GENETICS & ADAPTATION

GENETICS & ADAPTATION Obtaining Food in Animals Mr G Davidson

Foraging Behaviour and Search Patterns • All animals have a common problem: they use food as an energy source but finding that food uses up lots of energy. • It is therefore important that every animal forages ( searches) for food in an efficient manner. Mr G Davidson

Foraging Behaviour and Search Patterns • An animal must have an optimum foraging strategy which will maximise energy gain and minimise energy loss. • If the animal consistently fails to make an energy profit (gains more energy than it uses), it dies of starvation. Mr G Davidson

Competition • Competition occurs between species and individuals when any resource is in short supply: • Resources can be food, space, mates, shelter, water etc. • Generally competition results in drastic decline of numbers in the failing species or individuals Mr G Davidson

Competition • In animals, interspecific competition arises when two organisms of different species occupy the same ecological niche. • An organism’s niche is its role in a food web. • This is determined mostly by its feeding habits. Mr G Davidson

Competition • The successful competitor will be able to: • Obtain food more effectively than the competing species. • exploit the areas of its niche not in common with its competitor’s niche, e.g. when a competitor is present it may select different prey from normal. Mr G Davidson

Competition • Intraspecific competition arises when overcrowding occurs within a population of the same species. • There is insufficient food for an energy profit for all individuals • This will result in behavioural responses such as migration and aggression. Mr G Davidson

Territorial Behaviour • Territorial behaviour is shown by an animals or group of animals in their defence of a definite area. • The size of area defended, called the territory, will depend upon a number of factors. Mr G Davidson

Territorial Behaviour • One of the most important being food availability. • Territorial behaviour can be considered in terms of costs and benefits. Mr G Davidson

Territorial Behaviour • The major factors are:- • If the territory is too small, not enough food is obtained • If the territory is too big, it costs too much energy to defend it • As food quality goes up, the size of territory goes down • Territories which are settled result in reduced aggression with consequent energy saving e.g. robin red breast defends a small garden which provides enough food for its own needs and for its mate and young when breeding by displaying its red breast and singing. Mr G Davidson

Territorial Behaviour • For Example Planarian worms live on the mud at the bottom of streams and lakes. Only when their territories overlap will aggressive cannibalism take place. Mr G Davidson

The Social Group • In the wild, it is an advantage for some animals to live in groups. • There are many obvious advantages – many eyes, many hands and many bodies that make tasks such as catching prey, easier to accomplish. • A lone wild dog could not hope to catch a large deer on its own. Mr G Davidson

The Social Group • But living together creates more competition. • This is seen when feeding birds; squabbles arise but fighting is rare. • This is because certain strategies are employed to reduce conflict. Mr G Davidson

Dominance Hierarchy Mr G Davidson

Co-operative Hunting Mr G Davidson

Avoidance and Habituation • The simple earthworm will need to suddenly withdraw into its burrow to avoid being eaten by peckish birds. • But what if it is touched by a moving branch each time it emerges? Mr G Davidson

Avoidance and Habituation • It possesses a behavioural adaptation called habituation that allows it to cease responding to repetitive non-harmful stimuli. • Avoidance behaviour and habituation have such important survival value that they are found in every animal. Mr G Davidson

Associative Learning • Habituation is a short term and often short-lived response. • Longer term learning is needed for an animal to accumulate the experiences which enable it to function more efficiently. Mr G Davidson

Associative Learning • If an animal can remember what stimuli make finding food easier then it will be able to survive and conserve energy better. • Most animals can make these associations between stimuli and behaviour. • This is called conditioning or associative learning. Mr G Davidson

Associative Learning • There are essentially two types of conditioning: • classical (instrumental) conditioning • when an animal associates different stimuli from the environment with each other, e.g. a dog getting excited and salivated when a can opener is used. • operant conditioning (Trial and error) • when an animal learns to associate its behaviour with the results of that behaviour. • e.g. Chimps using sticks to extract termites from nests. Mr G Davidson

Associative Learning • Associative learning is dependent on repetition and reinforcement which involves either reward of punishment. • Much of our own behaviour is learned in this way, particularly during early years of exploration. Mr G Davidson

GENETICS & ADAPTATION