Chapter 51 Behavioural Ecology

Studying behaviour Humans have probably studied animal behaviour for as long as we have lived on Earth As hunters knowledge of animal behaviour was essential to human survival

The modern scientific discipline of behavioural ecology extends observations of animal behaviour by studying how such behaviour is controlled and how it develops, evolves, and contributes to survival and reproductive success

Concept 51.1: behavioural ecologists distinguish between proximate and ultimate causes of behaviour The scientific questions that can be asked about behaviour can be divided into two classes those that focus on the immediate stimulus and mechanism for the behaviour those that explore how the behaviour contributes to survival and reproduction

What Is behaviour? Behaviour is what an animal does and how it does it includes muscular and nonmuscular activity Figure 51.2 Dorsal fin Anal fin

Learning is also considered a behavioural process

Proximate and Ultimate Questions Proximate, or “how,” questions about behaviour focus on the environmental stimuli that trigger a behaviour focus on the genetic, physiological, and anatomical mechanisms underlying a behavioural act e.g. How does day length influence breeding in birds? increased day (environmental stimuli) length triggers hormone production associated with reproduction like singing & nest building

Ultimate, or “why,” questions about behaviour address the evolutionary significance of a behaviour Why did natural selection favour this type of behaviour? Proximate & ultimate causation are linked e.g. many animals breed during spring & summer because of warmth of seasons abundant food supply may increase chances of offspring surviving

Ethology Ethology is the scientific study of animal behaviour particularly in natural environments Karl von Frisch, Konrad Lorenz, & Niko Tinbergen What are the questions that must be answered to understand any behaviour? What is the mechanistic basis of the behaviour, including chemical, anatomical, physiological mechanisms? How does development of an animal influence behaviour? What is the evolutionary history of the behaviour? How does behaviour contribute to survival & reproduction (fitness)?

Behaviours typically studied by ethologists Fixed Action Patterns A fixed action pattern (FAP) is a sequence of unlearned, innate behaviours that is unchangeable once initiated, is usually carried to completion

A FAP is triggered by an external sensory stimulus known as a sign stimulus

In male stickleback fish, the stimulus for attack behaviour is the red underside of an intruder Figure 51.3a (a) A male three-spined stickleback fish shows its red underside.

When presented with unrealistic models as long as some red is present, the attack behaviour occurs Figure 51.3b (b) The realistic model at the top, without a red underside, produces no aggressive response in a male three-spined stickleback fish. The other models, with red undersides, produce strong responses.

Proximate and ultimate causes for the FAP attack behaviour 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. Behaviour: 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 is a type of behaviour that includes both learning and innate components and is generally irreversible

An example of imprinting is young geese 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 behaviours 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

There are proximate and ultimate causes for this type of behaviour Figure 51.5 Behaviour: 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.

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

Concept 51.2: Many behaviours have a strong genetic component Biologists study the ways both genes and the environment influence the development of behavioural phenotypes nature-versus-nurture issue is not about whether genes or environment influence behaviour how are both involved? Behaviour that is developmentally fixed is called innate behaviour and is under strong genetic influence

Directed Movements Many animal movements These types of movements are under substantial genetic influence These types of movements are called directed movements

Kinesis A kinesis is a simple change in activity or turning rate in response to a stimulus

Pill 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.

Taxis A taxis is a more or less automatic, oriented movement toward or away from a stimulus

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

Migration Many features of migratory behaviour in birds have been found to be genetically programmed Figure 51.8

e.g. blackcap = warbler – range from Cape Verde Islands to N. Europe behaviour = N. Europe populations migrate at night -CVI populations do not migrate -NE pop. exhibit migratory restlessness when held in captivity experiment = cross German with CVI blackcaps result = 40% of offspring show migratory restlessness conclusion = must be under genetic control

Animal Signals and Communication In behavioural ecology a signal is a behaviour that causes a change in another animal’s behaviour Communication is the reception of and response to signals

Animals communicate using visual, auditory, chemical, tactile, and electrical signals The type of signal used to transmit information is closely related to an animal’s lifestyle and environment

Chemical Communication Many animals that communicate through odors emit chemical substances called pheromones common among mammals & insects often relate to reproductive behaviour context is important e.g. honey bee hive inside hive pheromones maintain social order outside triggers mating with queen

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 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 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

The F1 hybrid offspring sing a song in which the length of the standard repeating unit is similar to that sung by the Chrysoperla plorabunda parent, but the volley period, that is, the interval between vibration volleys, is more similar to that of the Chrysoperla johnsoni parent. RESULTS The results of this experiment indicate that the songs sung by Chrysoperla plorabunda and Chrysoperla johnsoni are under genetic control. CONCLUSION Standard repeating unit Volley period F1 hybrids, typical phenotype

Genetic Influences on Mating and Parental behaviour A variety of mammalian behaviours are under relatively strong genetic control

Research has revealed the genetic and neural basis for the mating and parental behaviour of male prairie voles arginine-vasopressin (AVP) Figure 51.11

Concept 51.3: Environment, interacting with an animal’s genetic makeup, influences the development of behaviours Research has revealed that environmental conditions modify many of the same behaviours

Dietary Influence on Mate Choice behaviour One example of environmental influence on behaviour is the role of diet in mate selection by Drosophila mojavensis

Proportion of matings by Sonoran females Laboratory experiments have demonstrated 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 Artificial Organ pipe cactus Agria cactus Culture medium With Baja males With Sonoran males (b) Proportion of matings by Sonoran females (a)

Therese Markow and Eric Toolson proposed that the physiological basis for the observed mate preferences was differences in hydrocarbons in the exoskeletons of the flies Figure 51.13

Social Environment and Aggressive behaviour Cross-fostering studies in California mice and white-footed mice have uncovered an influence of social environment on the aggressive and parental behaviours of these mice California mice – monogamous, highly aggressive, extensive parental care white-footed mice – not monogamous, little parental care

Influence of cross-fostering on male mice Table 51.1

Learning Learning is the modification of behaviour Learned behaviours based on specific experiences Learned behaviours range from very simple to very complex

Habituation Habituation is a loss of responsiveness to stimuli that convey little or no information

Spatial Learning Spatial learning is the modification of behaviour based on experience with the spatial structure of the environment

In a classic experiment, Niko Tinbergen showed how digger wasps use landmarks to find the entrances to their nests 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. No Nest After the mother visited the nest and flew away, Tinbergen moved the pinecones a few feet to one side of the nest.

Cognitive Maps A cognitive map is an internal representation of the spatial relationships between objects in an animal’s surroundings how do you distinguish between animal using landmarks & one using cognitive map? e.g. corvids – store food in caches from which bird can retrieve food later pinyon jays & Clark’s nutcrackers store nuts in as many as thousands of caches can relocate caches can also keep track of food quality

Associative Learning In associative learning animals associate one feature of their environment with another

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

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

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 cognitive ethology – examines connection between animal’s nervous system & it’s behaviour how animal’s brain represents objects in environment many animals (including insects) capable of distinguishing “same” & “different” objects

animals have substantial ability to process information problem solving behaviour highly developed in primates & dolphins, some birds especially crows, ravens, jays

Problem solving can be learned by observing the behaviour of other animals Figure 51.17

Genetic and Environmental Interaction in Learning Genetics and environment can interact to influence the learning process Some songbirds have sensitive period for developing their songs individuals reared in silence performed abnormal songs, but if recordings of proper songs were played early in life of bird, normal songs developed

Canaries exhibit open-ended learning where they add new syllables to their song as they get older