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Chapter 30: Animal behaviour Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and Saint Slides prepared by Karen Burke da Silva, Flinders University 30-1 Ethology • Ethology is the study of animal behaviour • It documents behaviour and examines the causes and outcomes of observed behaviour • Studies investigate – – – – causation development adaptive value evolutionary history Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and Saint Slides prepared by Karen Burke da Silva, Flinders University 30-2 Genetics and the evolution of behaviour • Because behaviour is part of an animal’s phenotype, it is subject to natural selection and sexual selection • Selection acts where there is variation in behaviour between individuals in a population • Animal behaviour is often a balance between several alternative behaviours – hide from predators and starve; or – forage and run the risk of being eaten? Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and Saint Slides prepared by Karen Burke da Silva, Flinders University 30-3 Fig. 30.1: Bowerbirds Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and Saint Slides prepared by Karen Burke da Silva, Flinders University 30-4 Genetic markers • Behaviour has a genetic basis – mutations in genes may alter behaviour • Studies of fruit flies (Drosophila melanogaster) have identified some behaviours under genetic control – duration of copulation is affected by mutations in muscles and sensory receptors Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and Saint Slides prepared by Karen Burke da Silva, Flinders University 30-5 Selection experiments • Artificial selection is used to develop preferred traits in domesticated animals and plants – coat pattern in cats, grain yield in wheat • It can also be used to select behaviours in animals – behaviour of courting male Gryllus crickets varies—some sing, others are silent – selective breeding from singing males increases frequency of singing in subsequent generations – singing has a genetic basis Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and Saint Slides prepared by Karen Burke da Silva, Flinders University 30-6 Populations with genetic differences • Populations may exhibit differences in behaviour • Garter snakes (Thamnophis elegans) in southwestern United States live in coastal and inland regions – coastal snakes are terrestrial slug-feeders – inland snakes are aquatic frog-feeders • Feeding experiments demonstrated that food preference is inherited – preference results from selection for local conditions Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and Saint Slides prepared by Karen Burke da Silva, Flinders University 30-7 Learning and the development of behaviour • Learning is a long-term or permanent change in behaviour due to experience • Maturational effects (change in behaviour during development) are not the result of experience so they cannot be classified as learning • Imprinting is both a learned behaviour and a maturational effect – goslings and other chicks will follow the first moving object they see – imprinting occurs only within a restricted sensitive period Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and Saint Slides prepared by Karen Burke da Silva, Flinders University 30-8 Fig. 30.2: Imprinting Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and Saint Slides prepared by Karen Burke da Silva, Flinders University 30-9 Learning and the development of behaviour (cont.) • Galah (Cacatua roseicapilla) chicks raised by pink cockatoos (C. leadbeateri) show learned behaviour – Fostered galah chicks give typical galah alarm and begging calls (inherited behaviour) – But they give pink cockatoo contact calls (learned behaviour) Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and Saint Slides prepared by Karen Burke da Silva, Flinders University 30-10 Learning and the development of behaviour (cont.) • Learning can be associative or non-associative • Associative – learning in response to a stimulus – trial-and-error • Non-associative – learning without a stimulus Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and Saint Slides prepared by Karen Burke da Silva, Flinders University 30-11 Evolutionary basis of behaviour • Methods for examining the evolutionary basis of behaviour • Intraspecific comparisons – comparing behaviour of individuals within a species • Manipulative experiments – focused experimental studies of selected behaviour • Interspecific comparisons – comparing behaviour of individuals in different species Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and Saint Slides prepared by Karen Burke da Silva, Flinders University 30-12 Question 1: Which of the following is not required for a behaviour to evolve? a) The behaviour varies amongst individuals b) Some component of the behaviour is genetically inherited c) In every individual the behaviour is determined solely by its genes d) An individual’s genotype influences its phenotype e) An individual’s reproductive success depends in part on how the behaviour is performed Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and Saint Slides prepared by Karen Burke da Silva, Flinders University 30-13 Obtaining food • Animals exhibit a range of diets – have a wide variety of strategies to obtain food – predators may actively forage for prey or sit and wait (ambush it) • Foraging is not random – individuals make decisions that represent the best balance between cost (energy expended in foraging) and benefit (energy gained from food) Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and Saint