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Chapter 51

Unit 9 - Chapter 51 Bio 1M03 .docx

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James S Quinn

Bio 1M03 Unit Nine: Ecology Chapter 51: Behaviour  Behaviour – an action; the response to a stimulus  Ecology – the study of how organisms interact with their physical and biological environments  Behavioural Biology – the study of how organisms respond to particular stimuli from their physical and biological environments  Proximate (mechanical) Causation – explains how actions occur in terms of the neurological, hormonal and skeletal-muscular mechanisms involved  Ultimate (evolutionary) Causation – explains why actions occur, based on their evolutionary consequences and history  Efforts to explain behaviour at the proximate and ultimate levels are complementary – to understand what an organism is doing, biologists want to know how the behaviour happens and why 51.1 Types of Behaviour: An Overview  Learning – change in behaviour that results from a specific experience in the life of an individual  Behaviours can be o Highly Stereotyped, Fixed with little variation –or—Highly flexible, Condition dependent o Innate, no modification through learning –or—Originated and is modified through learning o Eg/ Language Acquisition – Flexible and modified through learning o Eg/ Yawning – Fixed and Innate o Eg/ Smiling – Innate, between fixed and flexible Innate Behaviour  Innate Behaviour – behaviour that is inherited and shows little variation based on learning or the individuals condition  Fixed Action Patterns (FAPs) – highly inflexible behaviour patterns o Stereotyped – performed in the same way every time o Usually triggered by releasers or sign stimuli (simple stimuli)  Common to observe innate behaviour in response to o Situations that have a high impact on fitness and demand a reflex-like, unlearned response o Situations where learning is not possible  Eg/ Web-weaving in spiders, nest building in birds – largely innate, offspring have little or no opportunity to learn behaviours; quality of web or nest has a high impact n fitness Conditional Strategies and Decision Making  It is more common for an individuals behaviour to change in response to learning and to show flexibility in response to changing environmental stimulus than to have innate behaviour  Assumed that animals do not make conscious decisions  Biologists know little about proximate mechanisms involved in flexible responses and decision making – but well understood at an ultimate level  Cost-Benefit Analysis o Animals appear to take in information about their environment and weigh the costs and benefits of responding in various ways o Cost and benefit are measured in terms of their impact on fitness – the ability to produce offspring  White-Fronted Bee-Eaters Decisions While Foraging o Optimal Foraging – individuals should forage in a way that maximized the amount of usable energy they take in, given the costs of finding and ingesting their food and the risk of being eaten while they’re at it o Test – whether optimal foraging actually occurs  White-fronted bee-eater bird – study feeding behaviour  Mated pairs dig tunnels in riverbanks and raise their young inside Bio 1M03  Many pairs build tunnels in the same location, forming colonies, because optimal locations are rare  Pairs have to fly away from the colony, capture insects, and bring the prey back to the nest  Each pair defend a specific area where only they find food  Some individuals forage a few meters from the colony – only takes a few seconds to make a round trip  Some individuals look for food hundred of meters away – several minutes for round trip  Optimal Foraging  Individuals with a large cost (longer time away) – bring back a larger mass of insects on each trip (benefit)  How Female Barn Swallows Choose Mates o Females choose males that contribute good alleles and/or resources to their offspring o Sexual dimorphism in barn swallows; males are slightly larger, more brightly colored and the outer tail feathers are about 15% longer  These traits show that the males are healthy and well fed  Long tails are more efficient in flight; more successful in finding food o Experiment  Hypothesis: Females prefer to mate with the longest-tailed mate  Experimental Setup:  Short Tail – outermost tail feathers cut  Control 1 – outermost tail feathers cut and glued back into place  Control 2 – males caught and handled, but no change in tail feathers  Elongated Tail – outermost feathers cut and elongated with feathers from other males, glued in place  Results  On average, males with longer tales mete sooner than males with shorter tails  Males with longer tails have second clutches more frequently – raise more offspring  Conclusion: Females prefer males with longer tails  Bluehead Wrasses Undergo a Sex Change o Territories that contain nesting sites and feeding areas  A group of females live inside this territory and lay eggs  A single male defends this territory and fertilizes the egg  Male is the largest individual in the group – must be large to win fights and guard the territory  When male dies – largest female changes sex and becomes male; reproductive organs begin producing sperm instead of eggs o Size Advantage Hypothesis – if a group of fish is living in a territory dominated by a single male, and if that male dies, then the largest female should switch from male to female  Suppose a small fish can lay 10 eggs a year, and a large female can lay 20 eggs  If there are 6 small and 2 large females  100 eggs  male fertilizes 100 eggs  When the male dies, the largest female can increase the number of offspring she produces from 20 to 80 by changing sex  If small fish changed sex – it would be defeated in fights; go from 10 offspring to 0 o Sex change is timely and costly – but the benefit is large 51.2 Learning  Learning occurs when behaviour changes in response to specific life experiences o Particularly important to species with large brains and a lifestyle dominated by complex social interactions Simple Types of Learning: Classical Conditioning and Imprinting  Classical Conditioning – individuals are trained by experience to give the same response to more than one stimulus – even a stimulus that is unrelated to the normal response o Eg/ Pavlov’s dogs – rang a bell each time food was presented to a dog, dog learned to associate the sound of a bell with food  in the absence of food, dogs would salivate at the sound of a bell Bio 1M03  Imprinting – upon hatching, ducklings and goslings adopt the first thing they see moving as their mother o Offspring must quickly learn to recognize and respond to their mother in order to survive o Most relevant to species that nest on the ground (eg/ ducks, geese etc.) because by following the first thing they see move, they will avoid predators and increase their fitness o Critical/Sensitive Period – short interval early in life, in which imprinting occurs