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Behavior Introduction. Fiddler crabs feed with the small claw and wave the large claw Why do male fiddler crabs engage in claw waving behavior? Claw waving is used to repel other males and to attract females Claw waving is a behavior. Behavior.
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Behavior Introduction • Fiddler crabs feed with the small claw and wave the large claw • Why do male fiddler crabs engage in claw waving behavior? • Claw waving is used to repel other males and to attract females • Claw waving is a behavior
Behavior • Organisms respond to changes in their environment through behavioral and physiological mechanisms • 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 • Innate behavior is developmentally fixed and does not vary among individuals • Learning is the modification of behavior based on specific experiences • Behavioral ecology is the study of the ecological and evolutionary basis for animal behavior
Examples include: • Hibernation (dormancy in response to cold) • Migration (a regular, long-distance change in location) • Estivation (dormancy in response to heat), • Taxis (innate directional movement) • Kinesis (innate non-directional movement, faster or slower depending on stimulus) • Nocturnal (night) and diurnal (day) activity • Courtship
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 • Communication occurs through various mechanisms
Animals use visual, audible, tactile, electrical and chemical signals to indicate dominance, find food, establish territory and ensure reproductive success • Examples include • Bird songs • Pack behavior in mammals • Herd, flock, and schooling behavior in animals • Colony and swarming behavior in insects • Bee dances
Figure 51.5 (b) Round dance(food near) (c) Waggle dance(food distant) A C B A B C A bee returning from the field performs a dance to communicate information about the distance and direction of a food source (a) Worker bees 30° Beehive 30° Location Location Location
In animals, internal and external signals regulate a variety of physiological responses that synchronize with environmental cycles and cues • May be daily or seasonal • Circadian rhythms - the physiological cycle of about 24 hours that is present in all eukaryotes and persists even in the absence of external cues • Sleep/awake cycles, leads to jet lag in humans • Seasonal behaviors include hibernation, estivation and migration • Reproduction is also a seasonal behavior due to the need for additional energy
Other living systems have a variety of signal behaviors or cues that produce changes in the behavior of other organisms and can result in differential reproductive success • Example: coloration and/or fragrance in flowers • Signals also regulate responses in fungi, protists and bacteria • When conditions are appropriate, reproduction will occur through fruiting body formation in fungi, slime molds and bacteria
Responding to environmental information is vital to natural selection • In phototropism in plants, changes in the light source lead to differential growth, resulting in maximum exposure of leaves to light for photosynthesis • Photoperiodism in plants results in flowering and/or preparation for winter due to changes in length of night
Timing and coordination of behavior are regulated by various mechanisms and are important in natural selection • Individuals can act on information and communicate it with others
Organisms exchange information with each other in response to internal changes and external cues, which can change behavior • Cooperative behavior within populations contributes to the survival of the populations • Examples include fight or flight response, warnings/alarms about predators, protection of the young, and avoidance responses • Also includes pack behavior in mammals; herd, flock, and schooling behavior in animals; and colony and swarming behavior in insects
Cooperative behavior between populations also contributes to the survival of the populations • Examples include mutualistic relationships such as bacteria in digestive tracts of animals, and the relationship between flowers and pollinators
Natural selection favors innate and learned behaviors that increase survival and reproductive fitness • Examples include • Parent and offspring interactions • Migration patterns • Courtship and mating behaviors • Foraging in bees and other animals • Avoidance behaviors to electric fences, poisons, or traps
Henry Beston • Henry Beston, who dedicated himself as a "writer/naturalist", is considered one of the fathers of the modern environmental movement. • He lived in a 20x16 house (below in a 1973 photo) for about two years. The house was built in June 1925 and was “claimed by the sea” in February 1978. • His book The Outermost House has been called one of the motivating factors behind the establishment of the Cape Cod National Seashore. • Author Rachel Carson said that Beston was the only author who ever influenced her writing.
Henry Beston • “We need another and a wiser and perhaps a more mystical concept of animals. In a world older and more complete than ours they move finished and complete, gifted with extensions of the senses we have lost or never attained, living by voices we shall never hear. They are not brethren, they are not underlings; they are other nations, caught with ourselves in the net of life and time, fellow prisoners of the splendor and travail of the earth.”
Behavioral Ecology • Four questions to be asked about animal behavior • 1. What stimulus elicits the behavior, and what physiological mechanisms mediate the response? • 2. How does the animal’s experience during growth and development influence the response? • 3. How does the behavior aid survival & reproduction? • 4. What is the behavior’s evolutionary history?
