its family (the receivers of information). This is a conscious exchange of information, where the vervet monkey wants its family members to hear the alarm and respond by taking cover or fleeing. However, many exchanges of information in biology aren’t always conscious or intentional; sometimes a sender doesn’t want to communicate a certain piece of information to a receiver, but does so inadvertently. Consider a hunter tracking a deer. The deer leaves tracks in a forest, which signals to the hunter that a deer has passed through the area. Conversely, in certain instances a deer can detect a hunter by his smell. In neither case does the deer or hunter want to provide information about their location to the other party, but they do so unintentionally. This unintentional exchange of information is why many biologists prefer not to apply the term “communication” to this type of exchange.
Describe how an altruistic behavior might evolve by kin selection.
An altruistic behavior is one of “self-