BehavioralEcology

Chapter 51:

Chapter 51 Behavioral Ecology

Behavioral Ecology:

Behavioral Ecology Ethology is the scientific study of animal behavior Studies how behavior is controlled, develops, evolves, and contributes to survival and reproductive success The scientific questions can be divided into Those that focus on the immediate stimulus and mechanism for the behavior Those that explore how the behavior contributes to survival and reproduction

What Is Behavior?:

What Is Behavior? Behavior Is what an animal does and how it does it Includes muscular and nonmuscular activity Learning is also considered a behavioral process Figure 51.2 Dorsal fin Anal fin

Proximate and Ultimate Questions:

Proximate and Ultimate Questions Proximate, or “how,” questions focus on the environmental stimuli that trigger a behavior the genetic, physiological, and anatomical mechanisms underlying a behavioral act Ultimate, or “why,” questions Address the evolutionary significance of a behavior

Fixed Action Patterns:

Fixed Action Patterns A fixed action pattern (FAP) Is a sequence of unlearned, innate behaviors that is unchangeable Once initiated, is usually carried to completion Is triggered by an external sensory stimulus Known as a sign stimulus

EXAMPLE (FAP):

EXAMPLE (FAP) In male stickleback fish, the stimulus for attack behavior is the red underside of an intruder As long as some red is present, the attack behavior occurs Figure 51.3a (a) A male three-spined stickleback fish shows its red underside. Figure 51.3b (b) The realistic model at the top produces no aggressive response, the other models, with red undersides, produce strong responses.

EXAMPLE (Causes of FAP):

EXAMPLE (Causes of FAP) Proximate and ultimate causes for the FAP attack behavior in male stickleback fish Figure 51.4 ULTIMATE CAUSE: By chasing away other male sticklebacks, a male decreases the chance that eggs laid in his nesting territory will be fertilized by another male. BEHAVIOR: A male stickleback fish attacks other male sticklebacks that invade its nesting territory. PROXIMATE CAUSE: The red belly of the intruding male acts as a sign stimulus that releases aggression in a male stickleback.

Imprinting:

Imprinting Imprinting is a type of behavior That includes both learning and innate components and is generally irreversible Imprinting is distinguished from other types of learning by a sensitive period A limited phase in an animal’s development that is the only time when certain behaviors can be learned An example of imprinting is young geese following their mother

Causes of Imprinting:

Causes of Imprinting There are proximate and ultimate causes for this type of behavior Figure 51.5 BEHAVIOR: Young geese follow and imprint on their mother. PROXIMATE CAUSE: During an early, critical developmental stage, the young geese observe their mother moving away from them and calling. ULTIMATE CAUSE: On average, geese that follow and imprint on their mother receive more care and learn necessary skills, and thus have a greater chance of surviving than those that do not follow their mother.

Imprinting:

Imprinting Conservation biologists have taken advantage of imprinting In programs to save the whooping crane from extinction Figure 51.6

Behavior and Genetics:

Behavior and Genetics Many behaviors have a strong genetic component Behavior that is developmentally fixed Is called innate behavior and is under strong genetic influence

Directed Movements:

Directed Movements Many animal movements are under substantial genetic influence These types of movements are called directed movements A kinesis is a simple change in activity or turning rate in response to a stimulus A taxis is a more or less automatic, oriented movement toward or away from a stimulus

EXAMPLE (Kinesis):

EXAMPLE (Kinesis) Sow bugs Become more active in dry areas and less active in humid areas Figure 51.7a Dry open area Moist site under leaf (a) Kinesis increases the chance that a sow bug will encounter and stay in a moist environment.

EXAMPLE (Taxis):

EXAMPLE (Taxis) Many stream fish exhibit positive rheotaxis Where they automatically swim in an upstream direction Figure 51.7b Direction of river current (b) Positive rheotaxis keeps trout facing into the current, the direction from which most food comes.

Migration:

Migration Many features of migratory behavior in birds Have been found to be genetically programmed Figure 51.8

Animal Signals and Communication:

Animal Signals and Communication In behavioral ecology a signal is a behavior that causes a change in another animal’s behavior Organisms communicate using Visual Auditory Chemical Tactile Electrical signals

Chemical Communication:

Chemical Communication Many animals that communicate through odors 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 51.9a, b (a) Minnows are widely dispersed in an aquarium before an alarm substance is introduced. (b) Within seconds of the alarm substance being introduced, minnows aggregate near the bottom of the aquarium and reduce their movement.