Slides prepared by Karen Burke da Silva, Flinders University 30-14 Fig 30.5: Examples of the ways animals obtain food Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and Saint Slides prepared by Karen Burke da Silva, Flinders University 30-15 Foraging theory • Foraging theory evaluates costs and benefits and predicts the decision under different conditions • Other factors may influence the calculation of cost and benefit – risk of predation – intraspecific competition – interspecific competition Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and Saint Slides prepared by Karen Burke da Silva, Flinders University 30-16 Avoiding being eaten • Defence mechanisms minimise the risk of predation – fast-moving animals may outrun predators – animals may produce noxious chemicals to deter predators – camouflaged animals may be overlooked by predators – animals may mimic unrelated species Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and Saint Slides prepared by Karen Burke da Silva, Flinders University 30-17 Mimicry • Animals may mimic other organisms by visual, chemical, behavioural or acoustic resemblance • Prey animals use defensive mimicry to decrease the chance of predation – harmless species resemble unpalatable or dangerous species to avoid being eaten by predators • Predators use aggressive mimicry to increase the chance of catching prey – example: bolas spiders (Dichrostichus) produce a substance that resembles the mate-attracting pheromones of moths Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and Saint Slides prepared by Karen Burke da Silva, Flinders University 30-18 Fig. 30.6: Juvenile long-horn grasshoppers Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and Saint Slides prepared by Karen Burke da Silva, Flinders University 30-19 Living in groups • Living in groups reduces the chance of predation – probability of any individual being caught decreases as the size of the group increases – probability changes with location within the group as those on the edge have a greater chance of being eaten than those in the centre – flocking behaviour may produce a confusion effect and distract predators from singling out individuals – groups of animals may harass (mob) predators and drive them off – groups can detect predators with greater success than a single animal can Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and Saint Slides prepared by Karen Burke da Silva, Flinders University 30-20 Competition and territorial behaviour • When resources are limited, individuals may compete for them • Establishing a territory excludes competitors from resources in that area – territory-holders benefit by having exclusive access to the resources – but they pay a cost in defending the territory • Individuals, pairs or groups may hold territories Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and Saint Slides prepared by Karen Burke da Silva, Flinders University 30-21 Animal contests • Competition for resources frequently involves contests (direct conflicts) between individuals – as both individuals in a contest may suffer injuries in a physical confrontation, contests are usually settled before injury occurs – winners benefit by gaining access to the resource but pay a cost in energy expended (or injury) • Outcome of contests depends on – ability of contestants – value of resource to each contestant – which contestant owns resource Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and Saint Slides prepared by Karen Burke da Silva, Flinders University 30-22 Fig. 30.11: Contest between male red kangaroos Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and Saint Slides prepared by Karen Burke da Silva, Flinders University 30-23 Finding a mate • Animals use many methods for locating a mate • Chemical signals – female moths release pheromones to attract males, which may detect the signal from a distance of several kilometres • Auditory signals – male frogs call to attract females • Visual signals – male fireflies produce flashes of light to attract females Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and Saint Slides prepared by Karen Burke da Silva, Flinders University 30-24 Courtship • After locating each other, potential mates display courtship behaviour • Courtship behaviour – confirms that the potential mates belong to the same species – confirms that the individuals are ready to mate – may provide some indication of the fitness of the signalling mate Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and Saint Slides prepared by Karen Burke da Silva, Flinders University 30-25 Sexual selection • Elaborate displays and ornaments used in courtship are the product of sexual selection – sexual selection acts on the characteristics that influence a male’s chance of fertilising a female’s eggs • Male–male competition – intrasexual selection in which males compete with each other for females • Female choice – intersexual selection in which females choose their mates Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and Saint Slides prepared by Karen Burke da Silva, Flinders University 30-26 Fig. B30.3a: Peacock Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and Saint Slides prepared by Karen Burke da Silva, Flinders University 30-27 Courtship (cont.) • Gift-giving occurs among some species – male lygaeid bugs provide the female with a nuptial gift containing nutrients that increase the size or number of her eggs • Courtship behaviour reduces the likelihood of sexual cannibalism – eating the male may provide nutrients for egg-production Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and Saint Slides