o Imprinting lasts for life; offspring established identity of mother and species identity o Fast and irreversible and occurs during critical period – not typical of most types of learning  Language Acquisition in human infants – similar to that of imprinting o Critical period More Complex Types of Learning: Birdsong  Birds sing to attract males and to mark territories where they find food and raise offspring  Bird songs are (usually) unique to each species  Depending on the species, song-learning behaviour falls at various locations on the learning continuum  Experiment – taking eggs from nest, hatching them and rearing individuals in the lab in a controlled auditory environment o Young chickens and phoebes – have simple vocalization  song-learning behaviour is innate, may be highly stereotyped  Raised in isolation from other members of their species and never heard their species-specific calls – able to produce correct vocalizations as adults o White-crowned sparrows – sings complex song  singing is learning during critical period; restricted to own species song  Raised in isolation – do not sing a normal song unless they hear a tape recording of their species-specific song during the early months of life  If song of a closely related species is played during critical period – do not learn other species song; learn an abnormal song different from their own and the other species  Critical period for song learning is augmented by practice that occurs when the individual is older  Don’t begin to sing until 1 year old  Sub song o Beginning singers produce a disorganized warbling  Crystalized o Sub song becomes more and more organized and progressively closer to adult song o Adult song that remains unchanged for the rest of the individuals life  Individual must hear itself sing  Individuals who are prevented from hearing own practice never sing a normal song  Individuals deafened after adult song developed – sings normal song  Suggests two critical periods  One as a nestling – must hear song of own species  One as a one-year old – must hear themselves practice  Heavily influenced by learning – learning is constrained to certain periods of life; occurs only in response to certain types of stimuli  (Innate) Chickens --- White-Crowned Sparrows --- Mynahs, mockingbirds, lyrebirds, parrots (learn new songs) Can Animals Think?  Cognition – recognition and manipulation of facts about the world, combined with the ability to form concepts and gain insights o Cannot be observed directly  To infer that animals are thinking, researchers must design experimental; situations that require animals to manipulate facts or information and demonstrate an ability to form novel associations or insights  Eg/ New Caledonian Crows – routinely make tools to find food in the wild; tools held in beak and used to remove insect larvae (grubs) or other types of food from plant stems or crevices Bio 1M03 o Straight or curved sticks are broken off and cleaned before use  Select sticks whose width or length is appropriate for the tubes width and the foods distance from the end of the tube - insert stick into tube to fish out food o Hooks are made by breaking complex leaves into pieces o Spearing tools are constructed from a complex series of cuts and rips, made with the beak, along the edge of leaves from pandanus plants  Crows can think  Crows understand facts about the size and shape or raw material and the location of food  Crows recognize that if they choose or manipulate materials in a certain way, they can use the resulting structure as a tool to acquire food  Natural selection has favored the evolution of cognition in this species; crows with the ability to manufacture and manipulate tools have higher fitness  Eg/ Caledonian crow; small bucket with food at the bottom, handle pointing up – in the bottom of a tube to long for the beak to reach o Given a piece of wire, the crow bends the wire and uses it to pull the bucket up o Female crow can use tools to solve problems and can make tools from unfamiliar materials to solve problems What is the Adaptive Significance of Learning?  Learning is viewed as an adaptation that allows individuals to change their behaviour in response to a changing and unpredictable environment o The ability to learn varies among species – some species live in environments that are more unpredictable than others o The type of learning that occurs in a given species is correlated with the type of environmental unpredictability it encounters  Eg/ Norway rats o Adept to learning to navigate mazes  Live in sewers, walls of homes or locations where the ability to learn travel routes is essential for survival o Good at learning to avoid foods that contain poisons  In nature; feed on wide variety of fruits, seeds and insects – availability of food changes with the season; many potential food items are toxic  Eg/ Scrub Jays o Not adept at navigating mazes or learning to avoid foods o Proficient at remembering where they have cached (stored) seeds  Spatial learning and a good memory are essential for survival o Learn how to prevent theft  Live in social groups; not unusual for some members of the group to steal food that was cached by other jays in their group  Experiment – If an individual has stolen food in the past caches food while being watched; the individual will come back by itself and remove stored food to a new location 51.3 How Animals Act: Hormonal and Neural Control Sexual Activity in Anolis Lizards  Sex hormones – causes dramatic seasonal changes in behaviour; induce sexual behavior o Testosterone in males  Produced in the testes o Estradiol in females  Produced in the ovaries  Anolis Carolinensis o Live in the woodlands of the southern US o Spend winter under a log or rock o January – males emerge and establish breeding territory  Females become active a month later Bio 1M03 o April – breeding season begins o May – females are laying eggs every 10-14 days o 3 months later – breeding season ends, eggs produced by females totals twice her body mass  Anolis Lizards are most successful if they reproduce early in the spring o Food supplies are increasing o Snakes and other predators are not yet hunting lizards to feed their own young  Timing of induced sexual behaviour by sex hormones is crucial o If at any other time of the year – may be killed due to predation or not have enough food o If unsynchronized – females and males wouldn’t be able to breed with each other  Experiment o Sexually inactive adult lizards – 5 groups  Single isolated females  Groups of females  Pairs of lizards – single females with single males  Single females, each with a group of castrated males  Single females with a group of un-castrated males o Physical environment was the same – identical food, high daytime temperatures were followed by lower nighttime settings o Exposed the five groups to artificial lighting that simulated the long d
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