Fixed Action Patterns • Sequence of innate behaviors that is unchangeable • Once initiated, it is usually carried to completion • Triggered by an external cue known as a sign stimulus • Scientist observed male stickleback fish responding to a passing red truck • In male stickleback fish, the stimulus for attack behavior is the red underside of an intruder • Even shown unrealistic models, the attack behavior occurs as long as some red is present
Figure 51.2 (a) (b)
Migration • Environmental cues can be sign stimuli that trigger movement in a particular direction • Animals can orient themselves using • Position of the sun and their circadian clock • Position of the North Star • Earth’s magnetic field
Pheromones • Many animals communicate through odors or chemical substances called pheromones • A female moth can attract a male moth several kilometers distant • A honeybee queen produces a pheromone that affects the development and behavior of female workers and male drones • When a minnow or catfish is injured, an alarm substance in the fish’s skin disperses in the water, inducing a fright response among fish in the area
Figure 51.6 (a) Minnowsbefore alarm Minnowsafter alarm (b)
Learning, Experience and Behavior • What is the role of nature (genetic influences)? • What is the role of nurture (social influences)? • Cross-fostering studies help answer the question • These place the young from one species in the care of adults from another species
Studies of California mice & white-footed mice • Cross-fostered mice developed some behaviors that were consistent with their foster parents
Imprinting • Includes both learning and innate components and is generally irreversible • It is distinguished from other learning by a sensitive period • This is a limited developmental phase that is the only time when certain behaviors can be learned
An example of imprinting is young geese following their mother • Konrad Lorenz showed that when baby geese spent the first few hours of their life with him, they imprinted on him as their parent
Figure 51.7a (a) Konrad Lorenz and geese
Conservation biologists have taken advantage of imprinting in programs to save the whooping crane from extinction • Young whooping cranes can imprint on humans in “crane suits” who then lead crane migrations using ultra-light aircraft • Technique also used in “Winged Migration”
Figure 51.7b (b) Pilot and cranes
Spatial Learning & Cognitive Maps • Spatial learning is a more complex behavior based on experience with the spatial structure of the environment • Example: Bees returning to hive • A cognitive map is an internal representation of spatial relationships between objects in an animal’s surroundings • Example: Clark’s nutcrackers can find food hidden in caches located halfway between particular landmarks
Associative Learning • Animals associate one feature of their environment with another • Classical conditioning: An arbitrary stimulus is associated with a reward or punishment • A dog that repeatedly hears a bell before being fed will salivate in anticipation at the bell’s sound • Operant conditioning: An animal learns to associate one of its behaviors with a reward or punishment • It is also called trial-and-error learning • A rat that is fed after pushing a lever will learn to push the lever in order to receive food • A predator may learn to avoid a specific type of prey associated with a painful experience
Cognition & Problem Solving • Cognition may include awareness, reasoning, recollection, and judgment • Problem solving is the process of devising a strategy to overcome an obstacle • Chimpanzees can stack boxes in order to reach suspended food • Ravens obtained food suspended from a branch by a string by pulling up the string
Social Learning • Learning through the observation of others and forms the roots of culture • Young chimpanzees learn to crack palm nuts with stones by copying older chimpanzee • Vervet monkeys give and respond to distinct alarm calls for different predators
Culture is information transfer through observation or teaching that influences behavior of individuals in a population • Can alter behavior and influence the fitness of individuals
Natural Selection and Behavior • Behavior enhances survival and reproductive success in a population
Foraging Behavior • Natural selection refines behaviors that enhance the efficiency of feeding • Foraging, or food-obtaining behavior, includes recognizing, searching for, capturing, and eating food items
Evolution of Foraging Behavior • Drosophila melanogaster • Larvae in high-density populations benefit from foraging farther for food • Larvae in low-density populations benefit from short-distance foraging • Natural selection favors different alleles depending on the density of the population • Under laboratory conditions, evolutionary changes in the frequency of these two alleles were observed over several generations
Optimal Foraging Model • Shows foraging behavior as a compromise between benefits of nutrition and costs of obtaining food • Costs include energy expenditure and the risk of being eaten while foraging • Natural selection should favor behavior that minimizes costs and maximizes benefits
Optimal foraging behavior is demonstrated by the Northwestern crow • A crow will drop a whelk from a height to break its shell and feed on the soft parts • The crow faces a trade-off between the height from which it drops the whelk and the number of times it must drop the whelk • Researchers determined that the total flight height (i.e., total energy expenditure) was minimized at a drop height of 5 m • The average flight height for crows is 5.23 m
Balancing Risk and Reward • Risk of predation affects foraging behavior • Mule deer are more likely to feed in open forested areas where they are less likely to be killed by mountain lions
Mating Behavior and Mate Choice • Mating behavior includes seeking or attracting mates, choosing among potential mates, competing for mates, and caring for offspring
Mating Systems and Sexual Dimorphism • 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
In polygamous relationships, an individual of one sex mates with several individuals of the other sex • These species are usually sexually dimorphic: males and females look different • Polygamous relationships can be either polygynous or polyandrous
Polygyny: One male mates with many females • Males are usually more showy and larger than the females
Polyandry: One female mates with many males • Females are often more showy than the males
Mating Systems and Parental Care • Needs of the young are an important factor constraining evolution of mating systems • Consider bird species where chicks need a continuous supply of food • A male maximizes his reproductive success by staying with his mate and caring for his chicks (monogamy) • Consider bird species where chicks are soon able to feed and care for themselves • A male maximizes his reproductive success by seeking additional mates (polygyny)