Auditory Communication:

Auditory Communication Experiments with various insects have shown that courtship songs are under genetic control Charles Henry, Lucía Martínez, and ent Holsinger crossed males and females of Chrysoperla plorabunda and Chrysoperla johnsoni, two morphologically identical species of lacewings that sing different courtship songs. EXPERIMENT SONOGRAMS Chrysoperla plorabunda parent Vibration volleys Standard repeating unit Chrysoperla johnsoni parent Volley period crossed with Standard repeating unit The researchers recorded and compared the songs of the male and female parents with those of the hybrid offspring that had been raised in isolation from other lacewings. Volley period

Environment influences behaviors:

Environment influences behaviors Research has revealed that environmental conditions modify many of the same behaviors One example is the role of diet in mate selection by Drosophila mojavensis That the type of food eaten during larval development influences later mate choice in females Figure 51.12 William Etges raised a D. mojavensis population from Baja California and a D. mojavensis population from Sonora on three different culture media: artificial medium, agria cactus (the Baja host plant), and organ pipe cactus (the Sonoran host plant). From each culture medium, Etges collected 15 male and female Baja D. mojavensis pairs and 15 Sonoran pairs and observed the numbers of matings between males and females from the two populations. EXPERIMENT When D. mojavensis had been raised on artificial medium, females from the Sonoran population showed a strong preference for Sonoran males (a). When D. mojavensis had been raised on cactus medium, the Sonoran females mated with Baja and Sonoran males in approximately equal frequency (b). RESULTS The difference in mate selection shown by females that developed on different diets indicates that mate choice by females of Sonoran populations of D. mojavensis is strongly influenced by the dietary environment in which larvae develop. CONCLUSION 100 75 50 25 0 Artificial Organ pipe cactus Agria cactus Culture medium With Baja males With Sonoran males (b) Proportion of matings by Sonoran females (a)

Social Environment and Aggressive Behavior:

Social Environment and Aggressive Behavior Cross-fostering studies in California mice and white-footed mice have uncovered an influence of social environment on the aggressive and parental behaviors of these mice Table 51.1

Learning:

Learning Learning is the modification of behavior based on specific experiences Habituation is a loss of responsiveness to stimuli that convey little or no information Spatial learning is the modification of behavior based on experience with the structure of the environment Associative learning is when animals associate one feature of their environment with another

EXAMPLE (Associative Learning):

EXAMPLE (Associative Learning) In a classic experiment, Niko Tinbergen Showed how digger wasps use landmarks to find the entrances to their nests A cognitive map is an internal representation of the spatial relationships between objects in an animal’s surroundings After the mother visited the nest and flew away, Tinbergen moved the pinecones a few feet to one side of the nest. Figure 51.14 CONCLUSION A female digger wasp excavates and cares for four or five separate underground nests, flying to each nest daily with food for the single larva in the nest. To test his hypothesis that the wasp uses visual landmarks to locate the nests, Niko Tinbergen marked one nest with a ring of pinecones. EXPERIMENT Nest When the wasp returned, she flew to the center of the pinecone circle instead of to the nearby nest. Repeating the experiment with many wasps, Tinbergen obtained the same results. RESULTS The experiment supported the hypothesis that digger wasps use landmarks to keep track of their nests. Nest No Nest

Classical Conditioning:

Classical Conditioning Classical conditioning is a type of associative learning In which an arbitrary stimulus is associated with a reward or punishment Figure 51.15 Before stimulus Influx of water alone Influx of alarm substances Influx of pike odor Day 1 Day 3 Control group Control group Experimental group Experimental group Relative activity level

Operant Conditioning:

Operant Conditioning Operant conditioning is another type of associative learning In which an animal learns to associate one of its behaviors with a reward or punishment Figure 51.16

Cognition and Problem Solving:

Cognition and Problem Solving Cognition is the ability of an animal’s nervous system to perceive, store, process, and use information gathered by sensory receptors Problem solving can be learned by observing the behavior of other animals Figure 51.17

Evolution of Behavioral Traits:

Evolution of Behavioral Traits Behavioral traits can evolve by natural selection Because of the influence of genes on behavior natural selection can result in the evolution of behavioral traits in populations

Variation in Aggressive Behavior:

Variation in Aggressive Behavior Funnel spiders living in different habitats Exhibit differing degrees of aggressiveness in defense and foraging behavior Figure 51.19 50 40 30 20 10 0 Time to attack (seconds) Field Lab-raised generation 1 Lab-raised generation 2 Desert grassland population Riparian population 60 Population

Laboratory Studies of Drosophila Foraging Behavior:

Laboratory Studies of Drosophila Foraging Behavior Studies of Drosophila populations raised in high- and low-density conditions Show a clear divergence in behavior linked to specific genes Figure 51.20 14 12 10 8 6 2 0 Average path length (cm) 4 L1 L2 L3 H1 H2 H3 H4 H5 D. Melanogaster lineages Low population density High population density

Migratory Behaviors:

Migratory Behaviors Migratory orientation of wintering adult birds captured in Britain Was very similar to that of laboratory-raised birds Figure 51.21b (b) Wintering blackcaps captured in Britain and their laboratory-raised offspring had a migratory orientation toward the west, while young birds from Germany were oriented toward the southwest. N E S W Adults from Britain and F 1 offspring of British adults N E S W Young from SW Germany Mediterranean Sea BRITAIN GERMANY

Natural Selection and Behaviors:

Natural Selection and Behaviors Natural selection favors behaviors that increase survival and reproductive success The genetic components of behavior Evolve through natural selection Behavior can affect fitness Through its influence on foraging and mate choice

