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Animal Behaviour and Plant Responses. Year 13 Biology Overview • Orientation – Tropisms – Nastic responses – Plant hormones – Taxes and Kineses – Migration and Dispersal – Homing Overview • Timing – Environmental Cycles – Biological clocks – Biological rhythms Revision • The environment – The environment includes all the factors, both living (biotic) and non-living (abiotic), that affect the lives of organisms. • Abiotic – The physical factors in an environment (non-living) • Biotic – The living factors in an environment. Revision • Main Abiotic factors – Light (photo-) – Gravity (geo- or gravi-) – Temperature (thermo-) – Water (hydro-) – Chemicals (chemo-) – Touch (thigmo-) – Current (rheo-) Revision • Abiotic Factors – are the physical parts of the environment to which organisms respond. For most organisms, the physical factors must be kept within quite a narrow optimum range that fits the tolerance for that species. – If the factor is extreme in either direction the organism suffers from physiological stress, and if the factor becomes too extreme it leads to death. (recall the zones of tolerance) Niche • Niche - You could say that the habitat is an organism’s address, and that the ecological niche is its profession. The ecological niche is a description of; – the opportunities provided by the habitat; and – The adaptations of the organism that enable it to take advantage of those opportunities. Adaptations • Most organisms are a combination of many adaptations that allow them to fit into their environment easily. Adaptations are grouped into three types; – Structural – Behavioural – Physiological Detecting a stimulus • A stimulus is a change in the environment (external or internal) that causes a response in an organism. • A receptor is any cell or group of cells that can detect this change • A effector is a cell or group of cells that can respond to the change. Detecting a stimulus Environmental stimulus Receptor detects Communicating system Coordinating system Effector responds Other information Orientation responses of plants • Plants respond to light, gravity, water, chemicals and touch. They do this by a growth curve towards or away from a stimulus. • If the growth is towards the stimulus we say it is positive; if it is away from the stimulus we say it is negative. • The prefixes you learnt before tell us the type of stimulus e.g. photo = light. Tropisms • A tropism is a GROWTH response towards or away from an environmental stimulus coming from one direction. • For example – If the shoot of a plant grows towards the light, we say it is positively phototropic – If the root of a seedling grows down, then we say it is positively geotropic Nastic Responses • The response of plants to diffuse stimuli that do not come from any particular direction, such as the temperature, humidity and light that surround a plant, are called nastic responses. • For example – the opening and closing of flowers in response to different light intensities. Nastic Responses • Nastic movements are classified according to the nature of the stimulus • For example – Photonasty is the response to alterations in the light intensity – Thermonasty is the response to changes in the temperature Plant structure Plant structure Plant structure Plant Hormones • Plants use hormones to regulate their growth and development. • Plant hormones (or phytohormones) are organic compounds produced in one part of the plant and transported to another part, where they produce a growth response. Plant Hormones • There are 5 groups of plant hormones; – Auxins (indolacetic acid or IAA) – Cytokinins – Gibberellins – Ethene – Abscisic acid (ABA) • Together they control growth and development on the plant at various stages. Auxin – indolacetic acid IAA • The effect of auxin on roots and shoots – The effect of auxin is different on the shoot, lateral buds (side buds found in the axis of the leaves where the leaf joins the stem), and the root. – It all depends on the concentration of the auxin The effect of auxin on plant growth Auxin Concentrations • Low auxin concentrations stimulate root growth, and high concentrations inhibit root growth. • Low auxin concentrations stimulate growth of lateral buds; high concentrations inhibit this. • Low auxin concentrations do not stimulate the growth of shoots, but high concentrations do. Apical dominance • Apical dominance – If you take a bean shoot and leave it to grow, the intact tip keeps the lateral buds from growing. – If, however you remove the apical bud (the bud at the tip of the main growing shoot) the two lateral buds start to grow within hours. – If you were to place a plug onto the apical bud that contained auxin you would find that the growth of the lateral buds is inhibited. Apical dominance Other effects of auxin • Cell elongation • Encourages root development • Involved in the abscission (dropping of leaves and fruit). It appears to delay this. • Stimulates growth of the cambium when a tree stem is under stress • Suppression of root elongation • Initiations of flowering in some plants Cytokinins • Produced mainly in the roots • Functions – Promote cell division – Slow down the process of aging (senescence) in plants. – If applied to leaves it can prevent the yellowing of mature leaves in autumn and their dropping (abscission) Gibberellins • Originates from a fungus Gibberella fugikuroi . This caused a disease that made plants grow so tall they toppled over and