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1MO3_Chapter 51.docx

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Department
Biology
Course
BIOLOGY 1M03
Professor
Jon Stone
Semester
Winter

Description
Behaviour Key Concepts  After describing behaviour, biologists seek to explain both its proximate and ultimate causes—meaning, how it happens at the genetic and physiological levels and how it affects the individual‘s fitness.  In a single species, behaviour may range from highly stereotyped, invariable responses to highly flexible, conditional responses and from unlearned to learned responses.  The types of learning that individuals do, the way that they communicate, and the way that they orient and navigate correlate closely with their habitat and with the challenges they face in trying to survive and reproduce.  When individuals behave altruistically, they are usually helping close relatives or individuals that help them in return. Introduction  Behaviour is action—a response to a stimulus.  Behavioural biology is essentially ecological. Ecology is the study of how organisms interact with their physical and biological environments, and behavioural biology is the study of how organisms respond to particular stimuli from those environments.  Proximate (or mechanistic) causation explains how actions occur. Ultimate (or evolutionary) causation explains why actions occur.  Efforts to explain behaviour at the proximate and ultimate levels are complementary. Types of Behaviour- An Overview  Some types of behaviour are performed in nearly the same way every time. Other types of behaviour are highly flexible.  Some types of behaviour are rapidly modified by learning, others are not.  Learning is a change in behaviour that results from a specific experience in the life of an individual. Innate Behaviour  Fixed action patterns (FAPs) are highly stereotypical behaviour patterns that are usually triggered by simple stimuli called signal stimuli or releasers.  FAPs are examples of innate behaviour, behaviour that is inherited and shows little variation based on learning or the individual's condition.  Innate behaviour is commonly observed 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. Conditional Strategies and Decision Making  Although all species show some degree of innate behaviour, it is much more common for an individual's behaviour to change in response to learning and to show flexibility in response to  Changing environmental conditions.  Animals appear to take in information about their environment and make choices after weighing the costs and benefits of responding in various ways.  Costs and benefits are measured in terms of their impact on fitness—the ability to produce offspring. What Decisions Do White-Fronted Bee-Eaters Make When Foraging?  Biologists assume that animals maximize their feeding efficiency, a hypothesis called optimal foraging.  Researchers found that birds called white-fronted bee-eaters vary their foraging behaviour depending on the distance between their nesting area (colony) and their feeding territory. How Do Female Barn Swallows Choose Mates?  Although both male and female barn swallows help build the nest and feed the young, the species exhibits a significant amount of sexual dimorphism.  Female barn swallows were found to prefer long-tailed mates. Long-tailed males are more efficient in flight and more successful in finding food, and thus have higher fitness. Why Do Some Blue head Wrasses Undergo a Sex Change?  The size-advantage hypothesis states that if a group of blue head wrasse fish are living in a territory dominated by a single male, and if that male dies, then the largest female in the group should become a male.  This change is energetically costly, but the benefit is large because that female will have more offspring as male fertilizing eggs than as a female laying eggs.  In many cases, animals have alleles that make a wide range of behaviour possible; what an individual actually does is based on decisions that change, depending on conditions. o small female typically lays 10 eggs o large female typically lays 20 eggs o harem: 6 small, 2 large females = 100 eggs per year o male dies o largest female can increase reproductive output from 20 to 80 by switching to male o switch costly in time and energy terms but benefit is great Learning  Learning is particularly important in species that have large brains and a lifestyle dominated by complex social interactions.  In such species, FAPs and other types of inflexible, stereotyped behaviours are relatively rare. Instead, each individual is capable of a wide range of behaviour. Simple Types of Learning: Classical Conditioning  One type of simple learning is classical conditioning. In classical conditioning, individuals are trained by experience to give the same response to more than one stimulus—even a stimulus that has nothing to do with the normal response.  A classic example is Pavlov‘s dogs learning to associate the presence of food with a bell, and so salivating in response to hearing the bell ring. Behaviour Imprinting  Another simple type of learning takes place in newly hatched ducks and geese. Upon hatching, these ducklings and goslings adopt as their mother the first moving thing they see.  This is called imprinting. It is fast and irreversible and occurs only during a short critical or sensitive period.  Recent research has shown that the ability of humans to learn a language shares some common characteristics with imprinting. More Complex Types of Learning: Birdsong  Depending on the bird species, song-learning behaviour falls at various locations on the learning continuum.  • In certain species, such as chickens, song-learning behaviour is innate and may be highly stereotyped.  In white-crowned sparrows, singing is heavily influenced by learning, but learning is constrained to certain periods and occurs only in response to certain stimuli.  Singing in mockingbirds, parrots, and some other species is the most flexible, as these birds continue to learn new songs throughout their lives. Can Animals Think?  Several types of learning exist, and the ability to learn varies widely among species.  Cognition (thinking) is the recognition and manipulation of facts about the world, combined with the ability to form concepts and gain insights.  New Caledonian crows can make tools and solve complex problems, which suggest that they can think.  This crows-can-think hypothesis is supported by experimental evidence. What Is the Adaptive Significance of Learning?  As an ultimate cause, learning is an adaptation that helps organisms cope with challenges from their environment.  The type of learning that occurs in a given species is correlated with the type of environmental unpredictability it encounters. Sexual Activity in Anolis Lizards  Sexual activity in Anolis lizards provides an example. These lizards have a distinct breeding season.  A series of experiments showed that this is a condition-dependent behaviour controlled by hormones.  Two types of stimulation are necessary to produce the hormonal changes that lead to sexual behaviour. Females need to e
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