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University of Toronto Scarborough
Biological Sciences
Kamini Persaud

CHAPTER 53: BEHAVIOUR AND BEHAVIOURAL ECOLOGY 53.1 What Questions Do Biologists Ask About Behaviour? Ethology the study of animal behaviour from an evolutionary perspective. Proximate mechanisms that underlie behaviour are the neuronal, hormonal, and anatomical mechanisms. Most behaviours result from complex interactions between inherited anatomical and physiological mechanisms and the ability to modify behaviour as a result of experience. The ultimate causes of behaviour are the selection pressures that shaped it evolution. For many animals, much of their behaviour is unlearned and highly stereotypic (always exactly the same). Stereotypic behaviour is often species-specific in that most individuals of a given species perform the behaviour in the same way. 53.2 How Do Genes and Environment Interact to Shape Behaviour? Genes do not encode behaviours. Rather, gene products such as enzymes can affect behaviour by setting in motion a series of gene-environment interaction that underlie the development of proximate mechanisms that enable individuals to make certain behavioural responses. Experiments can distinguish between genetic and environmental influences on behaviour: 2 experimental approaches that are useful to biologist in evaluating how genes and experience interact to shape behaviours: 1. In a deprivation experiment, investigators rear a young animal so that it is deprived of all experience relevant to the behaviour under study. If it still exhibits the behaviour, may assume that the behaviour can develop without opportunities to learn it. 2. In genetic experiments, investigators alter the genomes of organisms by interbreeding closely related species, by comparing individuals that differ in only 1 or a few genes or by knocking out or inserting specific genes to determine how these manipulations affect their behaviour. Deprivation experiments: E.g. tree squirrel. Experiment showed that hereditary underlies the food-storing behaviours of the tree squirrel species, but the behaviour was expressed only when the environment provided conditions that stimulated the behaviour (the presence of a nut). Selective Breeding: Is a means of genetic manipulation that has been in use since plants and animals were 1 domesticated. It has been used extensively to select for both anatomical traits and behaviour. Interbreeding: E.g. interbreeding of duck species by Konrad Lorenz. When Lorenz crossbred duck species the hybrid offspring expressed some elements of each parents courtship display, but in new combination. He also observed that the hybrids sometimes exhibited display elements that were not in the repertoire of either parent species, but were characteristic of other species. His hybridization studies clearly demonstrated that the stereotypic motor patterns f the courtship displays are inherited. The observation that females are not interested in males performing hybrid displays is evidence that sexual selection has shaped these genetically determined behaviours. Gene knockout experiments: E.g. experiments with house mice. Female mice in which the fos gene is active gather their pups together, keep them warm and
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