rotted. Gibberellins have now been isolated from this fungus. Gibberellins • Functions – Increases the internode length – Promotes the germination of a wide variety of seeds that would otherwise be hard to germinate – Causes flowering on biennials that normally need a period of chilling (vernalisation) Gibberellins • Which plant received gibberellin treatment? Ethene • The saying that ‘one rotten apple will spoil the barrel’ is actually true – a ripening apple gives off a gas called ethylene that ripens adjacent fruit, even a fruit of a different type! • Functions – Accumulates in mature fruit to induce ripening – Promotes leaf fall Abscisic Acid (ABA) • Generally abscisic acid functions as an inhibiting hormone acting against auxin, gibberellins and cytokinins all of which tend to promote growth • Functions – growth inhibitor made in the leaf chloroplasts in response to water stress. Acts on guard cells causing stomatal closure – Induces leaf fall (only in a few selected species) – Promotes seed dormancy Biological orientation responses in animals • In this case the term orientations means a behaviour by which the animals positions itself in a certain way in relation to its surroundings. • These include taxes and kinesis, homing and migration. Taxis • This is the movement of the whole animal, towards or away from a stimulus which is coming from one side only. • As with tropisms, movement towards a stimulus is positive and away from a stimulus is negative. • The stimulus is also denoted by the same prefixes. Taxis • Examples – Flatworms moving towards a pieces of raw meat are showing positive chemotaxis – Moths flying to a light are positively phototactic – Trout will line themselves up in an upstream direction, so they are positively rheotactic Taxis • Taxes often involve moving the head (which carries the sensory receptors) from side to side. • If there are two sensory organs then the animal can move directly towards or away from the stimulus as it can constantly check the position of the stimulus. • If there is only one sensory organ, the animal must move around to get information about the stimulus. E.g. a maggot must move its head from side to side to keep in position. It performs a zigzag ‘direct’ line. Taxis • Task – Identify the environmental cue involved and the adaptive value of the behaviour 1. Chemotaxis 2. Thermotaxis 3. Phototaxis 4. Thigmotaxis 5. Gravitaxis 6. Hydrotaxis Kinesis • This is a non-directional response to a stimulus. • It is the change in activity rate in response to a change in the intensity of the stimulus. • Example – If woodlice are placed in a wet/dry choice chamber, the animals in the dry side increases their random movements and rate of turning compared with those on the wet side. Kinesis • Orthokinesis – the speed of the movement is related to the intensity of the stimulation • Klinokinesis – the amount of random turning is related to the intensity of the stimulation. • See diagrams for summary. Pheromones • A pheromone is a chemical produced by an animal and released into the external environment where it has an effect on the physiology or behaviour of members of the same species. • Task – Outline the many ways animals use pheromones. Migration • Refers to regular, annual or seasonal mass movements made by animals from their breeding area to another area. Advantages of Migration • • • • • • • • Animals remain in a favourable temperature They grow larger They leave more offspring They have a constant supply of food It may lead to the colonisation of a new area Reduces predation/parasitism disease Greater genetic mixing Better breeding conditions Disadvantages of Migration • They may get lost or caught in a storm • They may get eaten by a predator • The may use up too much energy in the migration, leading to exhaustion • They may starve • It is a huge investment in energy Trigger to migration • The behavioural trigger that sets off migratory behaviour varies. • Some trigger include – Maturation – some animals migrate as the sex organs mature and there is a need or desire to reproduce – Environmental cues – such as drop in temperature, shortening of the length of the day e.g. migratory birds (migratory restlessness) – Genetic Drive – The trigger may be inbuilt (innate) e.g star patterns for navigation are learned, but how to learn then is innate – Endogenous circadian rhythm – internal biological clock. Methods of Migration • Piloting – An animal moves from one landmark that it is familiar with to another landmark, until it reaches its destination – Generally used over short distances and uses visual cues. Methods of Migration • Compass Orientation – an animal can detect a compass direction, and travels in a straight-line path until it reaches its destination. This can be accomplished using the magnetic field lines of the earth, chemical cues and sound. Methods of Migration • Navigation – is the process by which an animal uses various cues to determine its position in reference to a particular goal. Methods of Navigation • • • • • • Visual Solar Magnetic fields Stellar (stars) Chemical Sonar (sound) Homing • This is the ability of an individual to return to the home site after it has been away to look for food, sometimes over considerable distances. Timing Responses • Timing – Environmental Cycles – Biological clocks – Biological rhythms Environmental Cycles • The astronomical cycles – The motions of the Earth, moon and sun result in complex and interdependent cycles. – These create