FURTHER STUDIES OF BEHAVIOUR AHL Option E.6 IB Biology Miss Werba

OPTION E - NEUROBIOLOGY STIMULUS and RESPONSE E.2 PERCEPTION of STIMULI E.3 INNATE and LEARNED BEHAVIOUR E.4 NTs and SYNAPSES E.5 THE HUMAN BRAIN E.6 FURTHER STUDIES IN BEHAVIOUR J WERBA – IB BIOLOGY 2

THINGS TO COVER Social behaviour Natural selection & social behaviour Altruistic behaviour Foraging behaviour Mate selection Rhythmical behaviour J WERBA – IB BIOLOGY 3

SOCIAL BEHAVIOUR Command term = DESCRIBE Social behaviour: behaviour directed towards, or taking place between, members of the same species Examples: Honey bees Mole rats J WERBA – IB BIOLOGY 4

SOCIAL BEHAVIOUR Command term = DESCRIBE Honey bees Honey bees live in colonies of 20,000+ individuals Individuals in the colony interact closely and have set functions and responsibilities. These are referred to as castes. Most individuals in the colony are workers and there is one queen. There are also drones, whose only function is to mate with the queen. J WERBA – IB BIOLOGY 5

SOCIAL BEHAVIOUR Command term = DESCRIBE Honey bees Queen: There is only one queen in each colony! Function = to produce eggs Only leaves the hive to mate and swarm Controls colony activities through pheromones (scent) Mates with many males at one time and stores sperm to be used throughout her life Lays thousands of fertilised eggs in the cells of the honey comb J WERBA – IB BIOLOGY 6

SOCIAL BEHAVIOUR Command term = DESCRIBE Honey bees Workers: All female Non-reproductive Perform a series of roles in order as they mature: young bee, nurse, builder, guard, honeymaker Live for ~30 days Feed the queen and drones J WERBA – IB BIOLOGY 7

SOCIAL BEHAVIOUR Command term = DESCRIBE Honey bees Drones: All males Haploid (ie. only have one set of chromosomes) Their only function is to mate Mate with the queen in the air and die soon after J WERBA – IB BIOLOGY 8

SOCIAL BEHAVIOUR Command term = DESCRIBE Honey bees When the colony gets too big, the queen will prepare to leave If this is the case, some of the larvae are fed a high protein diet  they will develop into queens. Otherwise, they will develop into workers. The old queen will leave with half the colony and the new queen will emerge. The drones will follow the new queen. She will be fertilised and store the sperm to be used over the next few years. J WERBA – IB BIOLOGY 9

E.6.1 regulates activity Drones secrete pheromones fertilise queen clean hive Honey bee colony Worker bees Queen bee Young 3-5days fed special diet guard hive Adult 21-40days forage Maturing 5-20days build hive leave hive process honey control Tº feed larvae Lays fertilised eggs fed normal diet

SOCIAL BEHAVIOUR Command term = DESCRIBE Naked mole rats Mole rats live in underground colonies of up to 80 individuals They are blind. Individuals in these colonies also set functions and responsibilities. There is one queen and a small number of reproductive males. The queen is the only female who is allowed to mate. J WERBA – IB BIOLOGY 11

SOCIAL BEHAVIOUR Command term = DESCRIBE Naked mole rats Non-reproductive females act altruistically to promote survival of the queen and her offspring. When the queen dies however, competition between females becomes fierce as the other females compete to take her place The sterility of the workers is not genetic but maintained by the queen using pheromones. The burrow itself could not be constructed or defended without social organisation. Either the colony as a whole survives to form new colonies or it doesn’t. J WERBA – IB BIOLOGY 12

NATURAL SELECTION IN A COLONY Command term = OUTLINE A colony of individuals with set roles displays emergent properties. Which means....??? That the whole colony is more than the sum of its parts. All individuals are closely related genetically. Advantageous traits in a caste that promote the reproductive fitness of the queen will be selected for. These genes will be propagated through the species. J WERBA – IB BIOLOGY 13

ALTRUISTIC BEHAVIOUR Command term = OUTLINE Altruistic behaviour: behaviour that benefits others and involves risk or cost to the performer. Altruistic behaviour is the product of natural selection. Innate behaviours are genetic and therefore subject to natural selection. Examples: parenting care by mammals Ants Vampire bats J WERBA – IB BIOLOGY 14

ALTRUISTIC BEHAVIOUR Command term = OUTLINE Ants Demonstrate altruism through kin selection, in a similar way to honey bees They ensure that closely related individuals are promoted, thus ensuring the survival of shared genes Males are haploid, females are diploid Therefore all females are 75% genetically similar By acting altruistically to defend the colony, raise the young or feed the queen, individual workers promote their own genes. J WERBA – IB BIOLOGY 15