prepared by Karen Burke da Silva, Flinders University 30-28 Fig. 30.14: Lygaeid bug Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and Saint Slides prepared by Karen Burke da Silva, Flinders University 30-29 Sperm competition • If a female mates with more than one male, there may be competition between sperm to fertilise her eggs • Males reduce the risk of sperm competition by – guarding a female to prevent other males mating with her – producing chemicals in ejaculates that make females unreceptive after mating – sealing the female genitalia after mating – dislodging sperm from previous matings Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and Saint Slides prepared by Karen Burke da Silva, Flinders University 30-30 Parental care • In those species that provide parental care, one or both parents may be involved in taking care of the offspring • As with many behaviours, the amount of care depends on the balance between – benefit of increased survival rate of young – cost of lost opportunities for mating • Difference in behaviour – females commonly invest greater effort in rearing offspring than males – males may spend time seeking extra-pair copulations Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and Saint Slides prepared by Karen Burke da Silva, Flinders University 30-31 Mating systems • An individual may mate with one or more partners during a mating season • Mating systems are divided into four categories – monogamy one male mates with one female – polygyny one male mates with several females – polyandry one female mates with several males – promiscuity males and females mate with several partners Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and Saint Slides prepared by Karen Burke da Silva, Flinders University 30-32 Social organisation and co-operative behaviour • Permanent groups exhibit social behaviour – individuals in a group cooperate to find food defend the group rear young • Many groups have complex social structures depending on the interests and needs of the individuals • Conflict is avoided in some groups by establishing dominance hierarchies – pecking orders Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and Saint Slides prepared by Karen Burke da Silva, Flinders University 30-33 Fig. 30.20: Castes of the myrmicine ant Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and Saint Slides prepared by Karen Burke da Silva, Flinders University 30-34 Cooperative breeding • Cooperative breeders share the task of rearing young between members of a group • Depending on the species, family members and/or unrelated helpers assist parents to raise offspring Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and Saint Slides prepared by Karen Burke da Silva, Flinders University 30-35 Insect societies • Hymenopteran insects (bees, ants, wasps) and termites form complex eusocial societies • Eusocial societies are characterised by – overlapping generations – reproductive division of labour • Colonies are composed of – reproductive queen – sterile female workers in one or more specialised castes – reproductive males Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and Saint Slides prepared by Karen Burke da Silva, Flinders University 30-36 Insect societies (cont.) • The queen is the only female that produces offspring – fertilised eggs give rise to workers – unfertilised eggs give rise to males • When the colony reaches a certain size, the queen produces reproductive females, which leave the nest • Castes in eusocial insects are often highly specialised – among honey-pot ants (Camponotus), some individuals act as sedentary food stores for others in the colony Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and Saint Slides prepared by Karen Burke da Silva, Flinders University 30-37 Evolution of cooperation • Altruistic behaviour tends to reduce the reproductive success of an individual, so why does it persist in some species? – most ‘altruistic’ behaviour has a hidden benefit • Explanations of cooperation in eusocial behaviour – helping is of mutual benefit to parents and workers – workers are manipulated into helping parents – cooperation between individuals that are closely related evolves because they share a higher proportion of genes, so sisters may share more genes than mother and daughter Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and Saint Slides prepared by Karen Burke da Silva, Flinders University 30-38 Question 2: Which of the following is true? a) Natural selection does not favour altruistic behaviour that causes the death of the altruist b) Altruism is always reciprocal c) Natural selection is more likely to favour altruistic behaviour that benefits offspring than altruistic behaviour that benefits a sibling d) Natural selection should favour altruistic acts when the resulting benefit exceeds the cost to the altruist Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and Saint Slides prepared by Karen Burke da Silva, Flinders University 30-39 Summary • Behaviour has a genetic basis and therefore can be subject to the influence of natural selection • Behavioural choices generally reflect trade-offs between costs and benefits • Conflict over resources can result in contests between members of the same species • Courtship behaviour can be auditory, chemical or visual in nature and often allows for a female to choose a partner based on behaviour • Parental care increases the chances of offspring survival Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and Saint Slides prepared by Karen Burke da Silva, Flinders University 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