environmental changes that range from short term to long term. Biological Rhythms • Environmental cues such as daylength, timing and the height of tides, and phase of the moon are often used by plants and animals to establish and maintain a pattern of activity. • They synchronize important events in the life cycle of an organism. Biological Rhythms • Biological rhythms in direct response to environmental stimuli are said to be exogenous – the rhythm is controlled by an environmental stimulus that is external to the organism • Those rhythms that continue in the absence of external cues are said to be endogenous The Biological Clock • Biological clock – an internal timing system which continues without external time clues, and controls the timing of activities of plants and animals. • Uses of biological clocks – Control of the daily rhythms of the body e.g. sleep, pulse, metabolic rate, sex drive – Reproductive timing – Preparing for migration by eating a lot of food – Preparing for winter by storing a lot of food – Navigating by the sun or the stars. Some Biological Rhythms • Circadian – daily activity period, approximately 24 hours (circa=about, dies=day) • Circatidal – tidal activity period, approximately 12.4 hours • Circasemilunar – spring/neap tidal period, approximately 14.7 days (semilunar=half moon) • Circalunar – monthly activity period, 29 days (circa=about, lunar=moon) • Circannual – yearly activity period, approximately 360 days (circa=about, annual=year) Daily Cycles in Animals (circadian rhythms) • Animals are active at different times of the day: – Diurnal – active during the day, inactive at night – Nocturnal – active at night, inactive during the day – Crepuscular – active at dawn and dusk – Arrhythmic – no regular pattern Other Important Terms • Free running period – when the biological clock is running without any clues for the environment, so is ‘running free’ • Entrainment – the resetting of the biological clock on a regular basis, forcing it to take up the period of the environment. This is done with a Zeitgeber. • Zeitgeber – (‘time giver’ – the German word is the most commonly used) – the environmental agent that resets the biological clock. This could be light, temperature etc. Plant Rhythms • Plants are capable of responding to environmental variables in a variety of ways. • Some activities follow daily rhythms, while others are seasonal. Photoperiodism in Plants • Photoperiodism is the response to the relative length of daylight and darkness. • Photoperiodic activities are controlled by a pigment called phytochrome. It acts as a signal for some biological clocks in plants and is also involved in other light initiated responses such as germination, shoot growth and chlorophyll synthesis. The flowering of Plants • A photoperiodic response of plants depends on the critical night length • Plants can be divided into 3 types: – Short-day plants – Long-day plants – Day-neutral plants The flowering of plants • Short-day plants – Require a short day and long night – Will flower if the photoperiod is less than a certain critical length • Long-day plants – Require a long day and short night – Will flower if the photoperiod is greater than a certain critical length The flowering of plants • Day-neutral plants – Flowering is unaffected by the amount of daylight per day. – See page 197 biozone The Phytochrome System • Photoperiod of plants controlled by pigment phytochrome • There are two forms of this pigment – P665 (Pr) – inactive form that absorbs red light – P725 (Pfr) – active form that absorbs far-red light The Phytochrome System • So how does it all work? – During the day P665 absorbs red light (present during the day) and as a result is quickly converted to the active form, P725. – This P725 then accumulates. – During the night P725 absorbs far-red light (present during the night) and slowly converts back to the inactive form, P665. The Phytochrome System • What is the link between this system and flowering? – If the day is long enough P725 accumulates and long-day plants flower – If the night is long enough P665 accumulates and short-day plants flower (it is thought that this may be due to the low concentration of P725 rather than high concentrations of P665) Plant Responses to the Biotic Environment • • • • • Plant-plant relationships Plant-fungi relationships Plant-animal relationships Plant defences (aggressive) Co-operative relationships Plant-plant relationships • Relationships between plants is more complex than you might think. • Examples – Allelopathy – this is when a plant may secrete a toxic substance from their roots or leaves that inhibits plants growing near them. • E.g. Chaparral bush, black walnut – Seed dispersal mechanisms – ensures spread of offspring over a wide area Plant-plant relationships – Growing larger leaves to capture available light when it is reduced – Plants arranging in layers (stratification) in response to differing environmental conditions (will have adaptations enabling them to survive in certain layers) – Epiphytes – grow on other trees to gain access to better conditions – Lianas – plant climb up trees – These are just some examples – Plant-fungi relationships • Many plants will form relationships with Fungi – Mycorrhizal fungi form mutualistic relations with many plant roots. The fungi help the plant roots absorb water and minerals and in return get organic molecules (nutrients) made by the plant by photosynthesis – Obligate mutualistic relationships – lichen (made up of algae and fungi) that are obliged to live together. Fungi absorbs water and nutrients and keeps the algae wet and the algae carries out photosynthesis and provides sugars and food for the fungus. Plant-animal relationships • Herbivores eat plants by – Grazing – Browsing – Suck sap – Feed on nectar, pollen, fruit and seeds – Chew roots – Eat gum Plant defences • Plants must have strategies to defend themselves against herbivory. – Examples • • • • • • Thorns Divarication Chemicals Low growing point Seed masting Hiding etc Co-operation in plants • Co-operative interactions between plants and other plants, and plant and animals can include – Pollination – animal pollinators (insects/birds) are attracted by rewards or advertisements – Guarding plants by animals – Animals gaining protection from thorns – Eating fruits and seeds pass through digestive track and are dispersed Overview • Species Interactions – Behaviour and communication – Social Organisation – Courtship and pair bonding – Aggressive behaviour – Interspecific interactions – Intraspecific interactions Animal Responses to the Biotic Environment • Intraspecific responses – aggressive and co-operative • Interspecific responses – aggressive and co-operative • Complete pages 208 Biozone Intraspecific aggressive responses • Agonistic behaviour – Is aggressive – Towards members of the same species – Involves threats or fighting – Determines which competitor gains access to resources. – Especially strong between members of the same sex e.g. males fighting over females. • Biozone pg 213 Intraspecific aggressive responses • Territories – Are established areas for feeding, mating or rearing young, that are defended. – Held by aggressive behaviours – Usually consist of a lair or nest in the centre of the territory, surrounded by a large home range that animals cover regularly in search of food and mates. – Only the territory is defended Intraspecific aggressive responses • Advantages of territoriality – Ensures space for each animal – Reduces disease – Harder for predators to find animals if they are spread out – Reduces fighting – Ensures there is enough food for everyone – Safe breeding sights that are defended – Best genes are handed on to offspring Intraspecific aggressive responses • Disadvantages of territoriality – Males without territories fail to breed as not seen as attractive – Losers must spread out to find food rather than fight – Biozone 217-219 Intraspecific aggressive responses • Marking and defending – Singing – Mark with urine – Using scent glands – Using signals – Calling Intraspecific aggressive responses • Hierarchies – when every animal is either above or below another (linear hierarchy). – There are no equals – Forms “Pecking Orders” (see pg 221-222) – Usually established competitively – “top dog” will usually make decisions for the group – Maintained by posture and display Intraspecific co-operative behaviour • Includes – Group formation – Courtship and pair-bond formation – Parental care Group Formation • When animals join together to cooperatively undertake tasks – E.g. Hunting, defence, protection etc Advantages of forming groups • Team work while hunting leads to increased success rate. • Less predation as can have members of the group on “look out” • Older members protect young or weak individuals • Large numbers can cause confusion for predators • Breeding sites are located within a boundary that is protected by members of a group Disadvantages of group formation • • • • Competition is increased Disease can spread faster Parasites (e.g. fleas) spread faster Increases conflict between members Courtship/pair-bond formation • Requires co-operation, suppression of aggressive behaviours and communication. • Usually females make the choice who they mate with, but both partners need to make sure; – They are the same species – Both fertile – Both fully prepared to mate. – See 225 Courtship • Males usually will compete for the attention of females by; – Competing with other males by fighting or ritualised combat – Compete indirectly by attracting females by displays and adornments • E.g. antlers in deer, brightly coloured feathers in peacocks, singing and dancing of many bird species, producing pheromones. Pair-bond relationship • A stable relationship between animals of the opposite sex that ensures co-operative behaviour on mating and rearing of the young – E.g. turns, albatross Parental Care • Survival depends on successfully breeding adequate numbers of offspring. • Can be achieved by to possible strategies – R-strategy – produce large numbers of unprepared offspring with a low chance of survival – K-strategy – produce few, well prepared offspring which have a high chance of survival – See 227 Biozone. Parental Care • Degree of parental care depends on the species – E.g. eggs buried and then abandoned (many fish species), nest constructed and defended, offspring themselves defended – Often those species that have a high degree of parental care will teach their offspring how to find food, where to find water, how to make a home etc. Reproductive Strategies • Monogamy – each mating with only one member of the opposite sex (often for life) • Polygyny – males mate with many females thus fathering many offspring • Polygamy – dominant males mates with a harem of females • Polyandry – females mate with more than one male • Polygynadry (promiscuity) – both male and female mate with more than one member of the opposite sex. • See 224 Biozone