Foraging Behavior:

Foraging Behavior Optimal foraging theory Views foraging behavior as a compromise between the benefits of nutrition and the costs of obtaining food Reto Zach Conducted a cost-benefit analysis of feeding behavior in crows The crows eat molluscs called whelks but must drop them from the air to crack the shells

Cost-Benefit Analysis:

Cost-Benefit Analysis Zach determined that the optimal flight height in foraging behavior Correlated with a fewer number of drops, indicating a trade-off between energy gained (food) and energy expended Figure 51.22 60 50 40 30 20 10 0 Average number of drops 2 3 5 7 15 Average number of drops Drop height preferred by crows 125 100 25 75 50 Total flight height Total flight height (number of drops  drop height) Height of drop (m)

Risk of Predation:

Risk of Predation Research on mule deer populations Has shown that predation risk affects where the deer choose to feed Figure 51.24 70 60 40 30 20 10 0 Predation occurrence (%) 50 Relative deer use Relative deer use Predation risk Open Forest edge Habitat Forest interior 0 5 10 15 20

Mating Behavior and Mate Choice:

Mating Behavior and Mate Choice The mating relationship between males and females varies a greatly from species to species Promiscuous- no lasting relationships Monogomous – one male & one female birds Polygyny – one male and many females Deer, wild horses, lions Polyandry – one female mates with many males

Sexual Selection and Mate Choice:

Sexual Selection and Mate Choice In intersexual selection Members of one sex choose mates on the basis of particular characteristics Intrasexual selection Involves competition among members of one sex for mates

EXAMPLE (Intersexual selection):

EXAMPLE (Intersexual selection) Imprinting of female chicks on males with more ornamentation Affects mate selection as adults Figure 51.28 Experimental Groups Control Group Parents not ornamented Both parents ornamented Males ornamented Females ornamented Results Females reared by ornamented parents or ornamented fathers preferred ornamented males as mates. Females reared by ornamented mothers or nonornamented parents showed no preference for either ornamented or nonornamented males. Males reared by all experimental groups showed no preference for either ornamented or nonornamented female mates.

EXAMPLE (Intrasexual selection):

EXAMPLE (Intrasexual selection) Such competition may involve antagonistic behavior An often ritualized contest that determines which competitor gains access to a resource Figure 51.30

Going Against Natural Selection:

Going Against Natural Selection The concept of inclusive fitness can account for most altruistic social behavior Many social behaviors are selfish Natural selection favors behavior That maximizes an individual’s survival and reproduction

Altruism:

Altruism 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 In naked mole rat populations nonreproductive individuals may sacrifice their lives protecting the reproductive individuals from predators Figure 51.33

Inclusive Fitness:

Inclusive Fitness Altruistic behavior can be explained by inclusive fitness The total effect an individual has on proliferating its genes by producing its own offspring and by providing aid that enables close relatives to produce offspring

Hamilton’s Rule and Kin Selection:

Hamilton’s Rule and Kin Selection Hamilton proposed a measure for predicting when natural selection would favor altruistic acts among related individuals The three key variables in an altruistic act are The benefit to the recipient The cost to the altruist The coefficient of relatedness Kin selection favors altruistic behavior by enhancing reproductive success of relatives

Coefficient of Relatedness:

Coefficient of Relatedness The coefficient of relatedness Is the probability that two relatives may share the same genes Figure 51.34 Parent A Parent B  OR Sibling 1 Sibling 2 1 / 2 (0.5) probability 1 / 2 (0.5) probability

Hamilton’s rule:

Hamilton’s rule Natural selection favors altruism when the benefit multiplied by the coefficient of relatedness exceeds the cost to the altruist An example of kin selection and altruism is the warning behavior observed in Belding’s ground squirrels Male Female Age (months) Mean distance moved from natal burrow (m) 300 200 100 0 0 2 3 4 12 13 14 15 25 26 Figure 51.35

Reciprocal Altruism:

Reciprocal Altruism Altruistic behavior toward unrelated individuals Can be adaptive if the aided individual returns the favor in the future This type of altruism Is called reciprocal altruism

Social Learning:

Social Learning Social learning Forms the roots of culture Culture can be defined as a system of information transfer through observation or teaching That influences the behavior of individuals in a population

Mate Choice Copying:

Mate Choice Copying Mate choice copying is a behavior in which individuals in a population copy the mate choice of others Has been extensively studied in the guppy Poecilia reticulata Figure 51.36 Male guppies with varying degrees of coloration Control Sample Female guppies prefer males with more orange coloration. Experimental Sample Female model engaged in courtship with less orange male Female guppies prefer less orange males that are associated with another female.

Social Learning of Alarm Calls:

Social Learning of Alarm Calls Vervet monkeys produce a complex set of alarm calls Infant monkeys give undiscriminating alarm calls at first but learn to fine-tune them by the time they are adults Figure 51.37

Slide 48:

No other species Comes close to matching the social learning and cultural transmission that occurs among humans Figure 51.38