ALTRUISTIC BEHAVIOUR Command term = OUTLINE Vampire bats Demonstrate reciprocal altruism They ensure their own survival and reproductive success by helping another individual. They need to feed on blood every 24-36hrs or they lose body weight quickly and can die. They have a blood-sharing system, where unrelated bats share blood with each other. Individuals who do not reciprocate are expelled from the sharing group and are therefore unlikely to survive should they need blood later. J WERBA – IB BIOLOGY 16

FORAGING BEHAVIOUR Command term = OUTLINE Foraging behaviour: behaviour that allows for the collection of food that is available in nature, by gathering, fishing or hunting. The benefit must exceed the cost. As long as the benefit of energy outweighs the energy and time expended, the foraging strategy being used will benefit the individual’s reproductive fitness. Examples: Bluegill sunfish Crown of thorns starfish J WERBA – IB BIOLOGY 17

FORAGING BEHAVIOUR Command term = OUTLINE Bluegill sunfish These fish live in ponds where they prey on small invertebrates, including Daphnia. When food is scarce, the fish will consume all sizes of Daphnia. When food is abundant, bluegills are more selective with their prey, choosing only larger Daphnia. Consuming small numbers of large prey takes less energy than large numbers of small prey, so it represents a better benefit:cost ratio. J WERBA – IB BIOLOGY 18

FORAGING BEHAVIOUR Command term = OUTLINE Crown of thorns starfish These starfish live graze on coral polyps, the organisms that build coral reefs. They will remain in an area for as long as it is beneficial to forage there, and then they move on. This gives them a high benefit:cost ratio. They are causing widespread damage to coral reef systems, each individual starfish clearing 6m2 of reef per year. J WERBA – IB BIOLOGY 19

COURTSHIP BEHAVIOUR Command term = EXPLAIN Sexual selection or courtship behaviour: behaviour that results in mating and eventual reproduction, involving chemical, visual, or auditory stimuli. Females often choose their mate So males need to attract females in order to mate Males may also need to fight other males to establish dominance Example: Peacocks J WERBA – IB BIOLOGY 20

COURTSHIP BEHAVIOUR Command term = EXPLAIN Peacocks The peacock tail is an exaggerated trait to attract females of the species. They advertise reproductive fitness, but deliver it at a survival cost. Mate selection can drive speciation between separated populations. J WERBA – IB BIOLOGY 21

RHYTHMICAL BEHAVIOUR Command term = STATE Animals show rhythmical variations in activity. These behaviours are innate, so they are subject to natural selection. Rhythmical behaviour: behaviour and activities that change rhythmically (over regular time periods – eg. seasons, days, months). Example: Seasonal migration patterns of whales Turtle nesting according to lunar cycles Bee populations booming during spring J WERBA – IB BIOLOGY 22

Peacock spiders

Sample questions Q1 (5 min) Discuss the evolution of altruistic behaviour in a non- human species. [6] J WERBA – IB BIOLOGY 24

Sample questions Q2 (8 min) J WERBA – IB BIOLOGY 25

Sample questions Q2 State the effect of the presence of the helpers on i. mean chick mass. [1] ii. the probability of survival of the breeding females until the next breeding season. [1] Calculate the percentage decrease in mean egg volume found in the presence of helpers as compared to the parents only. Show your working. [2] With reference to the data, suggest why the activity of the helper affects the probability of survival of the breeding female until the next breeding season. [2] J WERBA – IB BIOLOGY 26

Sample questions A1 altruistic behaviour may be harmful to the animal itself but beneficial to other animals; occurs in social animals; usually occur in the same species; need not happen between genetically related animals from one population; altruistic behaviour often occurs in animals which are genetically closely related; altruistic behaviour may increase the survival rate of the group and thus the species; helping close relatives or siblings increases the chances of passing on genes to the next generation; due to natural selection; this is called inclusive fitness; enhancing reproductive success of relatives is called kin selection; if altruism was a negative trait it would / may have disappeared; altruistic species do just as well as non-altruistic species belonging to the same order; 6 max J WERBA – IB BIOLOGY 27

Sample questions A2 i. (mean) chick mass increases in presence of helpers. [1] ii. female survival probability increases in presence of helpers [1] (1300-1225)/1300 * 100% = 5.8% (Accept the correct answer if it is not rounded up to 5.8% or if it is rounded up to 6%) [2] with helper, smaller egg volume; less resources from mother to produce egg/rear young; more resources toward survival of mother [2] J WERBA – IB BIOLOGY 28